Publications

• Vu, Trong Dai; Le, Minh Hoang & Dinh, van Khuong (2026). Extreme warming increases metabolic demand and diminishes acidification effects on larval survival in the dog conch Strombus canarium. Frontiers in Marine Science. 13, p. 1–11. doi: 10.3389/fmars.2026.1914485. Full text in Research Archive
• Kline, Simon Hasselø; Hyvärinen, Olli Petteri; Valestrand, Louise; Andersen, Tom; Eikrem, Wenche & Titelman, Josefin [Show all 8 contributors for this article] (2026). 15-year shift in protist communities and a decline of heterotrophic dinoflagellates in the Oslofjord and Skagerrak. Frontiers in Marine Science. 13. doi: 10.3389/fmars.2026.1876109. Full text in Research Archive
• Sanchez, Pedro Maria Martin; Wurzbacher, Christian; Fontaine, Laurent; Lara, Maria Jimenez; Juottonen, Heli & Valiente, Nicolas [Show all 9 contributors for this article] (2026). Low determinism in community assembly of transient and resident pelagic fungi across climate zones in Scandinavian lakes. mSystems. 11(9). doi: 10.1128/msystems.00691-26. Full text in Research Archive Show summary

  ABSTRACT In lakes, fungi play pivotal roles in biogeochemical processes, particularly in the decomposition of organic matter. However, these organisms have been underrepresented and taxonomically unresolved in previous research. In this study, we employ high-resolution sequencing to delve into the fungal diversity within two distinct Scandinavian Lake data sets spanning a vast latitudinal gradient across Norway and Sweden, diverse climatic zones ranging from nemoral to arctic, and a wide spectrum of nutrient conditions. Utilizing eukaryotic 18S primers, we reveal that fungi contribute, on average, 2.07% in the Norwegian and 5.4% in the Swedish sequencing data set, with remarkable spikes of up to 55% in forested lakes. Fungus-specific 5.8S-ITS2 sequencing identified the prevalence of several fungal phyla, including Ascomycota , Rozellomycota , Basidiomycota , Chytridiomycota , Aphelidiomycota , and Mortierellomycota . Notably, our research uncovers a striking degree of variability in fungal communities across the studied lakes. Null model analyses on the entire community, as well as subsets of transient and resident members, revealed that deterministic selection plays a secondary role. Instead, community assembly was overwhelmingly governed by stochastic ecological drift across all tested groups. These findings challenge conventional paradigms of eukaryotic communities being strongly guided by deterministic processes and underscore the complexity of community assembly processes across the fungal kingdom. The dominance of ecological drift and stochasticity in the assembly process emphasizes that conservation should target entire communities, processes, and areas instead of single species, as should be the case in deterministically assembled communities. IMPORTANCE Fungi perform a range of key functions in freshwater environments. Here, we show that fungi, including members of the phyla Ascomycota , Rozellomycota , Basidiomycota , and Chytridiomycota , represent a diverse part of the epilimnetic planktonic community in Scandinavian lakes. Fungal community assembly across northern climate zones is shown to have a low signal for determinism, as environmental sorting was weak in overwriting dispersal-related processes and ecological drift. Furthermore, we expand knowledge of the ecological range of key freshwater fungi and link taxa to biogeographic patterns in lakes.

• Vu, Ngoc Anh; Le, Minh Hoang; Lu, Tuan Anh Hoang; Luu, Hoang Viet; Doan, Nam X. & Truong, Kiem N. [Show all 7 contributors for this article] (2026). Timing of marine heatwave exposure across developmental stages modulates the copper effects on fitness traits in tropical copepods. Frontiers in Marine Science. 13, p. 1–12. doi: 10.3389/fmars.2026.1843680. Full text in Research Archive
• Hich, Tran Vi; Dinh, van Khuong; Cuc, Nguyen Thi Kim; Giang, Nguyen Thi Thuy; Phuong, Pham Thi Dan & Minh, Nguyen Cong [Show all 7 contributors for this article] (2026). Chitosan nanoparticles derived from molted shrimp shells as biodegradable adjuvants for Vibrio harveyi vaccination in Asian sea bass (Lates calcarifer). Regional Studies in Marine Science. 102. doi: 10.1016/j.rsma.2026.105385. Full text in Research Archive
• Jourdain, Eve Marie; McKinney, Melissa A.; Remili, Anaïs; Andvik, Clare Margaret; Fagerlund, Carl Johan Ludwig & Karoliussen, Richard [Show all 8 contributors for this article] (2026). Advancing Amino Acid Isotope‐Inferred Trophic Ecology in an Apex Predator: Insights From a Data‐Rich Killer Whale Population. Ecology and Evolution. 16(8), p. 1–16. doi: 10.1002/ece3.74121. Full text in Research Archive Show summary

  Amino acid‐specific nitrogen isotope analysis (δ 15 N‐AA) is increasingly used to infer trophic ecology, yet remains poorly validated in marine predators. We analyzed bulk tissue δ 15 N ( 15 N/ 14 N) and δ 13 C ( 13 C/ 12 C), and δ 15 N‐AA in 105 skin samples collected from individually identified Norwegian killer whales between 2017 and 2023. Forty‐two individuals with best documented diets in 2010–2023, based on field observations and corroborated by mercury concentrations and bulk tissue δ 15 N values in skin, provided reference diet groups against which δ 15 N‐AA‐derived hypotheses were tested: Fish‐only (100% fish prey; n  = 15), Intermediate mixed diet (~10% mammalian prey in addition to fish; n  = 14), and Top mixed diet (~50% mammals, 50% fish prey; n  = 13). Univariate and multivariate approaches identified diet as the primary driver of δ 15 N variation across individual amino acids and multivariate isotopic space, whereas sex and life stage had little effect. However, substantial inter‐individual variation remained unexplained and appeared to reflect metabolic processes. Metrics δ 15 N ΣTrophic—ΣSource (δ 15 N difference between the sum of trophic amino acids and the sum of source amino acids) and isotopic difference between glutamic acid/glutamine (Glu) and phenylalanine (Phe) (δ 15 N Glu–Phe ) successfully identified Top mixed diet whales but lacked the sensitivity to identify Intermediate mixed diet individuals, whilst δ 15 N values of Threonine showed no relationship with trophic position. Proline (Pro) and Phe used as trophic‐source pair provided the first plausible δ 15 N‐AA‐derived trophic position estimates for killer whales and performed better than bulk isotope‐derived trophic position when a priori knowledge was not available. Multivariate clustering of δ 15 N‐AA data complemented trophic position estimates by resolving finer‐scale dietary variation occurring within trophic levels.

• Nowicki, Robynne; Gabrielsen, Geir W.; Borgå, Katrine; Søreide, Janne & Varpe, Øystein (2026). Seasonality and water masses shape energetics of a high Arctic fish: quantifying energy density and condition indices. Marine Ecology Progress Series. ISSN 0171-8630. 786. doi: 10.3354/meps15150. Full text in Research Archive Show summary

  Seasonal life history decisions and environmental factors shape energetics over annual cycles. We quantified seasonal energy density of polar cod Boreogadus saida , a central predator and prey in the Arctic marine food web. We collected individuals from Atlantic and polar waters in the Barents Sea, to assess the impact of seasonality and water masses on energy density (kJ g -1 wet weight (WW)). Additionally, we compared energy density to 4 condition indices (Fulton’s, residual and hepatosomatic indices, and percent dry weight) to test their accuracy as energetic proxies for polar cod. Energy density varied seasonally and was lower in Atlantic waters. In polar waters, energy density was lowest in April/May, whereas seasonal variation was weaker in Atlantic waters. Energy density was highest in December in both water masses, although not much higher than March in polar water. Differences between water masses were seasonal, greatest in March (Atlantic: 4.07 ± 0.53 kJ g -1 WW; polar: 5.77 ± 0.62 kJ g -1 WW) and negligible in December (5.66 ± 0.83 and 5.86 ± 0.62 kJ g -1 WW, respectively). Percent dry weight best represented energy density, while Fulton’s and residual (derived from WW) indices were poorly correlated to energy density. Our results show that seasonality and environmental factors shape energetics, and that energy proxies must be carefully selected to accurately represent the energetic status of an organism. Our seasonal resolution highlights potential ‘critical windows’, when polar cod may be most vulnerable to stressors, whilst our spatial comparison provides insight into potential impacts of ongoing Atlantification.

• Sim, Clarence Wei Hung; Walde, Marie; Strindberg, Hanna; Kaur, Avneet; Panse, Sophie Le & Gourvil, Priscillia [Show all 9 contributors for this article] (2026). Labyrinthula merlionensis sp. nov.: A Novel Labyrinthulid Infecting Marine Diatoms. Journal of Eukaryotic Microbiology. ISSN 1066-5234. 73(5). doi: 10.1111/jeu.70111. Full text in Research Archive
• Andvik, Clare Margaret; Fagerlund, Carl Johan Ludwig; Jourdain, Eve Marie; Yuan, Bo; Haddad-Weiser, Gabrielle & Lyche, Jan Ludvig [Show all 9 contributors for this article] (2026). Comparing polychlorinated n-alkane occurrence and biomagnification with legacy contaminants in a killer whale food web. Environmental Research. ISSN 0013-9351. 306. doi: 10.1016/j.envres.2026.125367. Full text in Research Archive Show summary

  Polychlorinated n-alkanes (PCAs), the largest component of the commercial product chlorinated paraffins, have been used globally in increasing amounts since the regulations of legacy contaminants, such as polychlorinated biphenyls (PCBs). The bioaccumulative potential of PCAs compared to legacy contaminants is inconclusive, with limited data available for PCAs with carbon chain length ≤9 and ≥18, particularly in food webs which include mammalian top predators. Here, we analysed and compared PCAs of different carbon chain length (very-short: PCAs-C6-9 [vSCCPs], short: PCAs-C10-13 [SCCPs], medium: PCAs-C14-17 [MCCPs], and long: PCAs-C18-24 [LCCPs]), 57 legacy contaminants, and total mercury (Hg) in killer whales (Orcinus orca) from northern Norway (n = 59) and a range of fish and marine mammals. We found that legacy organic contaminants dominated in concentration and pattern in marine mammals (54–87%), whereas PCAs and Hg dominated in fishes (58–98%). A species' physiology (poikilotherm or homeotherm) influenced the food web magnification of several contaminants, with estimated trophic magnification factors (TMFs) underestimated in PCAs, and overestimated in PCB-153, p.p’-DDE and Hg, if unaccounted for. PCAs-C6-9 and PCAs-C10-13 had similar and low TMFs for poikilotherms and homeotherms, and similar to PCB-28 (TMF range: 1.9–2.4 [95% confidence interval 0.9–5.7]). PCAs-C14-17 and PCAs-C18-24, had high TMFs in poikilotherms (4.8 [1.3–18] and 4.6 [1.2–18], respectively), and no significant trophic magnification in homeotherms (1.0 [0.5–2.3] and 1.0 [0.4–2.8], respectively), with the opposite pattern for PCB-153 and p.p’-DDE. Our results indicate higher PCA concentrations and biomagnification potential in poikilotherms than homeotherms, which is likely due to lower biotransformation and elimination ability.

• Konestabo, Heidi Sjursen; Leinaas, Hans Petter; Gestel, Cornelis A.M. van & Borgå, Katrine (2026). Prior pesticide exposure reduces drought tolerance in Arctic and temperate springtails—Effects of sequential stressors. Environmental Toxicology and Chemistry. ISSN 0730-7268. 45(6), p. 1460–1469. doi: 10.1093/etojnl/vgag046. Full text in Research Archive
• Tepanosyan, Gevorg; Gevorgyan, Astghik; Poghosyan, Zhenya; Sahakyan, Lilit & Puts, Isolde Callisto (2026). Arsenic and Phosphorus contamination in sediments along the urban river continuum in Yerevan (Armenia). Soil & sediment contamination. ISSN 1532-0383. doi: 10.1080/15320383.2026.2678982. Full text in Research Archive
• Hofmann, Laurie Carol; Bartsch, Inka; Pehlke, Hendrik; Alves-Lima, Cicero; Barreto, Luís M. & Bermejo, Ricardo [Show all 27 contributors for this article] (2026). Assessment of the macroalgal genetic resources maintained in European germplasm banks. Journal of Applied Phycology. ISSN 0921-8971. doi: 10.1007/s10811-026-03882-0. Full text in Research Archive Show summary

  Germplasm banks are important for preserving genetic diversity, yet the availability and long-term maintenance of macroalgal strains in germplasm banks is currently limited in European collections. To support future food security, restoration efforts, and biotechnological innovation, a strategy was recently developed for the long-term preservation of macroalgal genetic diversity. A foundational step in this effort is to assess the existing biodiversity, biogeographical distribution, and commercial relevance of seaweed cultures maintained in European collections. Using a universal data-collection template distributed widely across European seaweed networks, we compiled and analysed information on these seaweed cultures. As of November 2025, the resulting SeaStrains Database of European Seaweed Collections contains 2541 cultures representing 426 species, accounting for only 4% of global and 15% of European macroalgal diversity. The dataset reveals strong taxonomic bias: 74% are brown seaweeds (Ochrophyta), dominated by Laminaria, Saccharina, and Ectocarpus. Saccharina latissima is the most preserved species due to its scientific and commercial importance. Red and green algae are markedly underrepresented (11% and 14%, respectively), likely reflecting cultivation challenges and life-cycle knowledge gaps. Biogeographically, most cultures originate from cold- to warm-temperate zones, with limited representation of the South Atlantic, Indian Ocean, polar and remote regions. Over 60% of cultures are maintained at two institutions: the Culture Collection of Algae and Protozoa (Scotland) and the Alfred Wegener Institute (Germany). This work provides transparent, accessible information on Europe’s macroalgal germplasm resources and represents a crucial step toward a more robust and sustainable European seaweed sector aligned with UN SDG Target 2.5.

• Kokkola, Tuukka; Sipkens, Timothy A.; Paul, Andreas; Shukla, Deeksha; Ihalainen, Mika & Das, Anusmita [Show all 25 contributors for this article] (2026). Highly light-absorbing particle emissions from low-sulfur marine fuels. npj Climate and Atmospheric Science. 9(1). doi: 10.1038/s41612-026-01369-w. Full text in Research Archive
• Nadeau, Christina; Milkoreit, Manjana; Dischler, Reidar; Kilsti, Sunneva & Hessen, Dag Olav (2026). Climate dissonance: Examining the relationship between climate beliefs and attitudes toward fossil fuel activities in Norway. Energy Research & Social Science. ISSN 2214-6296. 136. doi: 10.1016/j.erss.2026.104750. Full text in Research Archive Show summary

  To meet the goals of the Paris Agreement and limit anthropogenic global warming to 1.5 °C (or below 2 °C), research indicates that a substantial proportion of the world's remaining fossil fuel reserves must remain unextracted. Despite this, several fossil-producing countries continue to expand hydrocarbon activity. Norway represents a particularly important case because it combines high levels of climate concern with continued support for oil and gas production. Given the intrinsic link between climate change and fossil fuel consumption, one might expect heightened concern about climate impacts to translate into greater support among respondents for restricting further hydrocarbon exploration and extraction. This article examines the relationship between climate change beliefs, political affiliation, and support for fossil fuel extraction in Norway. While many studies have examined climate attitudes or fossil fuel policy preferences independently, this paper addresses how these orientations coexist in a fossil-exporting welfare state, the paradox of strong climate concern alongside continued respondent-level support for fossil fuel production. Drawing on nationally representative survey data collected between 2020 and 2024, this study uses descriptive data from multiple years to show the stability of attitudes over time, while regression analyses focus on the 2024 dataset, which contains the full set of relevant variables and provides the most up-to-date snapshot of respondents' views. It further explores how climate attitudes, political orientation, and support for fossil fuel activities intersect to shape attitudes toward supply-side climate policy. Despite relatively high levels of climate scepticism compared to other Western nations, we find that most Norwegians perceive climate change as a serious issue. However, nearly 90% of respondents still support continued oil and gas production. Climate concern is associated with greater support for restricting future exploration, but not with support for ending existing production, and this relationship is strongly patterned by political affiliation. This paradox places Norway in a state of “climate dissonance”, in which concern about climate change coexists with continued endorsement of fossil fuel activities. As a highly educated nation with a strong environmental reputation yet an economy deeply intertwined with fossil fuel wealth, Norway provides a compelling case for understanding why high levels of climate concern do not necessarily translate into support for fossil fuel phase-out in fossil-fuel-dependent democracies.

• Puts, Isolde Callisto; Mostovaya, A.; Henson, H. C.; Allais, L.; Kluijver, A. de & Thyrring, J. [Show all 8 contributors for this article] (2026). Effects of Meltwater on the Arctic Coastal Microbial Food Web: An Experiment With Isotopic Labeling From Young Sound, NE Greenland. Journal of Geophysical Research (JGR): Biogeosciences. ISSN 2169-8953. 131(3). doi: 10.1029/2025JG008921. Full text in Research Archive
• Kaartvedt, Stein (2026). A career studying fjords and oceans in unconventional ways. ICES Journal of Marine Science. ISSN 1054-3139. 83(3), p. 1–11. doi: 10.1093/icesjms/fsag030. Full text in Research Archive
• Wang, Xinhui; Solhaug, Anita; Garrido, Bruno C.; Mudge, Elizabeth M.; Fon, Mathias & Andersen, Aaron John Christian [Show all 12 contributors for this article] (2026). Structure elucidation of leadbeaterin-1, an ichthyotoxin associated with fish-killing blooms of Chrysochromulina leadbeateri in Northern Norwegian fjords. Harmful Algae. ISSN 1568-9883. 156. doi: 10.1016/j.hal.2026.103104. Full text in Research Archive
• Klöcker, Antonia; Vihtakari, Mikko Juhani; Arostegui, Martin Christopher; Schlindwein, Axel; Ferter, Keno & Bjelland, Otte [Show all 11 contributors for this article] (2026). Wide-ranging, year-round breaching behaviour of basking sharks revealed by long-term biologging. Biology Letters. ISSN 1744-9561. 22(4). doi: 10.1098/rsbl.2025.0696. Full text in Research Archive Show summary

  Marine megafauna, including various species of cetaceans and fishes, exhibit energetically costly breaching behaviour during which individuals rapidly propel themselves out of the water. The function of breaching remains enigmatic, largely due to short-duration observations of limited spatial extent. Here, we used animal-borne biologgers to record breaching events of plankton-feeding basking sharks (Cetorhinus maximus) over full annual cycles at high temporal resolution (5 s) across broad spatial scales (35° latitude). Recording 577 breaches across four individuals over 366 days (mean 144 yr⁻¹ shark⁻¹), breaching appears to be a routine behaviour in both sexes, peaking in autumn, but occurring across all seasons and habitats, including deep oceanic areas. Notably, we identified thermal constraints on breaching rates in colder water, with a critical minimum observed at 5°C. Beyond demonstrating that breaching is more common than previously recognized, our study suggests it serves several functions, some potentially independent of spatial and temporal contexts (e.g. seasonal courtship), such as ectoparasite removal. The ubiquity of breaching across space and time highlights the need for comprehensive ‘behaviour maps’ for ocean giants to elucidate the physiological constraints, ecological significance and management implications of breaching in a changing ocean.

• Wood, Ethan; Edvardsen, Bente; Skjånes, Kari & Supraha, Luka (2026). Phycosphere microbiome succession tracks algal growth dynamics during phosphorus-limited wastewater treatment. Algal Research. ISSN 2211-9264. 95. doi: 10.1016/j.algal.2026.104652. Full text in Research Archive Show summary

  Algal-based wastewater treatment (phycoremediation) relies on microbial interactions within the algal phycosphere that are associated with algal growth and nutrient removal. However, the temporal dynamics of these communities under operational conditions remain poorly resolved. Using 16S and 18S rRNA gene metabarcoding, this study characterized bacterial and eukaryotic communities across alga-attached and free-living size fractions and over time in a raceway-based, pilot-scale phycoremediation system using a filamentous algal co-culture under semicontinuous municipal wastewater flow. Bacterial community composition in the phycosphere overlapped substantially with that observed in a previous laboratory-scale study using the same algal co-culture, with many highly abundant ASVs shared across studies, supporting consistency of key community members across scales. Phycosphere community dynamics were temporally aligned with algal growth, with bacterial alpha diversity in the alga-attached fraction highest during periods of active algal growth and declining with the onset of algal phosphorus limitation. During this high-diversity phase, several orders within Alphaproteobacteria were enriched, followed by declines as the algal culture progressed toward reduced growth. Eukaryotic communities also showed clear successional trends, with Perkinsids (Alveolata) increasing during peak algal biomass before giving way to diverse protists and rotifers. These findings demonstrate coordinated temporal patterns between algal growth dynamics and phycosphere microbial succession in pilot-scale wastewater raceways, providing operational insight into microbial community structure under phosphorus-limited phycoremediation.

• Giebichenstein, Julia; Warner, Nicholas Alexander; Routti, Heli Anna Irmeli; Harju, Mikael; Varpe, Øystein & Gabrielsen, Geir Wing [Show all 7 contributors for this article] (2026). Accumulation patterns of polychlorinated alkanes in an Arctic marine food web. Environmental Research. ISSN 0013-9351. 299. doi: 10.1016/j.envres.2026.124360. Full text in Research Archive Show summary

  Polychlorinated alkanes (PCAs), otherwise known as chlorinated paraffins, are contaminants of emerging Arctic concern where our understanding of their occurrence and trophic transfer in Arctic food webs remains limited. To investigate biomagnification potential of PCAs, we analyzed short-chain PCAs: C10-C13 and medium-chain PCAs-C14-17 in three Arctic species: polar cod (Boreogadus saida), ringed seal (Pusa hispida), and polar bear (Ursus maritimus) and Subarctic capelin (Mallotus villosus) samples collected from the northern Barents Sea in 2017 and 2021. PCAs-C10-13 concentrations were low, but detectable in all species, while PCAs-C14-17 concentrations were mainly below detection limits in the mammals. PCAs did not biomagnify, as the lowest concentrations were found in polar bear (0.7 ng g−1 lw) and the highest in capelin (56.9 ng g−1 lw). The PCA homologue profiles were similar among Arctic species, with PCAs-C10-13 dominating in polar cod and marine mammals, which may suggest a contribution from long-range atmospheric transport. In contrast, PCAs-C14-17 were most abundant in the Subarctic capelin, likely reflecting a different exposure. Despite differing PCAs-C14-17 concentrations among the two fish species, their PCAs-C14-17 homologue profile was similar, indicating uniform global production trends. Subarctic capelin is increasingly being preyed upon by Arctic predators and may facilitate the biological transport of PCAs-C14-17 into Arctic ecosystems. These findings suggest that climate-driven shifts in species distribution may have the potential to alter contaminant exposure pathways in Arctic marine food webs.

• Opdal, Anders Martin Frugård; Alix, Maud; Kjesbu, Olav Sigurd; Jørgensen, Christian; Langangen, Øystein Ole Gahr & Karlsen, Ørjan [Show all 11 contributors for this article] (2026). Despite temperature effects on gonad development, timing of spawning is remarkably flexible in Atlantic cod. ICES Journal of Marine Science. ISSN 1054-3139. 83(2), p. 1–12. doi: 10.1093/icesjms/fsag020. Full text in Research Archive Show summary

  At high latitudes, early life stage survival of fish is often associated with how spawning time relates to the timing of the spring bloom. With ocean warming, basic physiological rates of ectotherms, like fish, will speed up—including gonadal development rates, which dictate spawning time. Since warmer water is thought to influence the spring bloom timing differently than that of fish spawning time, the two may fall out of synchrony in the future. The precise mechanisms between temperature and gonadal development and spawning time have, however, been difficult to disentangle. Here, we take advantage of a series of independent laboratory experiments measuring individual oocyte development up to or near spawning for 153 Atlantic cod (Gadus morhua) kept between 3 and 12°C. From these data we derive a predictive, mechanistic equation for daily oocyte growth rate as a function of temperature and oocyte developmental status (diameter). The vitellogenic oocyte growth follows an accelerating pattern, and the model predicts that spawning can advance by up to 7 days per 1°C increase. Within-treatment variation is, however, of comparable magnitude to between-treatment temperature effects. The model was also tested in the field by back-calculating oocyte development of 82 fish (2018–2021) sampled at two locations along the Norwegian coast, using daily ambient temperatures from telemetry tags during vitellogenesis as model input. We find that Atlantic cod are able to initiate vitellogenesis over a period of several months in late summer and autumn, as well as regulate the oocyte development rate across a wide range of temperatures—both leading to significant phenotypic plasticity in spawning phenology.

• Skjæraasen, Jon Egil; Arechavala-Lopez, P.; Karlsen, Ørjan; Olsen, Esben Moland; Meager, Justin James & Nyqvist, Daniel [Show all 12 contributors for this article] (2026). Male Agonistic Behavior on Atlantic Cod Spawning Grounds. Ecology and Evolution. 16(4). doi: 10.1002/ece3.73316. Full text in Research Archive Show summary

  The mating system of the iconic Atlantic cod (Gadus morhua) has been described as a lek, a mating system where male–male agonistic interactions are expected. However, observing such behaviors directly in marine environments is challenging. So far, the evidence supporting the importance of agonistic interactions between males is mainly derived from laboratory studies with fish kept in close confinement, possibly elevating the observed levels and their perceived importance. In natural aquatic systems, agonistic interactions may be inferred from acoustic telemetry transmitters fitted with accelerometers, given that they are associated with high activity levels. A large telemetry dataset on Atlantic cod was collected during (i) a field study at two Western Norway spawning grounds from 2019 to 2024 and (ii) a close confinement net—pen study in 2019–2020. A total of 154 sexed mature Atlantic cod were tagged with acoustic transmitters fitted with accelerometers and depth sensors, yielding ~1.5 million accelerometer detections for subsequent activity analyses. In the net-pens, male cod showed much higher activity levels than females. Overall activity levels were reduced in the field, but male activity levels remained higher than those of females during the spawning period. A prominent feature of coastal cod spawning along the Norwegian coast is that males tend to dwell deeper than females. We therefore explored whether depth influenced activity patterns of males and females. This was indeed the case with males being more active than females at fish depths > 20 m and no sex-difference in activity levels closer to the surface (< 20 m depth). No sex difference in activity levels was found outside the spawning period. Our data suggest that male–male agonistic interactions, inferred from activity levels, are present on natural spawning grounds for Atlantic cod, albeit at reduced levels compared to levels exhibited in net–pen confinement. We hypothesize that the heightened activity levels of males compared to females when occupying deeper waters are related to their overall deeper distribution and territorial and agonistic behavior at these depths, agreeing with the lek description of the cod mating system.

• Dulgheriu, Daniela; Andvik, Clare Margaret; Jourdain, Eve Marie; Borgå, Katrine; Ruus, Anders & Haug, Tore [Show all 9 contributors for this article] (2026). A sensitive liquid chromatography–tandem mass spectrometry analytical method of steroid hormones in small blubber samples from four whale species. Conservation Physiology. 14(1). doi: 10.1093/conphys/coag023. Full text in Research Archive Show summary

  Steroid hormones can give an indication of stress, physiological health and reproductive status in whales; however, analysis is often limited by sample mass. We developed a sensitive analytical method using solid phase extraction–liquid chromatography–electrospray ionization–tandem mass spectrometry (LC–ESI–MS/MS) for the identification and quantification of eight steroid hormones (cortisol, cortisone, testosterone, androstenedione, progesterone, 11-deoxycortisol, 11-deoxycorticosterone and 17-hydroxyprogesterone) in small amounts of whale blubber (≤50 mg). Blubber biopsies were collected from stranded killer whales (Orcinus orca; n = 7), harbour porpoises (Phocoena phocoena; n = 3) and sperm whales (Physeter macrocephalus; n = 4), harvested common minke whales (n = 10; Balaenoptera acutorostrata) and free-living killer whales (n = 2) in Norway and the Barents Sea. Steroid hormones were separated using pentafluorophenyl propyl stationary phase and an optimized gradient programme with a total 20-min run. All samples (n = 26) were analysed at 50-mg sample mass, and a subset (n = 11) at 25 mg or lower. Low limit of detection and limit of quantification values resulted in high detection rates of hormones, and we found similar hormone concentrations between parallel samples and at the lowest tested sample mass (14 mg). Cortisol concentrations in sperm whales (4.3 ± 1.6 ng/g) were four times higher than stranded killer whales (1.1 ± 0.96 ng/g), which in turn were up to four times higher than free-living killer whales (0.23 ± 0.12 ng/g), harbour porpoise (0.64 ± 0.38 ng/g) and harvested minke whales (0.22 ± 0.13), possibly due to fatality type and duration of stress prior to death. We provide the first quantification of blubber steroid hormones in killer whale, minke whale, sperm whale and harbour porpoise, and in less than 50-mg sample mass. By minimizing sample mass without compromising precision or sensitivity, our method allows for steroid hormone analysis even on samples with limited availability, strengthening our ability to monitor and conserve marine mammal populations.

• Duong, Cuong V.; Ta, Le Minh; Pham, Thanh Thuy Thi; Vu, Ngoc Anh & Dinh, van Khuong (2026). Predatory effectiveness of the copepod Mesocyclops thermocyclopoides on Aedes aegypti larvae: insights for biological control. Pest Management Science. ISSN 1526-498X. doi: 10.1002/ps.70776. Full text in Research Archive
• Calderón-Osorno, Melany; Barrantes-Jiménez, Kenia; Lejzerowicz, Franck Laurent Patrick; Arias-Andres, Maria & Rojas-Jimenez, Keilor (2026). Insights into the riverine metaplasmidome: The role of anthropogenic factors in shaping microbial communities. The Microbe. 10, p. 1–11. doi: 10.1016/j.microb.2025.100640. Full text in Research Archive Show summary

  The environmental plasmidome, encompassing the collective plasmids within an ecosystem, plays a key role in microbial adaptation and evolution. Plasmids, as mobile DNA molecules, enable the transfer of beneficial traits among bacteria, especially in response to environmental stresses. In this study, we developed a novel protocol combining PlasmidSafe DNase and REPLI-g amplification to selectively enrich and characterize plasmidic DNA from polluted environments. We applied this approach to the Virilla River (Costa Rica), a system heavily impacted by urban and industrial activities, analyzing water and sediment samples across seasons and pollution gradients. Our method enabled the recovery of longer, circular contigs confidently identified as plasmids through multiple independent tools, with 28,043 circular sequences primarily linked to Gammaproteobacteria. Contaminated sites, particularly during the rainy season, showed higher plasmid diversity and a marked increase in antibiotic resistance genes (ARGs). This heightened diversity in contaminated environments has implications for the dissemination of antibiotic and metal-resistance genes, as well as other adaptive traits within microbial communities. This research underscores the need to study plasmids in natural environments to better comprehend their ecological roles and potential risks in polluted ecosystems.

• Durant, Joël M.; Langangen, Øystein Ole Gahr; Dolgov, Andrey V.; Lindstrøm, Ulf Ove; Krasnov, Yuri & Nikolaeva, Natalia G. [Show all 7 contributors for this article] (2026). Importance of capelin in the diet of Barents Sea predators relative to alternative prey. Marine Ecology Progress Series. ISSN 0171-8630. 781. doi: 10.3354/meps15078. Full text in Research Archive Show summary

  The Arcto-boreal Barents Sea is significantly impacted by temperature warming, with potential effects on trophic interactions and population dynamics. Capelin, a small pelagic fish species, dominates the Barents Sea’s relatively simple food web. Capelin are an essential link between lower trophic levels and top predators, like in many Arcto-boreal systems. This study investigates the factors controlling capelin consumption by Barents Sea predators. We analysed changes in capelin presence in the diet of predators and related it to capelin and krill abundances, using 8 unique diet data sets from major Barents Sea predators (3 fish, 2 seabird, and 2 marine mammal species) spanning 10-36 yr. Only 2 fish species showed a positive relationship between the percentage of capelin in the stomach and capelin abundance, while all fish species exhibited a negative correlation with krill abundance. This finding suggests that these species replace capelin with krill in their diet based on prey availability. Our results confirm the central role of capelin in the Barents Sea ecosystem, with most predators’ diets being influenced by that species’ abundance. Krill plays a more significant role in the Southern Barents Sea, particularly for central place foragers. Although diet data can have limitations, our study shows that diet analysis remains a valuable method to study predator-prey relationships. This information is essential for understanding predator-prey dynamics of key species in the Barents Sea, supporting ecosystem-based and multi-species fisheries management efforts under current and future climate conditions.

• Langangen, Øystein Ole Gahr; Kaartvedt, Stein; Hylland, Ketil & Durant, Joël (2026). The collapse of Atlantic cod in the Oslofjord. Frontiers in Marine Science. 13. doi: 10.3389/fmars.2026.1746235. Full text in Research Archive Show summary

  Coastal fish populations in temperate regions increasingly experience environmental pressures and dramatic decreases in stock size. Currently, there are serious concerns about the status of the Atlantic cod ( Gadus morhua ) in the Oslofjord region, a 120-km inlet in southeastern Norway. Given the recent political debate, the large public interest, and the recent decision to close large areas in the Oslofjord to all fishing, the scarcity of quantitative estimates on cod biomass in the region presents an acute challenge. Typically, the state of the cod in the Oslofjord has been assessed by the analysis of juvenile fish datasets. However, scientific surveys targeting adult life stages are limited, and abundance and biomass estimates are based on relatively short time series and with limited spatial coverage. Here, we demonstrate how commercial landings data can be used to describe a recent decline in catch per unit effort in the region, a proxy related to biomass. These results are highly topical and can serve as a baseline for further investigations on the reasons for the collapse of the cod population. While our results demonstrate the value of the large commercial dataset, the introduction of conservation actions calls for alternative and more comprehensive monitoring in the area for documenting a potential future recovery. Our results highlight research and data needs associated with current efforts to improve the status of fish stocks in general, and the Atlantic cod in the Oslofjord in particular.

• Goraguer, Lucie Helene Marie; Marquardt, Miriam; Gradinger, Rolf Rudolf; Kohlbach, Doreen; Reigstad, Marit & Assmann, Karen [Show all 17 contributors for this article] (2026). Environmental drivers shaping protist plankton seasonality in the northwestern Barents Sea. Progress in Oceanography. ISSN 0079-6611. 244. doi: 10.1016/j.pocean.2026.103702. Full text in Research Archive Show summary

  Unicellular marine eukaryotes (protists) are important components of the biological carbon pump and form the base of marine food webs, ultimately supporting commercially important fish stocks. However, seasonally resolved data on protist composition, abundance and biomass are rare, especially in high latitude ice-covered oceans. This study presents unique seasonal data on protist community composition and abundance from the northwestern Barents Sea, spanning a latitudinal gradient from open Atlantic waters south of the Polar Front to the seasonally ice-covered Barents Sea shelf and across the shelf break into the Arctic Nansen Basin. Observations were conducted during seven cruises (2018 to 2022) covering periods from early winter to late summer. Protist standing stocks and community composition exhibited pronounced seasonality. Dinoflagellates, particularly Gymnodinium species, dominated the low protist stocks in winter whereas summer communities were more diverse and characterized by dinoflagellates, ciliates and flagellates. Mixo- and heterotrophic feeding modes enable these taxa to persist through the polar night and thrive during the stratified and nutrient-poor conditions in summer. Seasonal differences between dinoflagellates and ciliates likely reflect contrasting feeding and survival strategies. The onset of the phytoplankton spring bloom, dominated by rapidly growing centric diatoms of the genera Thalassiosira and Chaetoceros, occurred in a deeply mixed water column in both open and ice-covered waters. This may have been facilitated by diatoms’ effective defense against protozoan grazers and temporal mismatch between the phytoplankton spring bloom and copepod grazers in Atlantic influenced waters. Our seasonally resolved observations highlight the strong seasonality in both the quantity and quality of protist plankton in the Barents Sea, dynamics which will likely shift with the ongoing decline in sea-ice cover.

• Jamy, Mahwash; Ramond, Pierre; Bass, David; Campo, Javier del; Dunthorn, Micah & Lara, Enrique [Show all 9 contributors for this article] (2026). Towards a trait-based framework for protist ecology and evolution. Trends in Microbiology. ISSN 0966-842X. 34(3), p. 242–251. doi: 10.1016/j.tim.2025.08.008. Full text in Research Archive Show summary

  Protists comprise the vast majority of eukaryotic genetic and functional diversity. While they have traditionally been difficult to study due to their small size and varied phenotypes, environmental sequencing studies have revealed the stunning diversity and abundance of protists in all ecosystems. Protists are key primary and secondary producers across many biomes, with ecological specializations that range from mutualism to parasitism, complex predation behaviors, mixotrophy, detritivory, and saprotrophy. Current genomic and transcriptomic approaches provide valuable insights into protist diversity at the genetic level, but they fall short in capturing the morphological and behavioral traits critical for understanding the functional roles of protists in ecosystems. This knowledge gap hinders our ability to answer important questions about protist functional diversity, including how protist functional groups will respond to environmental change. In this opinion article, we advocate adopting a traits-based approach for studying protist diversity and developing a trait database for protists to support this goal. By integrating examples of recent work characterizing protist functional diversity using a range of approaches, we emphasize the opportunities that trait databases offer and propose strategies for moving towards a trait-based framework to guide future research in protist ecology and evolution.

• Nguyen, Tan Duc; Nguyen, Van Tai; Dinh, van Khuong; Wiegand, Claudia; Wang, Zhen & Baduel, Christine [Show all 13 contributors for this article] (2025). Multigenerational ecotoxicity of tris(2-butoxyethyl) phosphate to the tropical water flea Ceriodaphnia cornuta and probabilistic ecological risk assessment in freshwater environments. Aquatic Toxicology. ISSN 0166-445X. 283. doi: 10.1016/j.aquatox.2025.107363. Full text in Research Archive
• Nguyen, Tan Duc; Huynh, Trong Nhan; Nguyen, Van Tai; Dinh, van Khuong; Wiegand, Claudia & Pham, Thanh Luu [Show all 11 contributors for this article] (2025). Multigenerational testing reveals delayed chronic toxicity of bisphenol A to Daphnia magna: A common characteristic of endocrine-disrupting chemicals? Environmental Pollution (1987). ISSN 0269-7491. 374. doi: 10.1016/j.envpol.2025.126253. Full text in Research Archive
• Pham, Hung Quoc; Le, Hoang Minh; Phan, Ut Van; Nguyen, Minh Van & Dinh, van Khuong (2025). Seasonal dynamics of plasma estradiol 17β level, gonadosomatic index, and ovarian development in female golden trevally (Gnathanodon speciosus). Scientific Reports. 16. doi: 10.1038/s41598-025-30370-1. Full text in Research Archive Show summary

  Plasma estradiol 17β (E2) and gonadosomatic index (GSI) are reliable biomarkers for assessing gonadal maturity in fish. This study investigated seasonal variations in GSI and plasma E2 concentrations and their correlation with ovarian development stages in female golden trevally (Gnathanodon speciosus), a high-value fish species for marine aquaculture, over an annual reproductive cycle. The broodfish were 900 ± 200 g and 40 ± 5 cm in body weight and total length, respectively. From November to February, plasma E2 levels and GSI remained low, followed by a significant increase from March to October, with E2 peaking during vitellogenesis. Ovarian histology revealed asynchronous oocyte development from March to October, with multiple oocyte stages coexisting, confirming G. speciosus as a multiple-spawning species with a reproductive season spanning March to October. Elevated plasma E2 levels during oocyte growth underscore its pivotal role in driving vitellogenesis. These findings enhance understanding of G. speciosus reproductive physiology, providing valuable insights for optimizing broodstock management, conditioning protocols, and strategic planning for artificial reproduction and seed production for marine aquaculture.

• Buhhalko, Natalja; Kuddithamby, Gunaalan; Vianello, Alvise; Rotander, Anna; Vidal-Liñán, Leticia & Beiras, Ricardo [Show all 19 contributors for this article] (2025). Microplastics (10 µm-5 mm) in European Atlantic Coastal Waters. Environmental Advances. 21, p. 14–14. doi: 10.1016/j.envadv.2025.100644. Full text in Research Archive Show summary

  Microplastics (MPs) are pervasive pollutants in coastal waters, raising significant ecological concerns. This study assessed the abundance and characteristics of small-sized MPs (down to 10 µm) across European Atlantic coastal sites using harmonized sampling and analytical methods. A filter-pump microplastic sampler, the "Universal Filtering Object" (UFO), was employed at all sites, with Manta net (300-µm mesh) sampling conducted at selected locations. Microplastic concentrations ranged from <10 MPs m-3 to >1600 MPs m-3, with the Gulf of Finland showing the lowest concentration (5 MPs m-3) and the Scheldt estuary in Belgium the highest (1603 MPs m-3). Most MPs (80%) were <300 µm, primarily consisting of polyester, polypropylene, and polyethylene fragments. Manta net sampling consistently underestimated both total microplastic concentrations and microplastics larger than 300 µm compared to UFO sampling. Estuaries and wastewater effluents were identified as pollution hotspots, strongly influencing local MP distributions. The median microplastic concentration found in European Atlantic waters in this study was lower than the global median for coastal waters measured using pump-based sampling devices. Although current MP levels are unlikely to pose an immediate risk to the marine pelagic food web, the projected increase in plastic production, combined with its low degradability and chemical leaching, underscores the urgency of implementing mitigation measures to prevent future environmental impacts.

• Tabane, F; Cazier, F; Dewaélé, D; Hylland, Ketil; Ba, CT & Fall, M (2025). Evaluating the histopathology, condition index and stress-on-stress response of caged brown mussels Perna perna for monitoring marine coastal pollution in Senegal. African Journal of Marine Science. ISSN 1814-232X. 47(2), p. 129–141. doi: 10.2989/1814232x.2025.2485075. Full text in Research Archive Show summary

  This study is the first in a coastal West African country to evaluate the histopathology, condition index and stress-on-stress response time of caged brown mussels Perna perna for use in pollution monitoring of coastal ecosystems. Perna perna collected from an unpolluted area on the coast of Senegal were divided and transplanted to a polluted site or maintained at the reference site for an exposure–depuration experiment. After 4 weeks of exposure, the mussels deployed at the polluted site (Port of Dakar) were then transferred to the cleaner reference site (Pointe des Almadies) for depuration. Mussels exposed to the polluted waters of the seaport had bioaccumulated polycyclic aromatic hydrocarbons (PAHs) as well as lead, copper and selenium; furthermore, changes were observed in their digestive gland histology, and their stress-on-stress response measured as median survival time (LT50) had decreased. By the end of the 4-week depuration period at the reference site the mussels showed signs of recovery, specifically in terms of their digestive tubule architecture and tolerance to air exposure. The results demonstrate that caged P. perna could be used as bioindicators for monitoring coastal environmental pollution in West Africa.

• Shukla, Deeksha; Czech, Hendryk; Kokkola, Tuukka; Bauer, Martin; Paul, Andreas & Etzien, Uwe [Show all 18 contributors for this article] (2025). Emission speciation of volatile and intermediate volatility organic compounds from a marine engine: effect of engine load, fuel type and photochemical aging. Environmental Science: Atmospheres. ISSN 2634-3606. 5(9), p. 973–986. doi: 10.1039/d5ea00040h. Full text in Research Archive
• Garvang, Even Sletteng; Heuschele, Jan David; Konestabo, Heidi Sjursen; Andersen, Tom; Riemann, Lasse & Titelman, Josefin (2025). Parasite infection shapes the pathobiome and behavior of marine zooplankton. Limnology and Oceanography Letters. 11(1). doi: 10.1002/lol2.70078. Full text in Research Archive Show summary

  When assessing the total impact of disease in a host, it is important to consider not only the disease‐carrying agent but also all symbionts, as they affect and are affected by the course of disease. This concept of a pathobiome is increasingly recognized in disease ecology, but is not well‐investigated in natural systems. Copepods are key organisms in marine ecosystems and host a variety of symbionts, including bacteria and eukaryotic parasites. We investigated the impact of a taxonomically uncertain yellow‐hyphal parasite (YHP) on its copepod host Calanus helgolandicus with an incubation experiment, comparing survival, behavior, and microbiomes of uninfected and infected hosts. Infected hosts suffered higher mortality, and altered behavior which can increase predation risk. The microbiomes differed between infected and uninfected hosts, likely caused by a combination of direct effects of infection, and environmental effects driven by parasite‐induced behavioral change. We identified several potential contributing taxa to the Calanus ‐YHP pathobiome using model‐based ordination.

• Hartikainen, Anni; Ihalainen, Mika; Shukla, Deeksha; Rohkamp, Marius; Mukherjee, Arya & He, Quanfu [Show all 30 contributors for this article] (2025). Photochemical aging of aviation emissions: transformation of chemical and physical properties of exhaust emissions from a laboratory-scale jet engine combustion chamber. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 25(16), p. 9275–9294. doi: 10.5194/acp-25-9275-2025. Full text in Research Archive
• González-Miguéns, Rubén; Gàlvez-Morante, Àlex; Skamnelou, Margarita; Antó, Meritxell; Casacuberta, Elena & Richter, Daniel J [Show all 10 contributors for this article] (2025). A novel taxonomic database for eukaryotic mitochondrial cytochrome oxidase subunit I gene (eKOI), with a focus on protists diversity. Database: The Journal of Biological Databases and Curation. 2025. doi: 10.1093/database/baaf057. Full text in Research Archive Show summary

  Metabarcoding has emerged as a robust method for assessing biodiversity patterns by retrieving environmental DNA directly from ecosystems. While the 18S rRNA gene is the primary genetic marker used for broad eukaryotic metabarcoding, it has limitations in resolving lower taxonomic levels. A potential alternative is the mitochondrial cytochrome oxidase subunit I (COI) gene because it offers resolution at the species level. However, the COI gene lacks a comprehensive, curated taxonomically informed database including protists. To address this gap, we introduce eKOI, a novel, curated COI gene database designed to enhance the taxonomic annotation for protists that can be used for COI-based metabarcoding. eKOI integrates data from GenBank and mitochondrial genomes, followed by extensive manual curation to eliminate redundancies and contaminants, recovering 15 947 sequences within 80 eukaryotic phyla. We validated the use of eKOI by reannotating several COI metabarcoding datasets, revealing previously unidentified protist biodiversity and demonstrating the database utility for community-level analyses.

• Sim, Clarence Wei Hung; Ribeiro, Catherine Gérikas; Gall, Florence Le; Probert, Ian; Gourvil, Priscilla & Lovejoy, Connie [Show all 8 contributors for this article] (2025). Temporal dynamics and biogeography of sympagic and planktonic photosynthetic microbial eukaryotes during the under-ice Arctic bloom. ISME Communications. 5(1). doi: 10.1093/ismeco/ycaf075. Full text in Research Archive Show summary

  Photosynthetic microbial eukaryotes play a pivotal role as primary producers in the Arctic Ocean, where seasonal blooms within and below the ice are crucial phenomena, contributing significantly to global primary production and biogeochemical cycling. In this study, we investigated the taxonomic composition of sympagic algae and phytoplankton communities during the Arctic under-ice spring bloom using metabarcoding of the 18S rRNA gene. Samples were obtained from three size fractions over a period of nearly three months at an ice camp deployed on landfast ice off the coast of Baffin Island as part of the Green Edge project. We classified the major sympagic and phytoplankton taxa found in this study into biogeographical categories using publicly available metabarcoding data from more than 2800 oceanic and coastal marine samples. This study demonstrated the temporal succession of taxonomic groups during the development of the under-ice bloom, illustrated by an overall transition from polar to polar-temperate taxa, particularly in the smallest size fraction. Overlooked classes such as Pelagophyceae (genera Plocamiomonas and Ankylochrysis), Bolidophyceae (Parmales environmental clade 2), and Cryptophyceae (Baffinella frigidus) might play a greater role than anticipated within the pico-sized communities in and under the ice pack during the pre-bloom period. Finally, we emphasize the importance of microdiversity, taking the example of B. frigidus, for which two ecotypes linked to pelagic and sea ice environments have been identified.

• Otte, Antonia; Wohlrab, Sylke; Moritz, Franco; Müller, Constanze; Janouskovec, Jan & Michálek, Jan [Show all 14 contributors for this article] (2025). High-resolution multiomics links nutrients and mixotrophy to toxicity in a harmful bloom of the haptophyte Chrysochromulina leadbeateri. Science Advances. 11(26). doi: 10.1126/sciadv.adv3390. Full text in Research Archive Show summary

  Harmful algal blooms (HABs) of the toxigenic haptophyte Chrysochromulina are known to cause fish mortalities and collateral ecosystem damage. The ichthyotoxic mechanisms are poorly understood but likely dependent on toxigenesis by polyketide synthases (PKSs). We hypothesize that induction of PKS activity facilitates mixotrophic behavior during nutrient-depleted bloom conditions. To identify potential in situ stimuli for growth, toxigenicity, and bloom persistence, we compared environmental factors and biological processes identified by metaomics to Chrysochromulina leadbeateri HABs between two fjords in northern Norway. We identified the polyketide ichthyotoxin leadbeaterin-1 from the C. leadbeateri bloom and found potentially associated candidate PKS genes of which most were higher expressed at bloom stations. A relative depletion of inorganic nitrogen and phosphate during the bloom was correlated with higher expression of genes involved in endocytosis, autophagy, and lysosomal activity. Mixotrophy is evidently a compensatory nutritional strategy coupled to induction of toxigenesis and other metabolomic processes as biotic factors linked to Chrysochromulina bloom dynamics.

• Lutier, Mathieu; Skari, Andrea Emilie Thorstensen; Thomsen, Nele; Reinardy, Helena Christine & Dinh, van Khuong (2025). The Arctic copepod Calanus hyperboreus is more tolerant to marine heatwaves than temperate copepods in the Oslofjord. Royal Society Open Science. 12(10), p. 1–10. doi: 10.1098/rsos.250365. Full text in Research Archive Show summary

  Calanus hyperboreus plays a key role in the functioning of Arctic ecosystems. It is considered highly vulnerable to ocean warming and marine heatwaves, which would reduce its range, expected to shift northward. Yet, C. hyperboreus is reported as far south as the Skagerrak, where it is considered non-native and transported by ocean currents. We argue that this may be an isolated population adapted to warmer temperatures. To test this hypothesis, we exposed C. hyperboreus from the Oslofjord to temperatures from 0°C to 24°C, for 5 days. We recorded survival to identify the upper threshold of thermal tolerance and DNA damage to detect sublethal effects. The thermal response of C. hyperboreus was compared with that of the dominant copepod species in the Oslofjord, Calanus finmarchicus and Metridia longa . We found that the survival of C. hyperboreus did not decrease before reaching 16°C–20°C which was much higher than 13°C–16°C and 4°C–8°C for C. finmarchicus and M. longa , respectively. Calanus hyperboreus showed the least DNA damage, highlighting the adaptation of its physiology to the Oslofjord. Our results suggest the existence of local adaptations to warming in C. hyperboreus that could determine its fate under climate change.

• Olsen, Tora; Stige, Leif Christian; Dupont, Nicolas; Durant, Joël M & Langangen, Øystein Ole Gahr (2025). Reply to Bogstad et al. (2025) ‘Comment on “Repeated large declines in the Barents Sea capelin populations are associated with different ecosystem conditions” by Olsen et al. (2024)’. ICES Journal of Marine Science. ISSN 1054-3139. 82(4). doi: 10.1093/icesjms/fsaf054. Full text in Research Archive Show summary

  Herring predates on young capelin in the Barents Sea (BS), which affects the recruitment of BS capelin. However, our modelling study does not support the hypothesis that Bogstad et al. advocated that herring predation is necessary for the observed large declines (collapses) of the BS capelin population. What Bogstad et al. do not consider is the magnitude of the herring predation effect compared to other influences on the population dynamics of capelin. Our results suggest that while herring significantly reduced age-0 abundance of capelin at the start of the collapses, these reductions were probably not the main cause of the subsequent large population declines. All models have limitations, but we do not agree with Bogstad et al. that model limitations were the reason for our findings on the importance of herring predation for capelin biomass collapses.

• Eikefjord, Mathilde Bryn; Johannesen, Edda; Reecht, Yves; Fall, Johanna; Staby, Arved & Langangen, Øystein Ole Gahr [Show all 7 contributors for this article] (2025). Contrasting latitudinal patterns in spawning phenology of three gadoids in the northeast Atlantic. ICES Journal of Marine Science. ISSN 1054-3139. 82(10), p. 1–13. doi: 10.1093/icesjms/fsaf186. Full text in Research Archive Show summary

  The timing of phytoplankton spring blooms varies geographically, typically with later blooms occurring at higher latitudes. This is expected to lead to a latitudinal gradient in timing of spawning of species that depend on synchronizing spawning with the spring bloom to optimize larval feeding opportunities. Here, we contrast and compare spatial variation in spawning phenology of cod (Gadus morhua), haddock (Melanogrammus aeglefinus), and saithe (Pollachius virens) in three areas spanning from the North Sea in the south to the Barents Sea in the north. Data on macroscopically determined gonadal development stages were obtained from fish collected by research surveys and by fishing vessels. We found evidence of active spawning over extensive areas, including areas outside the currently recognized spawning grounds. Among the three species, haddock spawned the latest in all areas, and saithe earliest, except in the North Sea, where cod spawned first. Size-related differences in peak spawning were only observed in the south for cod and saithe, and in the north for haddock, with smaller fish spawning later. However, the results on size were associated with high uncertainty. Consistent with the expectation, the peak of the spawning season for cod and haddock was later at higher latitudes. In contrast, the latitudinal variation in spawning time in saithe was limited. Our results illustrate the need for both species and region-specific investigations of spawning phenology, as it may affect recruitment dynamics, especially under climate change, and have implications for survey design, stock assessment, and ultimately, population persistence.

• Eliassen, Lasse Krøger; Altin, Dag; Andersen, Tom; Riemann, Lasse; Dunthorn, Micah & Titelman, Josefin (2025). Long Term Copepod Culture Houses a Rich Microbial Eukaryotic Community Including New and Known Symbionts. Journal of Eukaryotic Microbiology. ISSN 1066-5234. 72(6). doi: 10.1111/jeu.70053. Full text in Research Archive Show summary

  Copepods, dominant marine zooplankton, are hosts to microbial eukaryotic symbionts, but the copepod eukaryome remains largely unexplored. We used 18S rRNA gene primers with reduced metazoan amplification to identify microbial eukaryotes in a culture of Calanus finmarchicus (Copepoda). Samples were taken from the inlet water (99.5% of reads from non‐copepod sources) and the contents of the culture, which included ambient water (99.7%), bulk (many crushed copepods, 60.2%), individual copepods (1%–41%, mean = 7.4), and bulk fecal pellets (74%). The microbial eukaryotic community in the culture differed from the inlet water. The culture contained saprotrophs and bacterivores typical of eutrophic aquacultures and known parasites of copepods. Individual copepod eukaryomes varied in richness (8–33 operational taxonomic units, mean = 16.1) and revealed variation in non‐copepod read yields related to specific taxa. Perkinsea, not previously reported in copepods, as well as Ascomycota and Basidiomycota (Fungi), formed the core eukaryome (found in > 90% of individuals), indicating potentially important symbiosis. The small eukaryome, relative to reported microbiomes in C. finmarchicus , suggests that ecological inferences from microbiomes, which largely address bacteria, are not readily applicable to the eukaryotic microbes. The study underpins the need for investigations of eukaryomes.

• Grytting, Vegard Sæter; Kirkerød, Elisabeth; Skuland, Tonje Schwach; Refsnes, Magne Arnold; Låg, Marit & Sadiktsis, Ioannis [Show all 9 contributors for this article] (2025). Pro-inflammatory effects of road wear particles and diesel exhaust particles in bronchial epithelial cells and macrophages. Environmental Research. ISSN 0013-9351. 283. doi: 10.1016/j.envres.2025.122134. Full text in Research Archive
• Vereide, Emilie Hernes; Utne-Palm, Anne Christine; Titelman, Josefin; Pedersen, Geir; Strand, Espen & Mihaljevic, Marina [Show all 13 contributors for this article] (2025). Zooplankton mortality and distribution around a seismic survey. Scientific Reports. 15. doi: 10.1038/s41598-025-09465-2. Full text in Research Archive Show summary

  Anthropogenic underwater noise from seismic airguns is increasing, posing a potential threat to marine life. Despite their ecological importance, knowledge of the impacts of seismic surveys on zooplankton remains limited. In the North Sea, we utilized various methods to assess potential effects on zooplankton around an ongoing seismic survey. A seismic airgun array (3060 inch3) performed a survey along parallel lines, while we sampled from a research vessel positioned at the end of three of these lines. The airgun-generated noise reached a maximum broadband sound exposure level of 182 dB re 1µPa2s at the closest proximity (~50&nbsp;m). Zooplankton biomass exhibited a consistent distribution in line with hydrography and chlorophyll distribution, before and after airgun exposure. Immediate mortality in Calanus spp. was uniform across sound levels, never exceeding 35.9%. Cultured Calanus finmarchicus were exposed while submerged in bags. These displayed low immediate mortality (&lt;10%), with an increasing trend (&lt;30%) up to 7 days post-exposure. These findings highlight the interplay between sound exposure, environmental conditions, and the impact on zooplankton in areas of seismic activity, indicating that immediate impacts of seismic surveys on zooplankton may be limited. However, delayed impacts that could lead to population effects require further investigation.

• Graves, Stephanie D.; Kidd, Karen A.; Arts, Michael T.; Braaten, Hans Fredrik Veiteberg; Wit, Heleen de & Borgå, Katrine [Show all 8 contributors for this article] (2025). Terrestrial carbon inputs drive methylmercury accumulation in zooplankton of boreal and subarctic lakes. Limnology and Oceanography. ISSN 0024-3590. 70(10), p. 2910–2923. doi: 10.1002/lno.70185. Full text in Research Archive Show summary

  Boreal and subarctic lakes are subject to the climate‐sensitive process of browning, whereby transport of terrestrial dissolved organic matter (tDOM) to lakes results in greater dissolved organic carbon (DOC) concentrations and associated darker water color. Increasing tDOM will increase mercury (Hg) transport to these lakes, but whether this leads to greater methylHg (MeHg) bioaccumulation in food webs remains unclear. We determined whether increasing DOC increased MeHg bioaccumulation in the lower food web (i.e., zooplankton) by measuring a suite of water chemistry characteristics (including aqueous MeHg and DOC) along with stable isotopes of C (δ 13 C) and N (δ 15 N), fatty acid (FA) profiles, and MeHg content of zooplankton from 16 Scandinavian boreal and subarctic lakes along a DOC gradient in the Fall of 2016. We found that both aqueous and zooplankton MeHg were positively correlated with DOC concentration, and that DOC and zooplankton MeHg both increased with the bacterial FA marker 18:1n‐7 and decreased with docosahexaenoic acid (DHA) : arachidonic acid and DHA : eicosapentaenoic acid ratios in zooplankton, which are indicators of diet or taxonomic composition. Zooplankton MeHg content was best predicted by δ 13 C and the FA 18:1n‐7, indicating that zooplankton MeHg bioaccumulation in zooplankton was associated with changes in their resource use along a DOC gradient. Our results suggest that lake browning will likely lead to an increase in MeHg bioaccumulation in zooplankton by affecting aqueous MeHg exposure and lower food web dynamics. In turn, this may lead to increased MeHg contamination in fish and other wildlife.

• García-Seoane, Eva; Gjøsæter, Harald; Dalpadado, Padmini & Kaartvedt, Stein (2025). Why is the Arabian Sea a hotspot for myctophids? Fisheries Research. ISSN 0165-7836. 288. doi: 10.1016/j.fishres.2025.107453. Full text in Research Archive Show summary

  Myctophids are the dominant mesopelagic fishes in most of the world’s oceans. They play a key ecological role and also have a potential for harvest. We here synthesize general traits of myctophid biology and address the success and life history strategy of the dominant myctophid species in the mesopelagic hotspot of the Arabian Sea. In this ocean, the biomass of myctophids is particularly high, but dominated by only a few species. With low abundance of competing small pelagic fish, much of the high production is channeled via zooplankton to the stocks of mesopelagic fishes. The ability of the successful species to tolerate low oxygen levels facilitates exploitation of these productive waters and reduces competition for prey. Simultaneously, the hypoxic waters provide refuge from predators. The myctophids in the Arabian Sea feed in warm waters at night and inhabit cooler, yet relatively warm waters during daytime. We hypothesize that this temperature regime combined with a high abundance of prey provides a favorable combination of foraging and digestion. To this adds that the location near the Equator provides a year-long favorable regular shift between length of day and night for foraging in upper waters and digestion in deep waters, though digestion may be constrained by low oxygen concentrations. Myctophid species from tropical habitats have shorter life spans than species from colder regions. We suggest that in tropical habitats, such as the Arabian Sea, extended spawning seasons are common for myctophids whereas restricted spawning seasons are more common in cold-water habitats. The Gulf of Oman, which is the upwelling region with the highest primary production in Indian Ocean, is recognized to have the greatest potential for any commercial exploitation of mesopelagic fish.

• Vindenes, Yngvild; Broch, Catharina; Andersen, Tom; Hessen, Dag Olav & Ergon, Torbjørn (2025). Understanding the role of ageing in the thermal responses of life history and fitness in Daphnia magna. Proceedings of the Royal Society of London. Biological Sciences. ISSN 0962-8452. 292(2051). doi: 10.1098/rspb.2025.0430. Full text in Research Archive Show summary

  The current climate warming has raised concerns that increased rates of ageing will lead to reduced fitness and population viability in ectotherms. However, it is currently not known whether temperature effects on the rate of ageing mainly reflect a change in pace of life or changes in the strength of ageing in the life history. Evaluating this question requires that ageing in different temperatures is compared on the same intrinsic pace-standardized time scale. We present results from a laboratory experiment with Daphnia magna , recording complete life histories of 240 individuals from four clonal lines at six temperatures (5°C to 30°C). For each clone and temperature, we calculated measures of pace and shape of ageing in survival and reproduction. Fitness (long-term population growth rate) and mean lifetime reproduction were calculated using matrix population models. Our results highlight three main points: (i) lifespan is not a good predictor of temperature effects on ageing; (ii) there is no strong consistent effect of temperature on shape of ageing; and (iii) within temperature, the shape of ageing was positively correlated with fitness. Hence, lower fitness and population viability of ectotherms in warmer environments may be driven by factors other than increased ageing rates.

• Langangen, Øystein Ole Gahr; Olsen, Tora; Ottersen, Geir; Eriksen, Elena & Durant, Joël M. (2025). Consequences of climate-related poleward shifts in cod spawning. Canadian Journal of Fisheries and Aquatic Sciences. ISSN 0706-652X. 82, p. 1–11. doi: 10.1139/cjfas-2024-0380. Full text in Research Archive Show summary

  With climate change, many species alter their distribution according to local climate velocities. For marine fish, suitable areas for spawning in a warming climate may be less favorable for the resulting offspring, e.g., the sensitive larval and juvenile phases. The size of the young-of-the-year before their first winter is an important factor for subsequent survival, year class formation, and population dynamics of many fish species and populations. Here, we investigate how the change in spawning location of the Barents Sea population of Atlantic cod ( Gadus morhua) may affect the mean individual size of the offspring in their first fall. We demonstrate how the observed climate warming-related northerly shift in spawning location may lead to smaller sizes of young-of-the-year cod. Our analysis reveals a positive effect of sea temperature on offspring size and a nonlinear effect of spawning stock biomass (SSB) with smaller offspring size at both the high and low end of SSB. Decreased offspring size is likely to affect population dynamics through reduced recruitment success, and we hypothesize that it may have been part of the reason for this population's recent reduction in biomass.

• Eriksen, Elke; Graff, Pål; Eiler, Alexander; Straumfors, Anne & Afanou, Komlavi Anani (2025). DNA metabarcoding and its potential in microbial risk assessment in waste sorting plants. Scientific Reports. 15(1). doi: 10.1038/s41598-025-93697-9. Full text in Research Archive Show summary

  Exposure to hazardous microorganisms during waste handling is a potential health concern. Molecular biological techniques provide means of profiling the microbial community at high taxonomic resolution, allow the identification of critical human pathogens on the species level and thereby aid the risk assessment of work tasks. The present study used high-throughput sequencing to characterise the microbiome in personal full-shift air samples collected at contemporary waste sorting plants (WSPs) and identified large variations in community composition within (alpha diversity) and between (beta diversity) WSPs. Seasonality did not contribute to differences in the community composition. Cladosporium sp. was dominant among fungi, whereas Aerococcus sp. was dominant among bacteria. The personal air-samples contained potential human pathogens, such as Aspergillus sp., Fusarium sp. and Enterobacteriaceae, that encompass strains with the potential to develop drug-resistance. This study provided characterization of the microbial community composition of personal bioaerosol samples and provided evidence for the occurrence of potential human pathogens in contemporary waste sorting plants. Furthermore, this study highlighted the potential of microbial metabarcoding to detect critical human pathogens that may be encountered in working environments.

• Årthun, Marius; Dinh, van Khuong; Dörr, Jakob Simon; Dupont, Nicolas; Fransner, Filippa & Nilsen, Ina [Show all 18 contributors for this article] (2025). The future Barents Sea- A synthesis of physical, biogeochemical, and ecological changes toward 2050 and 2100. Elementa: Science of the Anthropocene. 13(1), p. 1–17. doi: 10.1525/elementa.2024.00046. Full text in Research Archive Show summary

  Barentshavet er preget av sterke klimaendringene, som manifesterer seg i en rask oppvarming av havet og atmosfæren og en sterk nedgang i havisdekket om vinteren. Disse endringene i det fysiske miljøet har store konsekvenser for de marine økosystemene, inkludert de kommersielle fiskebestandene. I et varmere klima i fremtiden forventes både de fysiske og økologiske endringene å forsterkes. Her gir vi en første omfattende oversikt over framtidige klimaendringer i Barentshavet og de tilhørende fysiske, biogeokjemiske og økologiske konsekvensene basert på klimamodeller og helhetlige økosystemmodeller. Vi diskuterer også potensielle fremtidige endringer i menneskelige aktiviteter og konsekvensene av disse, inkludert endringer i skipsaktivitet og forurensing. Vi analyserer resultatene for to tidshorisonter - nær fremtid (2040-2050) og fjern fremtid (2090-2100) - og for to ulike utslippsscenarioer: ett med moderate fremtidige klimagassutslipp (SSP2-4,5) og ett med høye utslipp (SSP5-8,5). Resultatene viser at fremtidens Barentshavet vil bli varmere, mindre isdekket, surere og mer produktivt, og at fiskebestander og gyteområder vil flytte seg nordover. Det er små forskjeller i de gjennomsnittlige fysiske og biogeokjemiske projeksjonene fra flere modeller mellom de to utslippsscenariene innen 2050, mens det er store forskjeller mellom scenariene mot slutten av århundret. Disse resultatene har vidtrekkende konsekvenser, blant annet ved at de kan identifisere økosystemenes følsomhet for fremtidige utslipp, gi informasjon om regionale forvaltningsstrategier og potensielt identifisere behov for tilpasning til endringer som sannsynligvis allerede vil inntreffe.

• Egge, Elianne Dunthorn; Vaulot, Daniel; Larsen, Aud & Edvardsen, Bente (2025). The community of marine alveolate parasites in the Atlantic inflow to the Arctic Ocean is structured by season, depth, and water mass. Arctic Science. ISSN 2368-7460. 11, p. 1–16. doi: 10.1139/as-2024-0016. Full text in Research Archive Show summary

  The marine alveolates (MALVs) are a highly diverse group of parasitic dinoflagellates, which may regulate populations of a wide range of hosts, including other dinoflagellates, copepods, and fish eggs. Knowledge on their distribution and ecological role is still limited, as they are difficult to study with morphological methods. In this work, we describe the taxonomic composition and seasonal and depth distribution of MALVs in the Arctic Ocean west and north of Svalbard, based on 18S V4 rRNA metabarcoding data from five cruises. We recovered amplicon sequence variants (ASVs) representing all major groups previously described from environmental sequencing studies (Dino-Groups I–V), with Dino-Groups I and II being the most diverse. The community was structured by season, depth, and water mass. In the epipelagic zone, the taxonomic composition varied strongly by season; however, there was also a difference between Arctic and Atlantic water masses in winter. The spring and summer epipelagic communities were characterized by a few dominating ASVs present in low proportions during winter and in mesopelagic summer samples, suggesting that they proliferate under certain conditions, e.g., when specific hosts are abundant. Mesopelagic samples were more similar across months, and may harbor parasites of deep-dwelling organisms, little affected by season.

• Gochev, Camelia Shopen; Demory, David; Santos, Adriana Lopes dos; Carlson, Michael C. G.; Gutiérrez-Rodríguez, Andrés & Weitz, Joshua S. [Show all 7 contributors for this article] (2025). Cold Surface Waters of the Sub-Antarctic Pacific Ocean Support High Cyanophage Abundances and Infection Levels. Environmental Microbiology. ISSN 1462-2912. 27(1). doi: 10.1111/1462-2920.70031. Full text in Research Archive Show summary

  Cyanobacterial distributions are shaped by abiotic factors including temperature, light and nutrient availability as well as biotic factors such as grazing and viral infection. In this study, we investigated the abundances of T4-like and T7-like cyanophages and the extent of picocyanobacterial infection in the cold, high-nutrient-low-chlorophyll, sub-Antarctic waters of the southwest Pacific Ocean during austral spring. Synechococcus was the dominant picocyanobacterium, ranging from 4.7 × 103 to 1.2 × 105 cells∙mL−1, while Prochlorococcus abundances were relatively low overall, ranging from 1.0 × 103 to 3.9 × 104 cells∙mL−1. Using taxon-specific, single-virus and single-cell polony methods, we found that cyanophages were on average 15-fold, and up to 50-fold, more abundant than cyanobacteria in these waters. T4-like cyanophages (ranging from 1.7 × 105 to 6.5 × 105 phage·mL−1) were 2.7-fold more abundant than T7-like cyanophages (ranging from 3.1 × 104 to 2.8 × 105 phage·mL−1). Picocyanobacteria were primarily infected by T4-like cyanophages with more Synechococcus (4.8%–12.1%) infected than Prochlorococcus (2.5%–6.2%), whereas T7-like cyanophages infected less than 1% of both genera. These infection levels translated to daily mortality in the range of 5.7%–26.2% and 2.9%–14.3% of the standing stock of Synechococcus and Prochlorococcus, respectively. Our findings suggest that T4-like cyanophages are significant agents of cyanobacterial mortality in the cold, low-iron, sub-Antarctic waters of the South Pacific Ocean.

• Stige, Leif Christian; Fall, Johanna Jennifer Elisabeth & Langangen, Øystein Ole Gahr (2025). The Roles of Environmental Change and Fishing in Norwegian Coastal Cod Stock Dynamics. Fisheries Oceanography. ISSN 1054-6006. 34(4). doi: 10.1111/fog.12728. Full text in Research Archive Show summary

  Disentangling the roles of fishing and environmental factors in fish stock dynamics is fundamental for sustainable fisheries management. The stock biomass of Norwegian coastal cod north of 67°N has varied between periods of increase and decline in recent decades, with declining biomass since 2014. Here we developed a population model for the dynamics of this stock. The model was statistically fitted to survey indices of abundance- and length-at-age and environmental covariates from 1995 to 2022. The final model included a negative effect of saithe biomass on survival to age 1, positive temperature effects on growth to ages 2 and 3, density dependence in survival and growth, size-dependent maturation, and negative fishery effects on adult survival. Hindcast scenario simulations, where environmental influences or mortality from fishing were fixed, were used to disentangle the roles of recruitment, growth and adult survival for stock fluctuations in recent decades. The changes in stock biomass appear mainly to be driven by adult survival and hence fishing. The fishery effects on stock biomass were mostly the direct effects of biomass removal, with no indication of fishery-caused recruitment failure at the spatial scale represented by the model.

• Fon, Mathias; Chen, Anyuan; Ghesquière, Rosalie; Uhlig, Silvio; Edvardsen, Bente & Solhaug, Anita (2025). The cytotoxicity of the haptophyte Chrysochromulina leadbeateri towards the Atlantic salmon gill cell line ASG-10. Harmful Algae. ISSN 1568-9883. 142. doi: 10.1016/j.hal.2024.102797. Full text in Research Archive Show summary

  Fish-killing harmful algal blooms (HABs) threaten fisheries and aquaculture globally. In May and June 2019, the haptophyte Chrysochromulina leadbeateri formed the most devastating fish-killing algal bloom ever recorded in Northern Norway. Despite the severe impact of HABs on farmed fish, our understanding of their toxic mechanisms is limited. Here, we investigated the ichthyotoxicity of C. leadbeateri by using the gill epithelial cell line ASG-10 from Atlantic salmon. Extracts of C. leadbeateri showed potent hemolytic activity towards Atlantic salmon red blood cells, and toxicity to the ASG-10 cells with an EC50 of 3.41 × 106 algal cells mL−1 measured by the Alamar Blue viability assay. Furthermore, lower extract concentrations increased caspase-3/7 activity, suggesting induction of apoptosis, while higher concentrations of the extract showed compromised cell membrane integrity. No intracellular reactive oxygen species (ROS) induction was observed. Exposure to C. leadbeateri extracts cultured under different irradiances or with putrescine supplementation to the algal medium did not increase the toxicity. Exposure of living C. leadbeateri cells to ASG-10 did not show any cytotoxicity from imaging or barrier integrity impairment, but the activity of leaked dead-cell proteases revealed a concentration-dependent effect on the ASG-10 cells. Furthermore, incubation of C. leadbeateri in culture with putrescine for 72 h resulted in increased dead-cell proteases leaked from the ASG-10 cells compared to cultures without putrescine. Our findings suggest that living C. leadbeateri cells exert sublethal effects on Atlantic salmon gill cells. Additionally, putrescine seems to increase the ichthyotoxicity of living C. leadbeateri towards ASG-10 cells.

• Baumgartner, Chérine D.; Jourdain, Eve Marie; Bonhoeffer, Sebastian; Borgå, Katrine; Heide-Jørgensen, Mads P. & Karoliussen, Richard [Show all 13 contributors for this article] (2025). Kinship clustering within an ecologically diverse killer whale metapopulation. Heredity. ISSN 0018-067X. 134, p. 109–119. doi: 10.1038/s41437-024-00740-y. Full text in Research Archive Show summary

  Metapopulation dynamics can be shaped by foraging ecology, and thus be sensitive to shifts in prey availability. Genotyping 204 North Atlantic killer whales at 1346 loci, we investigated whether spatio-temporal population structuring is linked to prey type and distribution. Using population-based methods (reflecting evolutionary means), we report a widespread metapopulation connected across ecological groups based upon nuclear genome SNPs, yet spatial structuring based upon mitogenome haplotypes. These contrasting patterns of markers with maternal and biparental inheritance are consistent with matrilineal site fidelity and philopatry, and male-mediated gene flow among demes. Connectivity between fish-eating and ‘mixed-diet’ (eating both fish and mammal prey) killer whales, marks a deviation within a species renowned for its marked structure associated with ecology. However, relatedness estimates suggest distinct spatial clusters, and heterogeneity in recent gene flow between them. The contrasting patterns between inference of structure and inference of relatedness suggest that gene flow has been partially restricted over the past two to three generations (50–70 years). This coincides with the collapse of North Atlantic herring stocks in the late 1960s and the subsequent cessation of their seasonal connectivity. Statistically significant association between diet types and assignment of Icelandic killer whales to relatedness-based clusters indicated limited gene flow was maintained through Icelandic ‘mixed-diet’ whales when herring-mediated connectivity was diminished. Thus, conservation of dietary variation within this metapopulation is critical to ensure genetic health. Our study highlights the role of resource dynamics and foraging ecology in shaping population structure and emphasises the need for transnational management of this widespread migratory species and its prey.

• Hanh, Pham Thi; Dinh, van Khuong; Manh, Ngo Van; Tuan, Le Anh; Le, Minh-Hoang & Hich, Tran Vi (2025). Dietary vitamin E enhances the growth, and immunity of snubnose pompano Trachinotus blochii juveniles. Fisheries and Aquatic Sciences (FAS). ISSN 2234-1749. 28(2), p. 86–96. doi: 10.47853/FAS.2025.e9. Full text in Research Archive Show summary

  Vitamin E is the most powerful antioxidant which prevents unsaturated fatty acid from oxidation and protects cell structure. The effects of vitamin E on the growth, body composition and innate immune response of snubnose pompano juveniles (Trachinotus blochii) were assessed after ten weeks of feeding with dietary. Juveniles (360 individuals, mean initial weight 5.22 ± 0.28 g) were arbitrarily assigned equally into eighteen 200 L circular composite tanks and fed with one of six practical diets containing six levels of 2.31 (basal diet); 117.25; 189.03; 382.1; 758.54; 1,437.32 mg α-tocopherol acetate/kg. The results showed that final weight, weight gain, specific growth rate, protein efficiency ratio, hepatosomatic index, viscerosomatic index, ash, protein, lipid, hemoglobin (Hb), hematocrit (Hct), white blood cell count (WBCs) and lysozyme activity in fish fed with vitamin E supplement were considerably higher than those fed the vitamin E-free diet. Besides, feed conversion ratio and moisture in fish fed the basal diet were also higher than those fed the supplemented vitamin E diet. However, survival and red blood cell counts did not statistically differ among the experimental treatments. The results suggest that the suitable dietary vitamin E level for growth, composition and Hb, %Hct of this species were 117.25–189.03 mg/kg vitamin E supplementation, while dietary vitamin E concentration 382.1 mg/kg could be required to increase lysozyme activity and WBC numbers.

• Hyvärinen, Olli Petteri; Beest, Mariska te; Roux, Elizabeth le; Kerley, Graham I H; Buitenwerf, Robert & Druce, Dave J [Show all 10 contributors for this article] (2025). Megagrazer loss drives complex landscape-scale biophysical cascades. Environmental Research Letters. 20(2). doi: 10.1088/1748-9326/ada16e. Full text in Research Archive Show summary

  Wild animals can modulate ecosystem-climate feedbacks, e.g. through impacts on vegetation and associated carbon dynamics. However, vegetation cover and composition also affect land surface albedo, which is an important component of the global energy budget. We currently know very little about the influence of wild animals on land surface albedo and the resulting climate forcing of these albedo changes. Leveraging a unique, ecosystem-scale, semi-experimental approach, we study how the local removals of the world’s largest, terrestrial grazer, white rhinoceros (Ceratotherium simum), affected the coupling between fire dynamics, woody encroachment and surface albedo in Hluhluwe–iMfolozi Park (HiP), South Africa. Our path analysis revealed that areas in the park where more rhinos had been removed showed a stronger increase in burnt area and woody encroachment compared to areas with fewer rhinos removed, which were both related to a decrease in surface albedo. Increasing burnt area was further associated with higher rates of woody encroachment, indirectly reinforcing the negative effect of rhino loss on albedo. Our study demonstrates that removals of megagrazers in HiP were related to complex ecosystem-wide cascades with measurable impacts on land cover and surface albedo and consequences on climate forcing. This highlights the importance of restoring functional ecosystems by reinstating trophic processes.

• Le, Minh Hoang; Ngo, Manh Van; Dinh, van Khuong & Lim, Han-Kyu (2025). Effects of environmental factors on the activity of chilled storage and cryopreservation of striped Jewfish Stereolepis deoderleini sperm. Regional Studies in Marine Science. 81, p. 1–10. doi: 10.1016/j.rsma.2024.104006. Full text in Research Archive
• Beyer, Jonny; Ellingsen, Kari; Yoccoz, Nigel; Buhl-Mortensen, Pål & Bakke, Torgeir Heggelund (2025). Environmental effects monitoring of offshore oil and gas activities on the Norwegian continental shelf: A review. Marine Environmental Research. ISSN 0141-1136. 209. doi: 10.1016/j.marenvres.2025.107166. Full text in Research Archive Show summary

  This review examines the evolution and findings of Norway's offshore environmental monitoring (OEM) program over the past five decades. The program targets soft sediments, water column organisms, and deep-water epifauna across the Norwegian Continental Shelf (NCS) to assess the impacts of offshore oil and gas activities. The program is required by Norwegian authorities and financed by oil and gas companies operating on the NCS. Initially prompted by widespread effects from oil-contaminated drill cuttings (OBM-DC) discharges, the first sediment quality monitoring came in 1973, and grew into a regional sediment quality monitoring program in 1995. A ban on discharge of OBM cuttings on the NCS was implemented in 1993, and the following years saw a clear reduction in areas with impacted sediments. Currently, significant contamination and macrofauna disturbances are typically confined within 250–500 m of DC discharge points. In the 1990s, concerns over increasing produced water (PW) discharges led to development of effect monitoring in the water column, with focus on fish and mussels as bioindicators. These in situ effect surveys have shown localized impacts near PW outlets. Other fish surveys have revealed elevated DNA adduct levels in demersal fish (haddock) in several areas on the NCS, but the causality of this phenomenon remains unclear. Deep-water petroleum exploration has necessitated visual surveys to map protected benthic epifauna communities, such as corals and sponges, though the methodology's suitability for assessing biological impact is uncertain. Future recommendations include redesigning sediment surveys to address combined stressors from the petroleum industry, fisheries, and climate change, adopting recent methodological and statistical advancements, and improving integration across program elements. This review describes how the offshore monitoring on the NCS has evolved in response to changing environmental concerns, regulations and industrial practices, providing insights for enhancing ecological protection in offshore petroleum activities.

• Barrantes-Jiménez, Kenia; Lejzerowicz, Franck; Tran, Tam; Calderón-Osorno, Melany; Rivera-Montero, Luis & Rodríguez-Sánchez, César [Show all 11 contributors for this article] (2025). Anthropogenic imprint on riverine plasmidome diversity and proliferation of antibiotic resistance genes following pollution and urbanization. Water Research. ISSN 0043-1354. 281. doi: 10.1016/j.watres.2025.123553. Full text in Research Archive Show summary

  Plasmids are key determinants in microbial ecology and evolution, facilitating the dissemination of adaptive traits and antibiotic resistance genes (ARGs). Although the molecular mechanisms governing plasmid replication, maintenance, and transfer have been extensively studied, the specific impacts of urbanization-induced pollution on plasmid ecology, diversity, and associated ARGs in tropical regions remain underexplored. This study investigates these dynamics in a tropical aquatic ecosystem, providing novel insights into how pollution shapes plasmid composition and function. In contrast to the observed decrease in chromosomal diversity, we demonstrate that pollution associated with urbanization increases the diversity and taxonomic composition of plasmids within a bacterial community (plasmidome). We analyzed eighteen water and sediment metagenomes, capturing a gradient of pollution and ARG contamination along a tropical urban river. Plasmid and chromosomal diversity profiles were found to be anti-correlated. Plasmid species enrichment along the pollution gradient led to significant compositional differences in water samples, where differentially abundant species suggest plasmid maintenance within specific taxonomic classes. Additionally, the diversity and abundance of ARGs related to the plasmidome increased concomitantly with the intensity of fecal and chemical pollution. These findings highlight the critical need for targeted plasmidome studies to better understand plasmids' environmental spread, as their dynamics are independent of chromosomal patterns. This research is crucial for understanding the consequences of bacterial evolution, particularly in the context of environmental and public health.

• Bergman, Åke; Jörundsdóttir, Hrönn; Knudsen, Lisbeth E.; Viluksela, Matti; Alexander, Jan & Krøkje, Aase [Show all 17 contributors for this article] (2025). Chemical risk analysis competence in the Nordics is at stake. Environmental Science and Pollution Research. ISSN 0944-1344. doi: 10.1007/s11356-025-36318-2. Full text in Research Archive
• Calderón-Osorno, Melany; Rojas-Villalta, Dorian; Lejzerowicz, Franck Laurent Patrick; Cortés, Jorge; Arias-Andres, Maria & Rojas-Jimenez, Keilor (2025). The influence of depth on the global deep-sea plasmidome. Scientific Reports. 15(1). doi: 10.1038/s41598-025-86098-5. Full text in Research Archive Show summary

  Plasmids play a crucial role in facilitating genetic exchange and enhancing the adaptability of microbial communities. Despite their importance, environmental plasmids remain understudied, particularly those in fragile and underexplored ecosystems such as the deep-sea. In this paper we implemented a bioinformatics pipeline to study the composition, diversity, and functional attributes of plasmid communities (plasmidome) in 81 deep-sea metagenomes from the Tara and Malaspina expeditions, sampled from the Pacific, Atlantic, and Indian Oceans at depths ranging from 270 to 4005 m. We observed an association between depth and plasmid traits, with the 270–1000 m range (mesopelagic samples) exhibiting the highest number of plasmids and the largest plasmid sizes. Plasmids of Alphaproteobacteria and Gammaproteobacteria were predominant across the oceans, particularly in this depth range, which also showed the highest species diversity and abundance of metabolic pathways, including aromatic compound degradation. Surprisingly, relatively few antibiotic resistance genes were found in the deep-sea ecosystem, with most being found in the mesopelagic layer. These included classes such as beta-lactamase, biocide resistance, and aminoglycosides. Our study also identified the MOBP and MOBQ relaxase families as prevalent across various taxonomic classes. This research underscores the importance of studying the plasmidome independently from the chromosomal context. Our limited understanding of the deep-sea’s microbial ecology, especially its plasmidome, necessitates caution in human activities like mining. Such activities could have unforeseen impacts on this largely unexplored ecosystem.

• Carlsen, Eira Catharine Lødrup; Wei, Jing; Lejzerowicz, Franck; Kjær, Sigrid Trier; Westermann, Sebastian & Hessen, Dag Olav [Show all 8 contributors for this article] (2025). Redox determines greenhouse gas production kinetics and metabolic traits in water-saturated thawing permafrost peat. ISME Communications. 5(1). doi: 10.1093/ismeco/ycaf009. Full text in Research Archive Show summary

  Redox conditions, influenced by the availability of oxygen, are expected to dictate the rate of CO2 and CH4 production and to shape the composition and metabolism of microbial communities. Here, we use thawing permafrost peat in thermokarst water under a gradient of initial O2 concentrations to experimentally cover the variability in redox conditions potentially found across thawing landscapes. The three main greenhouse gases, CO2, CH4 and N2O, responded differently to O2 absence. CO2 production along the O2 gradient could be modeled by the Michaelis Menten equation revealing a sharp decrease when oxygen dropped under 100 μM. Under anoxic conditions CO2 yield decreased by 98% and maximum net production rate by 85% when compared to oxic conditions during the 11 days after thaw. N2O production was observed under anoxic conditions, while CH4 yield and CH4 accumulation rates did not differ across the redox gradient. The latter is due to the release of stored CH4 due to thawing. Differences between oxic and anoxic conditions were reflected in the microbial genomic composition, with changes in taxonomic and functional groups, such as N2O reducers, fermenters, denitrifiers and sulfur reducers increasing under anoxic conditions. Genomic changes towards less efficient central metabolism further explained the CO2 production yields and rates limited by O2 availability as predicted by thermodynamics. Together with the Michaelis Menten models the metabolic reconstruction pinpoint to critical thresholds of CO2 release at suboxic conditions and thus need to be considered when explaining and modeling highly variable CO2 emissions across thawing landscapes.

• Xiong, Ling; Aldahan, Ala; He, Peng; Lu, Xiang; Ji, Yuan & Yi, Peng [Show all 8 contributors for this article] (2025). Impact of water diversion practices on spatiotemporal changes in hydrologic and hydrochemical landscapes of surface and groundwater. CATENA. ISSN 0341-8162. 249. doi: 10.1016/j.catena.2024.108661. Full text in Research Archive
• Rao-Skirbekk, Shilpa; Gutzkow, Kristine Bjerve; Hyllestad, Susanne; Jore, Solveig; Thomsen, Cathrine & Andersen, Gro Dehli [Show all 16 contributors for this article] (2025). Climate change and health in the Arctic. Scandinavian Journal of Public Health. ISSN 1403-4948. 53(2), p. 207–214. doi: 10.1177/14034948241296309. Full text in Research Archive
• Reglero, Patricia; Tugores, Maria Pilar; Titelman, Josefin; Santandreu, Mar; Martin, Melissa & Balbin, Rosa [Show all 11 contributors for this article] (2025). Bluefin tuna (Thunnus thynnus) larvae exploit rare food sources to break food limitations in their warm oligotrophic environment. Journal of Plankton Research. ISSN 0142-7873. 47(2). doi: 10.1093/plankt/fbaf006. Full text in Research Archive Show summary

  Tuna spawns in some of the warmest and most oligotrophic areas worldwide. At the same time, starvation is often considered the main source of mortality for fish larvae. Here we assess if plankton availability is sufficient to sustain the high growth potential of tuna (Thunnus thynnus) larvae in a major spawning ground in the warm oligotrophic Mediterranean Sea. We combine field data with a model of larval foraging, growth, and bioenergetics and find that just enough food is available in the warm surface layer to sustain the high growth rate of the larvae. For bluefin tuna, higher temperatures can be beneficial if prey abundance is high, 10 000–27 000 nauplii m−3, 14–36 cladocerans m−3, 3–7 copepods m−3, but critical if not. While nauplii alone may not sustain the growth potential of even the smallest tuna larvae, our model predicts that including some larger copepods or cladocerans in the diet reduces food limitation and can sustain growth even in the warmest years. The combination of clear Mediterranean waters and the occasional copepod or cladocerans alleviates food limitation despite the low zooplankton concentrations in the area. In conclusion, oligotrophic spawning areas allow for fast growth of these foraging efficient larvae, unless temperatures exceed 28°C.

• Kroglund, Ingvild Buran; Ciesielski, Tomasz Maciej; Østnes, Jan Eivind; Patten, Michael A.; Borgå, Katrine & Jaspers, Veerle Leontina B (2025). Trace, macro and rare earth elements in a sedentary avian predator: Relationships with age and dietary tracers. Environmental Research. ISSN 0013-9351. 275, p. 1–15. doi: 10.1016/j.envres.2025.121381. Full text in Research Archive Show summary

  The tawny owl (Strix aluco) has been proposed as a key species for pan-European monitoring of pollutants because of its long lifespan and sedentary behavior. We investigated the occurrence of a wide range of essential and non-essential elements in tawny owls from central Norway and compared elemental concentration between adults and nestlings and to dietary tracers (δ13C and δ15N). Concentrations of 61 elements were analyzed using whole blood and body feathers collected from adult females (n = 52) and their nestlings (n = 61). Most detected elements were present in higher concentrations in adult feathers or blood compared to nestling feathers or blood. Mean mercury (Hg) blood concentration in adults (0.069 µg/g) exceeded the mean threshold detrimental to health (0.03 µg/g), but no molar Hg:Se ratio exceeded 1:1, so selenium (Se) is in excess in all matrices to protect against adverse effects of Hg. Cadmium (Cd) exceeded sublethal concentrations associated with oxidative stress (0.0005 µg/g) in both adult (0.0006 µg/g) and nestling (0.0010 µg/g) blood, but levels did not exceed concentrations associated with adverse health effects. Cerium (Ce), neodymium (Nd), and yttrium (Y) were detected at the highest mean concentrations of rare earth elements (REEs) in all matrices. Values of δ15N indicated that adults (7.6 ± 0.9‰) fed at lower trophic levels and with a narrower dietary niche during feather growth than did nestlings (9.0 ± 1.8‰), a finding perhaps related to nestlings consuming a higher proportion of migratory passerines. We found no relationship between relative trophic position (δ15N) or dietary carbon source (δ13C) and elemental concentrations in adults. However, δ15N data indicated biomagnification of several of the elements in nestlings, many of which were REEs. This emphasizes the need for further investigation of the biomagnification potential of REEs and their potential source, such as migrating birds.

• Fon, Mathias; Supraha, Luka; Andersen, Tom; Uhlig, Silvio & Edvardsen, Bente (2024). Optimal growth conditions of the haptophyte Chrysochromulina leadbeateri causing massive fish mortality in Northern Norway. Harmful Algae. ISSN 1568-9883. 139. doi: 10.1016/j.hal.2024.102709. Full text in Research Archive Show summary

  The haptophyte Chrysochromulina leadbeateri formed the most devastating fish-killing algal bloom ever recorded in Norway, in May and June 2019. The bloom resulted in the death of 14,500 tons of farmed salmon in Nordland and Troms Counties and large economic losses to the aquaculture industry in the region. Fish mortalities due to blooms of this species have occurred before in this region in 1991. Environmental conditions promoting bloom formation and growth of C. leadbeateri are, however, still poorly understood. Here we investigated growth as a function of temperature, salinity and irradiance in combinations using a high throughput experimental set-up. Three strains of C. leadbeateri isolated from the 2019 event and an earlier bloom in 1991 were examined. The highest maximal specific growth rate was found at salinities 28–30 and temperatures between 13 and 15 °C, with growth rate generally increasing with irradiance. The upper temperature tolerance for growth for all strains was at 17–19 °C. Further, analyses of the geographical distribution of C. leadbeateri in previous DNA-based studies compiled in the metaPR2 database revealed several ribotypes, and that a cold-water ribotype of C. leadbeateri caused both the 1991 and 2019 blooms.

• Carvalho, Cintia Oliveira; Gromstad, William Esbjug; Dunthorn, Micah; Karlsen, Hans Erik; Schrøder-Nielsen, Audun & Ready, Jonathan Stuart [Show all 10 contributors for this article] (2024). Harnessing eDNA metabarcoding to investigate fish community composition and its seasonal changes in the Oslo fjord. Scientific Reports. 14(1). doi: 10.1038/s41598-024-60762-8. Full text in Research Archive Show summary

  In the face of global ecosystem changes driven by anthropogenic activities, effective biomonitoring strategies are crucial for mitigating impacts on vulnerable aquatic habitats. Time series analysis underscores a great significance in understanding the dynamic nature of marine ecosystems, especially amidst climate change disrupting established seasonal patterns. Focusing on Norway's Oslo fjord, our research utilises eDNA-based monitoring for temporal analysis of aquatic biodiversity during a one year period, with bi-monthly sampling along a transect. To increase the robustness of the study, a taxonomic assignment comparing BLAST+ and SINTAX approaches was done. Utilising MiFish and Elas02 primer sets, our study detected 63 unique fish species, including several commercially important species. Our findings reveal a substantial increase in read abundance during specific migratory cycles, highlighting the efficacy of eDNA metabarcoding for fish composition characterization. Seasonal dynamics for certain species exhibit clear patterns, emphasising the method's utility in unravelling ecological complexities. eDNA metabarcoding emerges as a cost-effective tool with considerable potential for fish community monitoring for conservation purposes in dynamic marine environments like the Oslo fjord, contributing valuable insights for informed management strategies.

• Durant, Joël; Dupont, Nicolas; Ono, Kotaro & Langangen, Øystein Ole Gahr (2024). Interaction between three key species in the sea ice-reduced Arctic Barents Sea system. Proceedings of the Royal Society of London. Biological Sciences. ISSN 0962-8452. 291(2032). doi: 10.1098/rspb.2024.1408. Full text in Research Archive Show summary

  Population dynamics depend on trophic interactions that are affected by climate change. The rise in sea temperature is associated with the disappearance of sea ice in the Arctic. In the Arctic part of the Barents Sea, Atlantic cod, capelin and polar cod are three fish populations that interact and are confronted with climate-induced sea ice reductions. The first is a major predator in the system, while the last two are key species in Arctic and sub-Arctic ecosystems, respectively. There are still many unknowns regarding how predicted environmental change may influence the joint dynamics of these populations. Using time series from a 32 yearlong survey, we developed a state-space model that jointly modelled the dynamics of cod, capelin and polar cod. Using a hindcast scenario approach, we projected the effect of reduced sea ice on these populations. We show that the impact of sea ice reduction and concomitant sea temperature increase may lead to a decrease of polar cod abundance at the benefit of capelin but n

• Ribeiro, Catherine Gérikas; Santos, Adriana Lopes dos; Trefault, Nicole; Marie, Dominique; Lovejoy, Connie & Vaulot, Daniel (2024). Arctic phytoplankton microdiversity across the marginal ice zone: Subspecies vulnerability to sea-ice loss. Elementa: Science of the Anthropocene. 12(1), p. 1–26. doi: 10.1525/elementa.2023.00109. Full text in Research Archive Show summary

  Seasonal phytoplankton blooms are important Arctic phenomena, contributing to global primary production and biogeochemical cycling. The decline in sea-ice extent and thickness favors a longer open-water period with impacts on phytoplankton dynamics. Arctic net productivity is influenced by microalgae living associated with sea ice, with distinct species thought to be favored by ice-covered and ice-free waters. In this study, we investigated the phytoplankton community structure in Baffin Bay, a semi-enclosed sea where Arctic and North Atlantic water masses interact. We compared communities from the ice-free Atlantic-influenced eastern, the marginal ice zone, and the ice-covered Arctic-influenced western Baffin Bay. The community was characterized using 18S rRNA high-throughput amplicon sequencing and flow cytometry cell counting, and compared to environmental data collected during the Green Edge campaign. We sampled 16 stations grouped by sectors according to sea-ice cover. In the sectors associated with sea ice, phytoplankton formed a highly diverse community of smaller taxa, which contrasted with a low-diversity community in ice-free sectors, dominated by larger centric diatoms and Phaeocystis pouchetii adapted to high light/low nutrient conditions. Several phytoplankton species were flagged as indicators for the under-ice and marginal ice zone sectors, including ice-associated taxa such as the diatoms Melosira arctica and Pseudo-nitzschia seriata, but also subspecies representatives of the early-blooming alga Micromonas polaris and the cryptophyte Baffinella frigidus. The strong association of certain taxa with under-ice and marginal ice zone sectors, including Pterosperma sp., Chrysochromulina sp., Micromonas polaris, and B. frigidus, suggest that they might be indicators of diversity loss due to ongoing sea-ice changes in Baffin Bay. We report new intra-species variability of Micromonas polaris suggesting that seasonal specialists could wax and wane over the bloom and non-bloom periods, highlighting the need for detailed year-long studies and the importance of microdiversity when assessing the diversity and distribution of polar phytoplankton.

• Heuschele, Jan David; Dinh, van Khuong; Lode, Torben; Jager, Tjalling & Borgå, Katrine (2024). Arctic copepod copper sensitivity and comparison with Antarctic and temperate copepods. Ecotoxicology. ISSN 0963-9292. 33, p. 1026–1038. doi: 10.1007/s10646-024-02796-2. Full text in Research Archive Show summary

  The ongoing global climate crisis increases temperatures in polar regions faster and with greater magnitude than elsewhere. The decline of Arctic sea ice opens up new passages, eventually leading to higher anthropogenic activities such as shipping, fishing, and mining. Climate change and anthropogenic activities will increase contaminant transport from temperate to Arctic regions. The shipping industry uses copper as an antifouling coating. Copper is an essential element but becomes toxic at excess concentrations, and its use may inadvertently affect non-target organisms such as copepods. Copper affects copepods by lowering reproductive output, prolonging developmental time, and causing increased mortality. As data on copper sensitivity of polar copepods at low temperatures are rare, we conducted onboard survival experiments with the Arctic region’s most common copepod species (Calanus finmarchicus, C. glacialis, C. hyperboreus). Acute survival tests were done for up to 8 days on individuals in 70 ml bottles at 1 °C with nominal copper concentrations ranging from 3 to 480 μg L−1. We used a reduced General Unified Threshold model for Survival (GUTS) to analyse the data, and placed our results in the context of the few published copper sensitivity data of the Antarctic and temperate copepod species at low temperatures. The sensitivity of Cu exposure was similar between the three Calanus species. However, a model comparison suggests that the tested C. glacialis population is less sensitive than the other two species in our experiments. Compared to published data, the three Arctic species appear slightly less sensitive to copper compared to their Antarctic counterparts but more compared to their temperate ones. Our literature search revealed only a few available studies on the copper sensitivity of polar copepods. In the future, this species group will be exposed to more pollutants, which warrants more studies to predict potential risks, especially given possible interactions with environmental factors.

• Carlsen, Eira Catharine Lødrup; Hjelset, Sverre; Gomes, Tania; Igartua, Amaia; Sørensen, Lisbet & Booth, Andy [Show all 8 contributors for this article] (2024). Synthetic and natural rubber associated chemicals drive functional and structural changes as well as adaptations to antibiotics in in vitro marine microbiomes. Ecotoxicology and Environmental Safety. ISSN 0147-6513. 273. doi: 10.1016/j.ecoenv.2024.116134. Full text in Research Archive Show summary

  The leaching of additives from plastics and elastomers (rubbers) has raised concerns due to their potential negative impacts on the environment and the development of antibiotic resistance. In this study, we investigated the effects of chemicals extracted from two types of rubber on microbiomes derived from a benthic sea urchin and two pelagic fish species. Additionally, we examined whether bacterial communities preconditioned with rubber-associated chemicals displayed adaptations to antibiotics. At the highest tested concentrations of chemicals, we observed reduced maximum growth rates and yields, prolonged lag phases, and increased alpha diversity. While the effects on alpha and beta diversity were not always conclusive, several bacterial genera were significantly influenced by chemicals from the two rubber sources. Subsequent exposure of sea urchin microbiomes preconditioned with rubber chemicals to the antibiotic ciprofloxacin resulted in decreased maximum growth rates. This indicates a more sensitive microbiome to ciprofloxacin when preconditioned with rubber chemicals. Although no significant interaction effects between rubber chemicals and ciprofloxacin exposure were observed in bacterial alpha and beta diversity, we observed log-fold changes in two bacterial genera in response to ciprofloxacin exposure. These findings highlight the structural and functional alterations in microbiomes originating from various marine species when exposed to rubber-associated chemicals and underscore the potential risks posed to marine life.

• Olsen, Tora; Stige, Leif Christian; Dupont, Nicolas; Durant, Joël & Langangen, Øystein Ole Gahr (2024). Repeated large declines in the Barents Sea capelin population are associated with different ecosystem conditions. ICES Journal of Marine Science. ISSN 1054-3139. 81(8), p. 1584–1593. doi: 10.1093/icesjms/fsae101. Full text in Research Archive Show summary

  Although fluctuations in the biomass of small pelagic fish are strong and rapid, they are largely investigated as individual events or generalized to what is common across several species and populations. The Barents Sea capelin population, which experienced four large decreases in biomass between 1980 and 2016, can be used to compare the similarity of causes and sequence of events leading up to large biomass decline in the same population. Here, we used an age-structured state-space model to investigate the possible contributions from somatic growth, food availability, temperature, predation by Atlantic cod, herring interactions, and/or fisheries on the capelin biomass declines. We recalculated total biomass while perturbing these effects and assessed the change in total biomass. We did not find a single, common cause for the dramatic biomass declines. Although median biomass increased in several of the scenarios, a large decline in total biomass was mostly retained. Atlantic cod predation and food availability influenced adult capelin biomass. Food availability mainly impacted the first period, while the importance of Atlantic cod predation increased from the first period to the third period. Reducing larval mortality from herring interactions or temperature did not suppress the biomass declines. Recruitment failures were maintained due to a combination of process errors and uncertainty in the effect of spawning biomass, and thus fisheries, on age 0 abundance. The impact of each perturbation depended on the specific ecosystem context at the time of the biomass decline.

• Olsen, Tora; Frøysa, Håvard Guldbrandsen; Yaragina, Natalya; Titelman, Josefin; Durant, Joël & Langangen, Øystein Ole Gahr (2024). Predator biomass affects west–east shifts in Barents Sea capelin (Mallotus villosus) spawning ground use. Fisheries Oceanography. ISSN 1054-6006. 33(6). doi: 10.1111/fog.12685. Full text in Research Archive Show summary

  Spawning locations of migratory fish influence the environmental and oceanographic fate of eggs and larvae. However, we have an incomplete understanding of how and why realized spawning locations vary. We quantified the yearly variation in spawning location for Barents Sea capelin (Mallotus villosus) within the recognized spawning areas along the coast of northern Norway and Murman. Furthermore, we tested whether water temperature, sea ice cover, predation and capelin fisheries are associated with spawning locations. Estimated spatial variation in spawning longitude used data from Soviet-Russian ichthyoplankton surveys from 1959 to 1993 and a bootstrap procedure. The mean spawning area along the coast was then calculated by combining larvae observations with backtracking a larvae drift model from potential spawning areas. We fitted a generalized additive model (GAM) to assess the effects of environmental conditions on these drift-corrected spawning longitudes. Capelin's mean yearly spawning location varied substantially across the study period. An increase in immature cod biomass, a major predator of capelin, during the spawning migration period in winter and early spring corresponds to more eastward capelin spawning. The eastward shift in mean spawning longitude seems to reach an eastern limit at high immature cod biomass. Sea temperature, sea ice cover and capelin fisheries were not associated with mean capelin spawning longitude. We show that the realized spawning areas for capelin are related to cod biomass, potentially through cod predation depleting and/or acting as a migration barrier for mature capelin.

• Kristiansen, Silje Marie; Leinaas, Hans Petter; Gestel, Cornelis A.M. van & Borgå, Katrine (2024). Thermal adaptation affects the temperature-dependent toxicity of the insecticide imidacloprid to soil invertebrates. Science of the Total Environment. ISSN 0048-9697. 944. doi: 10.1016/j.scitotenv.2024.173845. Full text in Research Archive Show summary

  Terrestrial ectotherms are vulnerable to climate change since their biological rates depend on the ambient temperature. As temperature may interact with toxicant exposure, climate change may cause unpredictable responses to toxic stress. A population's thermal adaptation will impact its response to temperature change, but also to interactive effects from temperature and toxicants, but these effects are still not fully understood. Here, we assessed the combined effects of exposure to the insecticide imidacloprid across the temperatures 10–25 °C of two populations of the Collembola Hypogastrura viatica (Tullberg, 1872), by determining their responses in multiple life history traits. The con-specific populations differ considerably in thermal adaptations; one (arctic) is a temperature generalist, while the other (temperate) is a warm-adapted specialist. For both populations, the sub-lethal concentrations of imidacloprid became lethal with increasing temperature. Although the thermal maximum is higher for the warm-adapted population, the reduction in survival was stronger. Growth was reduced by imidacloprid in a temperature-dependent manner, but only at the adult life stage. The decrease in adult body size combined with the absence of an effect on the age at first reproduction suggests a selection on the timing of maturation. Egg production was reduced by imidacloprid in both populations, but the negative effect was only dependent on temperature in the warm-adapted population, with no effect at 10 °C, and decreases of 41 % at 15 °C, and 74 % at 20 °C. For several key traits, the population best adapted to utilize high temperatures was also the most sensitive to toxic stress at higher temperatures. It could be that by allocating more energy to faster growth, development, and reproduction at higher temperatures, the population had less energy for maintenance, making it more sensitive to toxic stress. Our findings demonstrate the need to take into account a population's thermal adaptation when assessing the interactive effects between temperature and other stressors.

• Huard, Jacqueline R.; Hemming, Victoria; Baker, Matthew R.; Blancard, Jennifer; Bruce, Ian & Cook, Sarah [Show all 26 contributors for this article] (2024). Threat assessment for Pacific sand lance (Ammodytes personatus) in the Salish Sea. Frontiers in Marine Science. 11. doi: 10.3389/fmars.2024.1445215. Full text in Research Archive Show summary

  Like many forage fish species, Pacific sand lance (Ammodytes personatus) play a key role in nearshore marine ecosystems as an important prey source for a diverse array of predators in the northeastern Pacific. However, the primary threats to Pacific sand lance and their habitat are poorly defined due to a lack of systematic data. Crucial information needed to assess their population status is also lacking including basic knowledge of their local and regional abundance and distribution. Sand lance are currently listed as ‘not evaluated’ under the IUCN red list and they have not been assessed by US and Canadian agencies. This hampers management and policy efforts focused on their conservation. To address this knowledge gap, we conducted a three-part, structured expert elicitation to assess the vulnerability of Salish Sea sand lance populations. Experts were asked to list and rank key threats to Salish Sea sand lance and/or their habitat, to further quantify the vulnerability of sand lance to identified threats using a vulnerability matrix, and to predict the population trajectory in 25 years from today. Impacts associated with climate change (e.g. sea level rise, sea temperature rise, ocean acidification, and extreme weather) consistently ranked high as threats of concern in the ranking exercise and quantified vulnerability scores. Nearly every expert predicted the population will have declined from current levels in 25 years. These results suggest sand lance face numerous threats and may be in decline under current conditions. This research provides vital information about which threats pose the greatest risk to the long-term health of sand lance populations and their habitat. Managers can use this information to prioritize which threats to address. Future research to reliably quantify population size, better understand the roles of natural and anthropogenic impacts, and to identify the most cost-effective actions to mitigate multiple threats, is recommended.

• Ferreira, Ana Sofia de Araújo; Langangen, Øystein Ole Gahr; Yaragina, Nathalia A.; Prokopchuk, Irina P. & Durant, Joël (2024). How the spatio-temporal overlap of cod, haddock, and capelin larvae affects their recruitment in the Norwegian–Barents Sea system. Marine Ecology Progress Series. ISSN 0171-8630. 734, p. 79–90. doi: 10.3354/meps14564. Full text in Research Archive Show summary

  The Norwegian-Barents Sea (NBS) system is very productive; however, the extent to which this productivity varies remains uncertain for many species. Cod Gadus morhua , haddock Melanogrammus aeglefinus , and capelin Mallotus villosus are 3 key species that overlap in a large portion of the NBS ecosystem. In this hypothesis-driven study, we investigated the interaction of these 3 species during their pelagic larval stage and assessed the impact of their spatio-temporal overlap on survival. We hypothesised that the spatio-temporal overlap between the larvae of the 3 species, as they likely drift together, influences their survival at later stages. We calculated the spatio-temporal overlap of each pair of the 3 studied species and tested it against their recruitment. We utilised a multiple linear regression model with temperature, spawning stock biomass, and spatio-temporal overlap among larvae, their food, and competitors as explanatory variables; this model explained ∼43, ∼24, and ∼73% of the variability in cod, haddock, and capelin recruitment, respectively. The overlaps between larval cod and competing species and/or food have a negative influence on cod recruitment, whereas the sign of the relationships pertaining to haddock and capelin varies. These results improve our understanding of how these fish species use their critical habitats to face emerging environmental stressors.

• Durant, Joël; Holt, Rebecca Emma & Langangen, Øystein Ole Gahr (2024). Large biomass reduction effect on the relative role of climate, fishing, and recruitment on fish population dynamics. Scientific Reports. 14(1). doi: 10.1038/s41598-024-59569-4. Full text in Research Archive Show summary

  Many species around the world have collapsed, yet only some have recovered. A key question is what happens to populations post collapse. Traditionally, marine fish collapses are linked to overfishing, poor climate, and recruitment. We test whether the effect on biomass change from these drivers remains the same after a collapse. We used a regression model to analyse the effect of harvesting, recruitment, and climate variability on biomass change before and after a collapse across 54 marine fish populations around the world. The most salient result was the change in fishing effect that became weaker after a collapse. The change in sea temperature and recruitment effects were more variable across systems. The strongest changes were in the pelagic habitats. The resultant change in the sensitivity to external drivers indicates that whilst biomass may be rebuilt, the responses to variables known to affect stocks may have changed after a collapse. Our results show that a general model applied to many stocks provides useful insights, but that not all stocks respond similarly to a collapse calling for stock-specific models. Stocks respond to environmental drivers differently after a collapse, so caution is needed when using pre-collapse knowledge to advise on population dynamics and management.

• Wang, Xinhui; Fon, Mathias; Andersen, Aaron John Christian; Solhaug, Anita; Ingebrigtsen, Richard Andre & Samdal, Ingunn Anita [Show all 10 contributors for this article] (2024). Insights into the nature of ichthyotoxins from the Chrysochromulina leadbeateri blooms in Northern Norwegian fjords. Harmful Algae. ISSN 1568-9883. 137. doi: 10.1016/j.hal.2024.102681. Full text in Research Archive Show summary

  In May–June 2019, the microalga Chrysochromulina leadbeateri caused a massive fish-killing event in several fjords in Northern Norway, resulting in the largest direct impact ever on aquaculture in northern Europe due to toxic algae. Motivated by the fact that no algal toxins have previously been described from C. leadbeateri, we set out to investigate the chemical nature and toxicity of secondary metabolites in extracts of two strains (UIO 393, UIO 394) isolated from the 2019 bloom, as well as one older strain (UIO 035) isolated during a bloom in Northern Norway in 1991. Initial LC–DAD–MS/MS-based molecular networking analysis of the crude MeOH extracts of the cultivated strains showed that their profiles of small organic molecules, including a large number of known lipids, were very similar, suggesting that the same class of toxin(s) were likely the causative agents of the two harmful algal bloom (HAB) events. Next, bioassay-guided fractionation using the RTgill-W1 cell line and metabolomics analysis pointed to a major compound affording [M + H]+ ions at m/z 1399.8333 as a possible toxin, corresponding to a compound with the formula C67H127ClO27. Moreover, our study unveiled a series of minor analogues exhibiting distinct patterns of chlorination and sulfation, together defining a new family of compounds, which we propose to name leadbeaterins. Remarkably, these suspected toxins were detected in situ in samples collected during the 2019 bloom close to Tromsø, thereby consistent with a role in fish kills. The elemental compositions of the putative C. leadbeateri ichthyotoxins strongly indicate them to be long linear polyhydroxylated polyketides, structurally similar to sterolysins reported from a number of dinoflagellates.

• Garvang, Even Sletteng; Eliassen, Lasse Krøger; Titelman, Josefin & Andersen, Tom (2024). Outbreak conditions and impacts of parasites in copepod populations. Ecosphere. 15(12), p. 1–18. doi: 10.1002/ecs2.70093. Full text in Research Archive
• Abe, Keita; Diekert, Florian Klaus; Melsom, Arne & Langangen, Øystein Ole Gahr (2024). Do fishers follow fish displaced by climate warming? npj Ocean Sustainability. 3(1), p. 1–7. doi: 10.1038/s44183-024-00063-9. Full text in Research Archive Show summary

  Climate change is associated with altered oceanographic conditions that tend to shift the geographical distributions of fish. To assess the impact of climate change on fisheries, one must go beyond projections of catch potential and understand how fishers respond to moving target species. Many previous studies have explicitly or implicitly assumed that fishers follow fish that are displaced by climate warming. Here, we evaluate this assumption by analyzing a long-term, large-scale yet high-resolution dataset combined with a detailed oceanographic model. Our study case is the Atlantic cod (Gadhus morhua) fishery in Norway, one of the largest whitefish fisheries in the world, with little technological or judicial constraints on the potential spatial response of fishers. An oceanographic model is used to predict the areas that have been suitable for Atlantic cod spawning over the two last decades. We compare whether these areas overlap with actually observed fishing locations. While the areas that are suitable for spawning clearly predict how much fish are caught per trip, the suitability of an area does not predict how many vessels fish in a given area at a given point in time. In contrast, the number of vessels in the previous week and the previous year explain the current number of vessels in that area. Hence, future projections of climate change effects should account for the rich and nuanced behavioral responses of humans to project climate change effects on fisheries.

• Volpe, Charlotte; Nymark, Marianne; Andersen, Tom; Winge, Per; Lavaud, Johann & Vadstein, Olav (2024). Skeletonema marinoi ecotypes show specific habitat-related responses to fluctuating light supporting high potential for growth under photobioreactor light regime. New Phytologist. ISSN 0028-646X. 243(1), p. 145–161. doi: 10.1111/nph.19788. Full text in Research Archive Show summary

  * Diatoms are a diverse group of phytoplankton usually dominating areas characterized by rapidly shifting light conditions. Because of their high growth rates and interesting biochemical profile, their biomass is considered for various commercial applications. This study aimed at identifying strains with superior growth in a photobioreactor (PBR) by screening the natural intraspecific diversity of ecotypes isolated from different habitats. We investigated the effect of PBR light fluctuating on a millisecond scale (FL, simulating the light in a PBR) on 19 ecotypes of the diatom Skeletonema marinoi isolated from the North Sea–Baltic Sea area. * We compare growth, pigment ratios, phylogeny, photo-physiological variables and photoacclimation strategies between all strains and perform qPCR and absorption spectra analysis on a subset of strains. * Our results show that the ecotypes responded differently to FL, and have contrasting photo-physiological and photoprotective strategies. The strains from Kattegat performed better in FL, and shared common photoacclimation and photoprotection strategies that are the results of adaptation to the specific light climate of the Kattegat area. * The strains that performed better with FL conditions had a high light (HL)-acclimated phenotype coupled with unique nonphotochemical quenching features. Based on their characteristics, three strains were identified as good candidates for growth in PBRs.

• Trégarot, Ewan; D'Olivo, Juan Pablo; Botelho, Andrea Zita; Cabrito, Andrea; Cardoso, Gabriel O. & Casal, Gema [Show all 21 contributors for this article] (2024). Effects of climate change on marine coastal ecosystems – A review to guide research and management. Biological Conservation. ISSN 0006-3207. 289, p. 1–22. doi: 10.1016/j.biocon.2023.110394. Full text in Research Archive Show summary

  There is growing concern over climate models that project significant changes in the oceans, with consequences on marine biodiversity and human well-being. However, marine and coastal ecosystems respond differently to climate change-related stressors depending on the ecosystem, species composition and interactions, geomorphologic settings, and spatial distribution, but also on the presence of local stressors interacting cumulatively with climate change-related pressures. Our paper provides a comprehensive review of the current literature about the effects of climate-related pressures on marine and coastal ecosystems and how local stressors affect their resilience. Our work focuses on key marine and coastal ecosystems from three ecoregions: the Caribbean Sea (coral reefs, mangrove forests, seagrass beds), the Mediterranean Sea (the coral Cladocora caespitosa, maërl beds and seagrass beds) and the North-East Atlantic, which include kelp forests, maërl beds, salt marshes and seagrass beds. This review highlights the need for a more comprehensive, multi-species, and multi-stressors approach to predict better changes at the ecosystem and seascape levels of marine and coastal ecosystems. Nevertheless, there is enough evidence to argue that addressing locally key manageable stressors common to multiple ecosystems, such as nutrient enrichment, coastal development, hydrologic disturbances, anchoring or sedimentation, will reduce the identified adverse effects of climate change. This knowledge is critical for practical conservation actions and coastal and marine spatial management at the ecoregion scale and beyond.

• Giebichenstein, Julia; Andersen, Tom; Varpe, Øystein; Gabrielsen, Geir W. & Borgå, Katrine (2024). Little seasonal variation of mercury concentrations and biomagnification in an Arctic pelagic food web. Progress in Oceanography. ISSN 0079-6611. 231. doi: 10.1016/j.pocean.2024.103381. Full text in Research Archive Show summary

  Despite numerous studies on mercury in Arctic biota, data from inaccessible, ice-covered regions − especially during the polar night and late winter − remain scarce. This scarcity results in poor understanding of the seasonal dynamics of mercury within the food web. From the Northern Barents Sea, we quantified total mercury and the dietary descriptors δ15N and δ13C as long-term dietary signals (weeks to months) in biota to a) investigate the seasonal pelagic food web structure, b) seasonality in total mercury concentration, c) and its biomagnification in the food web. Mercury and dietary descriptors were analyzed in copepods, macrozooplankton (krill, amphipods, arrow worms and pteropods) and the fishes, Atlantic cod (Gadus morhua), polar cod (Boreogadus saida) and capelin (Mallotus villosus) during spring, late summer, early,and late winter. Seasonal changes were observed in δ15N values in some macrozooplankton and capelin, and some seasonal variation was observed across the food web with depleted δ13C values in spring and enriched δ13C values in late summer. Mercury concentrations were lower (range: 2.49 ng/g dw in the krill Thyssanossa sp. – 70.55 ng/g dw in the pelagic pteropod Clione limacina) than reported from other parts of the Arctic. We found a positive linear relationship between mercury and relative trophic position represented by δ15N, i.e., biomagnification, during all seasons, except in early winter. As Clione limacina likely had different turnover rates for mercury and stable isotopes resulting in low δ15N, but high mercury concentrations in early winter, compared to the other species in the food web, the pteropod was omitted from the regression. By omitting Clione limacina, biomagnification was similar across all seasons (R2adj = 0.45). Thus, we saw clear mercury biomagnification with consistent and little seasonal variation in this high Arctic marine food web despite large seasonal fluctuations in abiotic and biotic conditions.

• Bjørnestad, Synne Arstad; Solbakken, Monica Hongrø; Krokene, Pia; Thiede, Bernd; Hylland, Ketil & Jakobsen, Kjetill Sigurd [Show all 9 contributors for this article] (2024). The Atlantic Cod MHC I compartment has the properties needed for cross-presentation in the absence of MHC II. Scientific Reports. 14(1). doi: 10.1038/s41598-024-76225-z. Full text in Research Archive Show summary

  Atlantic cod has a peculiar immune system, characterized by the loss of Major Histocompatibility Complex (MHC) class II pathway, and an extreme expansion of the MHC class I gene repertoire. This has led to the hypothesis that some of the MHC I variants have replaced MHC II by presenting exogenous-peptides in a process similar to cross-presentation. In mammals, MHC I loads endogenous antigens in the endoplasmic reticulum, but we recently found that different Atlantic cod MHC I gene variants traffic to endolysosomes. There, they colocalize with Tapasin and other components of the peptide-loading complex, indicating a plausible peptide-loading system outside the endoplasmic reticulum. In this study, we further characterize the identity of the Atlantic cod MHC I compartment (cMIC). We found that, similarly to mammalian MHC II compartment, cMIC contains late endosomal markers such as Rab7, LAMP1 and CD63. Furthermore, we identified Hsp90b1 (also known as grp94) and LRP1 (also known as CD91) as interactors of MHC I by mass spectrometry. As these two proteins are involved in cross-presentation in mammals, this further suggests that Atlantic cod MHC I might use a similar mechanism to present exogenous peptides, thus, compensating for the absence of MHC II.

• Vu, Quyen D. H.; Pham, Linh P.; Truong, Oanh T.; Tran, Sang Q.; Bui, Canh V. & Le, Minh-Hoang [Show all 8 contributors for this article] (2024). Extreme Temperatures Reduce Copepod Performance and Change the Relative Abundance of Internal Microbiota. Ecology and Evolution. 14(10). doi: 10.1002/ece3.70408. Full text in Research Archive Show summary

  Copepods are one of the most abundant invertebrate groups in the seas and oceans and are a significant food source for marine animals. Copepods are also particularly sensitive to elevated temperatures. However, it is relatively unknown how the internal microbiome influences copepod susceptibility to warming. We addressed this fundamental knowledge gap by assessing key life history traits (survival, development, and reproduction) and changes in the internal microbiome in the tropical calanoid copepod Acartia sp. in response to warming (26°C, 30°C, and 34°C). Copepod microbiomes were analyzed using high throughput DNA sequencing of V1–V9 of 16S rRNA hypervariable regions. Copepod performance was better at 30°C than at 26°C, as indicated by faster development, a higher growth rate, and fecundity. However, these parameters strongly decreased at 34°C. We recorded 1,262,987 amplicon sequence reads, corresponding to 392 total operational taxonomic units (OTUs) at 97% similarity. Warming did not affect OTU numbers and the biodiversity indices, but it substantially changed the relative abundance of three major phyla: Proteobacteria, Actinobacteria, and Bacteroidota. The thermophilic and opportunistic Proteobacteria and Bacteroidota increased under extreme temperatures (34°C) while Actinobacteria abundance was strongly reduced. Changes in the relative abundance of these bacteria might be related to reduced copepod growth, survival, and reproduction under extreme temperatures. Profiling the functional role of all internal bacterial groups in response to the temperature change will fundamentally advance our mechanistic understanding of the performance of tropical copepods and, more generally, marine invertebrates to a warming climate.

• Tabane, Fatou; Diagne, Diabou; Niang, Doudou Georges; Cazier, Fabrice; Dewaélé, Dorothée & Lèye, Nafissatou [Show all 11 contributors for this article] (2024). Biomarkers and contaminants in the bivalve Perna perna caged in coastal sites in Senegal. International Journal of Biological and Chemical Sciences (IJBCS). ISSN 1991-8631. 18(2), p. 555–570. doi: 10.4314/ijbcs.v18i2.18. Full text in Research Archive
• Möllerke, Anton; Vidal, Diogo Montes; Leinaas, Hans Petter & Schulz, Stefan (2024). Socialane, a Nonaprenyl Terpene Hydrocarbon Surface Lipid from the Collembola Hypogastrura socialis. Chemistry - A European Journal. ISSN 0947-6539. 30(27). doi: 10.1002/chem.202400272. Full text in Research Archive Show summary

  Springtails use unique compounds for their outermost epicuticular wax layer, often of terpenoid origin. We report here the structure and synthesis of socialane, the major cuticular constituent of the Collembola Hypogastrura socialis. Socialane is also the first regular nonaprenyl terpene with a cyclic head group. The saturated side chain has seven stereogenic centers, making the determination of the configuration difficult. We describe here the identification of socialane and a synthetic approach using the building blocks farnesol and phytol, enantioselective hydrogenation, and α-alkylation of sulfones for the synthesis of various stereoisomers. NMR experiments showed the presence of an anti-configuration of the methyl groups closest to the benzene ring and that the other methyl groups of the polyprenyl side-chain are not uniformly configured. Furthermore, socialane is structurally different from [6+2]-terpene viaticene of the closely related H. viatica, showing species specificity of the epicuticular lipids of this genus and hinting at a possible role of surface lipids in the communication of these gregarious arthropods.

• Johannesen, Edda; Frøysa, Håvard Guldbrandsen; Langangen, Øystein Ole Gahr & Vikebø, Frode Bendiksen (2024). Northeast Arctic haddock (Melanogrammus aeglefinus) spawning grounds and drift to nursery areas in the Barents Sea. Fisheries Oceanography. ISSN 1054-6006. 33(6). doi: 10.1111/fog.12694. Full text in Research Archive Show summary

  The Northeast Arctic stock of haddock (Melanogrammus aeglefinus) is the most northerly stock of the species. It is one of the largest haddock stocks but not the most studied. Similar to the more extensively studied sympatric cod (Gadus morhua) and herring (Clupea harengus) stocks, it relies on Atlantic currents for egg and larvae transportation from spawning grounds to nursery areas in the Barents Sea. The exact locations of the spawning grounds have not been known and the maps that have been published differ substantially. Here, we present results from the first survey dedicated to exploring the spawning habitat of Northeast Arctic (NEA) haddock, and a particle drift and larvae growth model with physical forcing from a high-resolution ocean model. Gadoid eggs, later identified as haddock by DNA analyses, as well as spawning individuals were sampled at the survey. Spawning haddock was found in Atlantic water in temperatures 3.6–6.2°C and depths of 240–560 m. Sampled eggs were mostly in early development stages, suggesting that they were largely spawned in the surveyed area. Using the drift model, we found that most of the modelled particles released as eggs at our surveyed area ended up in the nursery area in the Barents Sea. A crude estimate of the spawning stock biomass based on the survey suggests that the most updated spawning ground map of NEA haddock might be too restricted in its extent. Particle drift and growth with physical forcing for the years 2012–2022 indicated small interannual variation in aberrant drift, and that growth driven by ambient temperature could be important in explaining interannual variation in haddock recruitment.

• Orr, James A.; Macaulay, Samuel J.; Mordente, Adriana; Burgess, Benjamin; Albini, Dania & Hunn, Julia G. [Show all 28 contributors for this article] (2024). Studying interactions among anthropogenic stressors in freshwater ecosystems: A systematic review of 2396 multiple-stressor experiments. Ecology Letters. ISSN 1461-023X. 27(6). doi: 10.1111/ele.14463. Full text in Research Archive Show summary

  Understanding the interactions among anthropogenic stressors is critical for effective conservation and management of ecosystems. Freshwater scientists have invested considerable resources in conducting factorial experiments to disentangle stressor interactions by testing their individual and combined effects. However, the diversity of stressors and systems studied has hindered previous syntheses of this body of research. To overcome this challenge, we used a novel machine learning framework to identify relevant studies from over 235,000 publications. Our synthesis resulted in a new dataset of 2396 multiple-stressor experiments in freshwater systems. By summarizing the methods used in these studies, quantifying trends in the popularity of the investigated stressors, and performing co-occurrence analysis, we produce the most comprehensive overview of this diverse field of research to date. We provide both a taxonomy grouping the 909 investigated stressors into 31 classes and an open-source and interactive version of the dataset (https://jamesaorr.shinyapps.io/freshwater-multiple-stressors/). Inspired by our results, we provide a framework to help clarify whether statistical interactions detected by factorial experiments align with stressor interactions of interest, and we outline general guidelines for the design of multiple-stressor experiments relevant to any system. We conclude by highlighting the research directions required to better understand freshwater ecosystems facing multiple stressors.

• Albini, Dania; Lutier, Mathieu; Heimböck, Martin Paul; Heuschele, Jan David; Søreide, Janne & Jackson, Michelle C. [Show all 7 contributors for this article] (2024). Temporal patterns in multiple stressors shape the vulnerability of overwintering Arctic zooplankton. Ecology and Evolution. 14(7). doi: 10.1002/ece3.11673. Full text in Research Archive Show summary

  The Arctic polar nights bring extreme environmental conditions characterised by cold and darkness, which challenge the survival of organisms in the Arctic. Additionally, multiple anthropogenic stressors can amplify the pressure on the fragile Arctic ecosystems during this period. Determining how multiple anthropogenic stressors may affect the survival of Arctic life is crucial for ecological risk assessments and management, but this topic is understudied. For the first time, our study investigates the complex interactions of multiple stressors, exploring stressor temporal dynamics and exposure duration on a key Arctic copepod Calanus glacialis during the polar nights. We conducted experiments with pulse (intermittent) and press (continuous) exposure scenarios, involving microplastics, pyrene and warming in a fully factorial design. We observed significant effects on copepod survival, with pronounced impacts during later stressor phases. We also detected two-way interactions between microplastics and pyrene, as well as pyrene and warming, further intensified with the presence of a third stressor. Continuous stressor exposure for 9 days (press-temporal scenario) led to greater reductions in copepod survival compared to the pulse-temporal scenario, characterised by two 3-day stressor exposure phases. Notably, the inclusion of recovery phases, free from stressor exposure, positively influenced copepod survival, highlighting the importance of temporal exposure dynamics. We did not find behaviour to be affected by the different treatments. Our findings underscore the intricate interactions amongst multiple stressors and their temporal patterns in shaping the vulnerability of overwintering Arctic copepods with crucial implications for managing Arctic aquatic ecosystems under the fastest rate of ongoing climate change on earth.

• Dupont, Nicolas; Durant, Joël; Langangen, Øystein Ole Gahr & Stige, Leif Christian (2024). Changes in prey-predator interactions in an Arctic food web under climate change. Progress in Oceanography. ISSN 0079-6611. 229, p. 1–16. doi: 10.1016/j.pocean.2024.103380. Full text in Research Archive Show summary

  Global warming affects marine ecosystems by changing environmental conditions, ecosystem structure, and ecosystem functioning. In parts of the Arctic, increased sea temperature and decreased sea ice have led to a poleward expansion of boreal species and increased their interactions with native Arctic species. To investigate and quantify the changing interactions in an Arctic marine food web under new environmental conditions, we studied the interactions between key prey fish species in the seasonally ice-covered parts of the Barents Sea: adult polar cod (Boreogadus saida) and capelin (Mallotus villosus) and one of the major predators in the system: Atlantic cod (Gadus morhua). For this, we compared the predictive performance of threshold models predicting the abundance of adult polar cod as a function of Atlantic cod. Each model was associated with a hypothesis describing prey-predator interactions in different environmental conditions defined by threshold values of summer sea-ice or capelin stock biomass. The best predictive model showed that the predation effect of Atlantic cod on polar cod was strongest in years of low summer sea ice cover and low capelin stock biomass. Our results exemplified that Arctic species such as polar cod may experience increased predation pressure under climate change from boreal species such as Atlantic cod. These effects depend, however, not only on changes in abiotic drivers of species distributions, but also on food-web interactions involving mid-trophic level species such as capelin.

• Andvik, Clare Margaret; Jourdain, Eve Marie; Borgen, Anders; Lyche, Jan Ludvig; Karoliussen, Richard & Haug, Tore [Show all 7 contributors for this article] (2024). Intercorrelations of Chlorinated Paraffins, Dechloranes, and Legacy Persistent Organic Pollutants in 10 Species of Marine Mammals from Norway, in Light of Dietary Niche. Environmental Science and Technology. ISSN 0013-936X. 58(33), p. 14797–14811. doi: 10.1021/acs.est.4c02625. Full text in Research Archive Show summary

  Short-, medium-, and long-chain chlorinated paraffins (CPs) (SCCPs, MCCPs, and LCCPs) and dechloranes are chemicals of emerging concern; however, little is known of their bioaccumulative potential compared to legacy contaminants in marine mammals. Here, we analyzed SCCPs, MCCPs, LCCPs, 7 dechloranes, 4 emerging brominated flame retardants, and 64 legacy contaminants, including polychlorinated biphenyls (PCBs), in the blubber of 46 individual marine mammals, representing 10 species, from Norway. Dietary niche was modeled based on stable isotopes of nitrogen and carbon in the skin/muscle to assess the contaminant accumulation in relation to diet. SCCPs and dechlorane-602 were strongly positively correlated with legacy contaminants and highest in killer (Orcinus orca) and sperm (Physeter macrocephalus) whales (median SCCPs: 160 ng/g lw; 230 ng/g lw and median dechlorane-602: 3.8 ng/g lw; 2.0 ng/g lw, respectively). In contrast, MCCPs and LCCPs were only weakly correlated to recalcitrant legacy contaminants and were highest in common minke whales (Balaenoptera acutorostrata; median MCCPs: 480 ng/g lw and LCCPs: 240 ng/g lw). The total contaminant load in all species was dominated by PCBs and legacy chlorinated pesticides (63–98%), and MCCPs dominated the total CP load (42–68%, except 11% in the long-finned pilot whale Globicephala melas). Surprisingly, we found no relation between contaminant concentrations and dietary niche, suggesting that other large species differences may be masking effects of diet such as lifespan or biotransformation and elimination capacities. CP and dechlorane concentrations were higher than in other marine mammals from the (sub)Arctic, and they were present in a killer whale neonate, indicating bioaccumulative properties and a potential for maternal transfer in these predominantly unregulated chemicals.

• Schultze, Sabrina; Langva, Hilde Kleppe; Wei, Jing; Chatzigeorgiou, Marios; Rundberget, Thomas & Hessen, Dag Olav [Show all 9 contributors for this article] (2024). Do DOM quality and origin affect the uptake and accumulation of a lipid-soluble contaminant in a filter feeding ascidian species (Ciona) that can target small particle size classes? Aquatic Toxicology. ISSN 0166-445X. 273. doi: 10.1016/j.aquatox.2024.107026. Full text in Research Archive Show summary

  The widely reported increase of terrestrial dissolved organic matter (terrDOM) in northern latitude coastal areas (“coastal darkening”) can impact contaminant dynamics in affected systems. One potential impact is based on differences in chemical adsorption processes of the molecularly larger terrDOM compared to marine DOM (marDOM) that leads to increased emulsification of lipophilic contaminants with terrDOM. Filter feeders filter large amounts of water and DOM daily and thus are directly exposed to associated contaminants through both respiration and feeding activity. Thus, increased exposure to terrDOM could potentially lead to an increase in bioaccumulation of lipid soluble contaminants in filter feeders. To assess the effect of DOM on bioaccumulation in filter feeders, we exposed the mucous based filter feeding ascidian Ciona intestinalis (formerly known as Ciona intestinalis Type B), to the lipophilic veterinary drug teflubenzuron (log KOW: 5.39) in combination with four DOM treatments: TerrDOM, marDOM, a mix of the two called mixDOM, and seawater without DOM addition. The exposure lasted for 15 days, after which the individuals in all DOM treatments showed a trend towards higher bioaccumulation of Teflubenzuron than those in the seawater control. However, there was considerable overlap in posterior distributions. Against our expectations, marDOM resulted in the highest bioaccumulation factor (BAF), followed by mixDOM, with terrDOM resulting in the lowest BAF except for seawater (kinetic BAF L/kg median, 2.5 %–97.5 % percentile marDOM 94, 74–118; mixDOM 82, 63–104; terrDOM 79; 61-99; seawater 61, 44–79). All BAFs were below the level of concern according to the EU REACH regulation (BAF < 2000 L / kg) and, therefore, likely not environmentally problematic in the examined context. However, the results show that DOM can act as a dietary vector; thus, different combinations of contaminants, DOM, and filter feeding organisms should be tested further.

• Holme, Jørn Andreas; Myhre, Oddvar & Øvrevik, Johan (2024). Adverse neurodevelopment in children associated with prenatal exposure to fine particulate matter (PM2.5) – Possible roles of polycyclic aromatic hydrocarbons (PAHs) and mechanisms involved. Reproductive Toxicology. ISSN 0890-6238. 130. doi: 10.1016/j.reprotox.2024.108718. Full text in Research Archive Show summary

  Prenatal exposure to ambient fine particles (PM2.5) and polycyclic aromatic hydrocarbons (PAHs) has been associated with adverse birth outcomes including neurodevelopmental effects with cognitive and/or behavioral implications in early childhood. As a background we first briefly summarize human studies on PM2.5 and PAHs associated with adverse birth outcomes and modified neurodevelopment. Next, we add more specific information from animal studies and in vitro studies and elucidate possible biological mechanisms. More specifically we focus on the potential role of PAHs attached to PM2.5 and explore whether effects of these compounds may arise from disturbance of placental function or more directly by interfering with neurodevelopmental processes in the fetal brain. Possible molecular initiating events (MIEs) include interactions with cellular receptors such as the aryl hydrocarbon receptor (AhR), beta-adrenergic receptors (βAR) and transient receptor potential (TRP)-channels resulting in altered gene expression. MIE linked to the binding of PAHs to cytochrome P450 (CYP) enzymes and formation of reactive electrophilic metabolites are likely less important. The experimental animal and in vitro studies support the epidemiological findings and suggest steps involved in mechanistic pathways explaining the associations. An overall evaluation of the doses/concentrations used in experimental studies combined with the mechanistic understanding further supports the hypothesis that prenatal PAHs exposure may cause adverse outcomes (AOs) linked to human neurodevelopment. Several MIEs will likely occur simultaneously in various cells/tissues involving several key events (KEs) which relative importance will depend on dose, time, tissue, genetics, other environmental factors, and neurodevelopmental endpoint in study.

• Langangen, Øystein Ole Gahr & Durant, Joël (2024). Persistence of fish populations to longer, more intense, and more frequent mass mortality events. Global Change Biology. ISSN 1354-1013. 30(3), p. 1–10. doi: 10.1111/gcb.17251. Full text in Research Archive Show summary

  Abstract Over the last decades, mass mortality events have become increasingly common across taxa with sometimes devastating effects on population biomass. In the aquatic environment, fish are sensitive to mass mortality events, particularly at the early life stages that are crucial for population dynamics. However, it has recently been shown for fish, that a single mass mortality event in early life typically does not lead to population collapse. Moreover, the frequency and intensity of extreme events that can cause mass mortality, such as marine heatwaves, are increasing. Here, we show that increasing frequency and intensity of mass mortality events may lead to population collapse. Since the drivers of mass mortality events are diverse, and often linked to climate change, it is challenging to predict the frequency and severity of future mass mortality events. As an alternative, we quantify the probability of population collapse depending on the frequency and intensity as well as the duration of mass mortality events. Based on 39 fish species, we show that the probability of collapse typically increases with increasing frequency, intensity, and duration of the mortality events. In addition, we show that the collapse depends on key traits such as natural mortality, recruitment variation, and density dependence. The presented framework provides quantitative estimates of the sensitivity of fish species to these increasingly common extreme events, which paves the way for potential mitigation actions to alleviate adverse impacts on harvested fish populations across the globe.

• Colls, Miriam; Viza, Aida; Zufiarre, Aitziber; Camacho-Santamans, Alba; Laini, Alex & González-Ferreras, Alexia Maria [Show all 85 contributors for this article] (2024). Impacts of diffuse urban stressors on stream benthic communities and ecosystem functioning: A review. Limnetica. ISSN 0213-8409. 43(1), p. 89–108. doi: 10.23818/limn.43.07. Full text in Research Archive Show summary

  Catchment urbanisation results in urban streams being exposed to a multitude of stressors. Notably, stressors originating from diffuse sources have received less attention than stressors originating from point sources. Here, advances related to diffuse urban stressors and their consequences for stream benthic communities are summarised by reviewing 92 articles. Based on the search criteria, the number of articles dealing with diffuse urban stressors in streams has been increasing, and most of them focused on North America, Europe, and China. Land use was the most common measure used to characterize diffuse stressor sources in urban streams (70.7 % of the articles characterised land use), and chemical stressors (inorganic nutrients, xenobiotics, metals, and water properties, including pH and conductivity) were more frequently reported than physical or biological stressors. A total of 53.3 % of the articles addressed the impact of urban stressors on macroinvertebrates, while 35.9 % focused on bacteria, 9.8 % on fungi, and 8.7 % on algae. Regarding ecosystem functions, almost half of the articles (43.5 %) addressed changes in community dynamics, 40.3 % addressed organic matter decomposition, and 33.9 % addressed nutrient cycling. When comparing urban and non-urban streams, the reviewed studies suggest that urbanisation negatively impacts the diversity of benthic organisms, leading to shifts in community composition. These changes imply functional degradation of streams. The results of the present review summarise the knowledge gained to date and identify its main gaps to help improve our understanding of urban streams.

• Möllerke, Anton; Brasse, Gregor; Bello, Jan; Vidal, Diogo Montes; Dettner, Konrad & Zettel, Jürg [Show all 10 contributors for this article] (2024). The unique epicuticular chemistry of Collembola – A cross-species analysis. iScience. 27(8). doi: 10.1016/j.isci.2024.110416. Full text in Research Archive Show summary

  Springtails (Collembola), tiny hexapod arthropods, are abundant in the soil of most ecosystems, but our knowledge of their secondary metabolites is limited, in contrast to that of insects. In insects, the outer cuticle is usually covered by mixtures of long-chain hydrocarbons serving different functions, such as water regulation or chemical communication. In contrast, the knowledge of the epicuticular chemistry of springtails is scarce. We analyzed the cuticular lipids of 23 species covering different lineages. The often complicated structures were elucidated using gas chromatography/mass spectrometry, microderivatization, and synthesis. In contrast to insects, the terpene biosynthetic pathway is used for many of these lipids, producing unprecedented higher terpenes. In addition, evidence for de novo cholesterol biosynthesis in springtails was found, which is absent in insects. Finally, diverse non-insect linear compounds originating from the fatty acid biosynthetic pathway were identified. Our comparative analysis showed clear differences compared to insects and shed light on phylogenetic relationships.

• Eliassen, Lasse Krøger; Garvang, Even Sletteng; Andersen, Tom; Engseth, Erik; Kristiansen, Kåre Andre & Wiik-Nielsen, Jannicke [Show all 7 contributors for this article] (2024). Conspicuous parasite modifies appearance and energetics of a marine copepod. ICES Journal of Marine Science. ISSN 1054-3139. 81(10), p. 2052–2064. doi: 10.1093/icesjms/fsae150. Full text in Research Archive Show summary

  Parasitism is an important driver of ecosystem processes. Copepods are fundamental trophic links in marine food webs and harbour many microeukaryotic parasites, but unreliable access to infected individuals limits quantitative studies of parasite infection costs. Calanus spp., (helgolandicus or finmarchicus), infected with the Yellow-Hyphal Parasite become pigmented and are found near the surface, suggesting predator-mediated dispersal. Conventional markers prevented phylogenetic inference but confirmed that the parasite is not Ichthyophonus hoferi, as previously thought. We identified the pigments, quantified the pigment content and respiration rate, and derived stable isotope signatures of infected and uninfected Calanus spp. to examine costs of infection. We found that the pigments were astaxanthin and β-carotene, associated with the host and parasite, respectively. Parasitized hosts had increased astaxanthin content, reduced respiration rate, and lower lipid content. Ultrastructure imaging revealed parasitic cells associated with lipids in the haemocoel. The changes to host phenotype have detrimental impacts on energetics and the ecology of Calanus. We discuss the role of pigments in parasite-host interactions and suggest that the parasite produces β-carotene pigment for its physiological benefits. The trade-off between physiological benefits of pigments and conspicuousness for parasites is relevant in zooplankton-host systems, as zooplankton rely heavily on transparency for survival.

• Christiansen, Svenja; Bråthen, Mabel Pernille; Moksnes, Fredrik Lund; Schmedling, Charlotte Aurora; Thorsby, Sara Jegstad & Titelman, Josefin [Show all 7 contributors for this article] (2024). Extensive avoidance behaviour of krill from predators and nets. ICES Journal of Marine Science. ISSN 1054-3139. 81(9), p. 1764–1773. doi: 10.1093/icesjms/fsae123. Full text in Research Archive Show summary

  We used echosounders to assess krill (Meganyctiphanes norvegica) responses to sampling gear and predators. Towing pelagic trawls above autonomous submerged, upward-looking echosounders revealed instantaneous diving by the krill during daytime but not at night. The krill dived at 10–30 cm s−1 with a near-simultaneous response throughout the krill layer below the gear (>10 m). Traversing the paths of the previous sampling revealed long-lasting voids in the krill distribution during the daytime. Such voids were less apparent at night. Backscatter increased in the wake of the gear during nocturnal sampling, possibly due to changes in individual backscatter related to variation in swimming behaviour. During daytime, krill responded to fish schools with instantaneous coherent diving, spanning tens of meters at speeds of 10–27 cm s−1. Coordinated and far-ranging responses indicate that even loose krill aggregations may facilitate predator avoidance by enabling efficient signal transmission between individuals. The krill antipredator behaviour instigated marked daytime krill patchiness. Krill patchiness will vary relative to the predator regime and reflect recent encounters.

• Hessen, Dag Olav; Milkoreit, Manjana & Nadeau, Christina (2024). Future Climate: Making Sense of the Long-Term to Ensure a Liveable Future. In Holand, Astrid Marie (Eds.), Time in Our Times: Stretching Contemporary Understandings of Time. De Gruyter Brill. ISSN 9783111428420. p. 101–124. doi: 10.1515/9783111428970-005. Full text in Research Archive
• Pérez, Géraldine; O'Leary, Bethan C.; Allegri, Elena; Casal, Gema; Cornet, Cindy C. & Juan, Silvia de [Show all 18 contributors for this article] (2024). A conceptual framework to help choose appropriate blue nature-based solutions. Journal of Environmental Management (JEM). ISSN 0301-4797. 352. doi: 10.1016/j.jenvman.2023.119936. Full text in Research Archive Show summary

  Biodiversity loss and climate change have severely impacted ecosystems and livelihoods worldwide, compromising access to food and water, increasing disaster risk, and affecting human health globally. Nature-based Solutions (NbS) have gained interest in addressing these global societal challenges. Although much effort has been directed to NbS in urban and terrestrial environments, the implementation of NbS in marine and coastal environments (blue NbS) lags. The lack of a framework to guide decision-makers and practitioners through the initial planning stages appears to be one of the main obstacles to the slow implementation of blue NbS. To address this, we propose an integrated conceptual framework, built from expert knowledge, to inform the selection of the most appropriate blue NbS based on desired intervention objectives and social-ecological context. Our conceptual framework follows a four incremental steps structure: Step 1 aims to identify the societal challenge(s) to address; Step 2 highlights ecosystem services and the underlying biodiversity and ecological functions that could contribute to confronting the societal challenge(s); Step 3 identify the specific environmental context the intervention needs to be set within (e.g. the spatial scale the intervention will operate within, the ecosystem's vulnerability to stressors, and its ecological condition); and Step 4 provides a selection of potential blue NbS interventions that would help address the targeted societal challenge(s) considering the context defined through Step 3. Designed to maintain, enhance, recover, rehabilitate, or create ecosystem services by supporting biodiversity, the blue NbS intervention portfolio includes marine protection (i.e., fully, highly, lightly, and minimally protected areas), restorative activities (i.e., active, passive, and partial restoration; rehabilitation of ecological function and ecosystem creation), and other management measures (i.e., implementation and enforcement of regulation). Ultimately, our conceptual framework guides decision-makers toward a versatile portfolio of interventions that cater to the specific needs of each ecosystem rather than imposing a rigid, one-size-fits-all model. In the future, this framework needs to integrate socio-economic considerations more comprehensively and be kept up-to-date by including the latest scientific information.

• Cristi, Antonia; Law, Cliff S.; Pinkerton, Matt; Santos, Adriana Lopes dos; Safi, Karl & Gutiérrez-Rodríguez, Andres (2024). Environmental driving forces and phytoplankton diversity across the Ross Sea region during a summer–autumn transition. Limnology and Oceanography. ISSN 0024-3590. 69, p. 772–788. doi: 10.1002/lno.12526. Full text in Research Archive Show summary

  The Ross Sea is a highly productive system characterized by a seasonal succession of phytoplankton groups. However, most of the current understanding is based on observations on the continental shelf in spring and summer at relatively coarse taxonomic resolution. Here, we characterize community composition (class to species) using V4-18S rRNA gene metabarcoding on transects to and across the Ross Sea (shelf-slope and oceanic subregions) during two voyages covering the Austral summer–autumn progression in successive years. Phytoplankton composition shifted from low-diversity diatom-dominated (50%) communities during the summer to more diverse dinoflagellate-dominated (48%) systems during the lower-productivity autumn season. Prymnesiophyceae abundance was low on both voyages (10%), except on the southeast shelf-slope, where Phaeocystis antarctica dominated a shallow mixed layer, contrary to its reported preference for deep-mixing conditions. Amplicon sequence variant analysis identified distinct spatial patterns for two P. antarctica genotypes yet clustered certain species of Bacillariophyta and Prymnesiophyceae, indicating similar environmental preference for genotypes in these groups. Multivariate analysis of environmental drivers found a higher correlation of community composition variation with salinity and macronutrients, but less so with mixed layer depth, considered a primary determinant of taxonomic composition in the Ross Sea. Comparison between years established that community composition was temporally more stable in oceanic relative to shelf-slope waters. This study of seasonal variation of phytoplankton community composition at finer taxonomic resolution provided insights into species- and strain-specific distribution, ecological preferences, and relationships to environmental conditions in the wider Ross Sea to inform modeling and projection of future regional changes.

• Sengupta, Sagnik & Leinaas, Hans Petter (2024). Phenotypic plasticity and thermal efficiency of temperature responses in two conspecific springtail populations from contrasting climates. Journal of Thermal Biology. ISSN 0306-4565. 123, p. 1–10. doi: 10.1016/j.jtherbio.2024.103914. Full text in Research Archive Show summary

  Temperature drives adaptation in life-history traits through direct effects on physiological processes. However, multiple life-history traits co-evolve as a life-history strategy. Therefore, physiological limitations constraining the evolution of trait means and phenotypic plasticity can be larger for some traits than the others. Comparisons of thermal responses across life-history traits can improve our understanding of the mechanisms determining the life-history strategies. In the present study, we focused on a soil microarthropod species abundant across the Northern Hemisphere, Folsomia quadrioculata (Collembola), with previously known effects of macroclimate. We selected an arctic and a temperate population from areas with highly contrasting climates — the arctic tundra and a coniferous forest floor, respectively — and compared them for thermal plasticity and thermal efficiency in growth, development, fecundity, and survival across four temperatures for a major part of their life cycle. We intended to understand the mechanisms by which temperature drives the evolution of life-history strategies. We found that the temperate population maximized performance at 10–15 °C, whereas the arctic population maintained its thermal efficiency across a wider temperature range (10–20 °C). Thermal plasticity varied in a trait-specific manner, and when considered together with differences in thermal efficiency, indicated that stochasticity in temperature conditions may be important in shaping the life-history strategies. Our study suggests that adopting a whole-organism approach and including physiological time considerations while analysing thermal adaptation will markedly improve our understanding of plausible links between thermal adaptation and responses to global climate change.

• Kvalheim, Lone; Stensrud, Eivind; Knutsen, Halvor; Hyvärinen, Olli Petteri & Eiler, Alexander (2024). Integration of citizen science and eDNA reveals novel ecological insights for marine fish conservation. Environmental DNA. 6(4). doi: 10.1002/edn3.584. Full text in Research Archive Show summary

  In the face of climate change, the accelerating nature crisis, and other anthropogenic impacts, conserving biodiversity demands effective monitoring. While innovative approaches have emerged to enhance biodiversity assessment, significant data gaps persist, particularly within marine ecosystems. In this study, we assess the utility of combining citizen (community) science with environmental DNA (eDNA) metabarcoding for characterizing and quantifying marine fish biodiversity. Over the summer of 2022, 32 volunteers conducted extensive water sampling in a large Norwegian fjord, yielding 96 samples. Contrasting eDNA findings with conventional observational surveys (such as a national species registration database and beach seine surveys) unveiled a substantial overlap in recorded species inventories. The eDNA citizen science initiative identified previously undocumented species and rediscovered others emphasizing an increase in warm-water species within the study area. Additionally, eDNA data unveiled reduced diversity within the inner fjord relative to the outer fjord. To conclude, our study demonstrates the successful integration of eDNA within a citizen science framework, facilitating comprehensive biodiversity tracking across coastal marine regions. These findings hold promise for advancing marine conservation efforts by providing valuable data to inform critical decision-making processes.

• Hessen, Dag Olav; Andersen, Tom; McKay, David Armstrong; Kosten, Sarian; Meerhoff, Mariana & Pickard, Amy [Show all 7 contributors for this article] (2024). Lake ecosystem tipping points and climate feedbacks. Earth System Dynamics (ESD). ISSN 2190-4979. 15(3), p. 653–669. doi: 10.5194/esd-15-653-2024. Full text in Research Archive
• Möllerke, Anton; Stell, Matthew; Schlawis, Christian; Trauer-Kizilelma, Ute; Herrmann, Jennifer & Leinaas, Hans Petter [Show all 8 contributors for this article] (2024). Identification of unique highly hetero-substituted benzenes as chemical weapons of springtails by a combination of trace analytical methods with DFT calculations and synthesis. Chemical Science. ISSN 2041-6520. 15, p. 15332–15338. doi: 10.1039/d4sc03182b. Full text in Research Archive Show summary

  Springtails (Collembola) are important members of the soil mesofauna. They are small, often less than 1–2 mm in length. A typical escape response of most surface-living species is to jump, using their furca. However, some species also use chemical defence against predators. While the defence chemistry of higher insects has been well studied, reports from the basal Collembola are rare, linked to the difficulties in obtaining enough biomass. We herein report on the identification and repellent activity of compounds detected in Ceratophysella denticulata. Extracts with various solvents obtained from only 50 individuals were sufficient for analysis by GC/MS, GC/HR-MS, and GC/IR. The large number of candidate structures of the major components were then prioritised by DFT calculations of IR spectra. Finally, the total synthesis of the top candidates confirmed the structures of the three major compounds to be 4-methoxy-5-(methylthio)benzo-1,3-dioxolane, 5,6,7-trimethoxybenzo-1,3-oxathiolane, and 8-amino-5,6,7-trimethoxybenzo-1,3-oxathiolane, the latter being the first naturally occurring fully hetero-substituted benzene. These highly substituted benzenes have no precedence in nature and carry structural motifs rare in nature, such as the benzo-1,3-oxathiolane ring system or the occurrence of O-, N-, and S-substituents at the same benzene core. Another novel natural compound, 2-methyl-1H-imidazo[4,5-b]pyridine, is used by Hypogastrura viatica. 4-Methoxy-5-(methylthio)benzo-1,3-dioxolane showed significant activity in deterrence assays with the ant Lasius niger. The data indicate that the title compounds are used in the chemical defence of these springtails, thus adding a new compound class to the known antipredator defences of arthropods. The results underline the difference in defence chemistry between Collembola and insects.

• Remili, Anaïs; Dietz, Rune; Sonne, Christian; Samarra, Filipa I. P.; Rikardsen, Audun H. & Kettemer, Lisa Elena [Show all 16 contributors for this article] (2023). Quantitative fatty acid signature analysis reveals a high level of dietary specialization in killer whales across the North Atlantic. Journal of Animal Ecology. ISSN 0021-8790. 92(6), p. 1216–1229. doi: 10.1111/1365-2656.13920. Full text in Research Archive Show summary

  Quantifying the diet composition of apex marine predators such as killer whales (Orcinus orca) is critical to assessing their food web impacts. Yet, with few exceptions, the feeding ecology of these apex predators remains poorly understood. Here, we use our newly validated quantitative fatty acid signature analysis (QFASA) approach on nearly 200 killer whales and over 900 potential prey to model their diets across the 5000 km span of the North Atlantic. Diet estimates show that killer whales mainly consume other whales in the western North Atlantic (Canadian Arctic, Eastern Canada), seals in the mid-North Atlantic (Greenland), and fish in the eastern North Atlantic (Iceland, Faroe Islands, Norway). Nonetheless, diet estimates also varied widely among individuals within most regions. This level of inter-individual feeding variation should be considered for future ecological studies focusing on killer whales in the North Atlantic and other oceans. These estimates reveal remarkable population- and individual-level variation in the trophic ecology of these killer whales, which can help to assess how their predation impacts community and ecosystem dynamics in changing North Atlantic marine ecosystems. This new approach provides researchers with an invaluable tool to study the feeding ecology of oceanic top predators.

• Crapart, Camille Marie; Finstad, Anders Gravbrøt; Hessen, Dag Olav; Vogt, Rolf David & Andersen, Tom (2023). Spatial predictors and temporal forecast of total organic carbon levels in boreal lakes. Science of the Total Environment. ISSN 0048-9697. 870. doi: 10.1016/j.scitotenv.2023.161676. Full text in Research Archive Show summary

  Browning of Fennoscandian boreal lakes is raising concerns for negative ecosystem impacts as well as reduced drinking water quality. Declined sulfur deposition and warmer climate, along with afforestation, other climate impacts and less outfield grazing, have resulted in increased fluxes of Total Organic Carbon (TOC) from catchments to freshwater, and subsequently to coastal waters. This study assesses the major governing factors for increased TOC levels among several catchment characteristics in almost 5000 Fennoscandian lakes and catchments. Normalized Difference Vegetation Index (NDVI), a proxy for plant biomass, and the proportions of peatland in the catchment, along with surface runoff intensity and nitrogen deposition loading, were identified as the main spatial predictors for lake TOC concentrations. A multiple linear model, based on these explanatory variables, was used to simulate future TOC concentration in surface runoff from coastal drainage basins in 2050 and 2100, using the forecasts of climatic variables in two of the Shared Socio-economic Pathways (SSP): 1-2.6 (+2 °C) and 3-7.0 (+4,5 °C). These scenarios yield contrasting effects. SSP 1-2.6 predicts an overall decrease of TOC export to coastal waters, while SSP 3-7.0 in contrast leads to an increase in TOC export.

• Holme, Jørn Andreas; Låg, Marit; Skuland, Tonje Schwach; Parenicová, Martina; Ciganek, Miroslav & Penciková, Katerina [Show all 13 contributors for this article] (2023). Characterization of elements, PAHs, AhR-activity and pro-inflammatory responses of road tunnel-derived particulate matter in human hepatocyte-like and bronchial epithelial cells. Toxicology in Vitro. ISSN 0887-2333. 90, p. 1–13. doi: 10.1016/j.tiv.2023.105611. Full text in Research Archive Show summary

  The aims were to characterize the content of elements and polycyclic aromatic hydrocarbons (PAHs) in size-separated particulate matter (PM) sampled in a road tunnel, estimate the contribution of PAHs to the toxic potential, and measure the pro-inflammatory potential of PM samples and extracts with increasing polarity. Several elements/metals previously associated with cytokine responses were found. Based on PAHs levels and published PAHs potency, the calculated mutagenic and carcinogenic activities of size-separated samples were somewhat lower for coarse than fine and ultrafine PM. The AhR-activity of the corresponding PM extracts measured in an AhR-luciferase reporter model (human hepatocytes) were more similar. The highest AhR-activity was found in the neutral (parent and alkylated PAHs) and polar (oxy-PAHs) fractions, while the semi-polar fractions (mono-nitrated-PAHs) had only weak activity. The neutral and polar aromatic fractions from coarse and fine PM were also found to induce higher pro-inflammatory responses and CYP1A1 expression in human bronchial epithelial cells (HBEC3-KT) than the semi-polar fractions. Fine PM induced higher pro-inflammatory responses than coarse PM. AhR-inhibition reduced cytokine responses induced by parent PM and extracts of both size fractions. Contributors to the toxic potentials include PAHs and oxy-PAHs, but substantial contributions from other organic compounds and/or metals are likely.

• Dinh, van Khuong; Albini, Dania; Orr, James A.; Macaulay, Samuel J.; Rillig, Matthias C. & Borgå, Katrine [Show all 7 contributors for this article] (2023). Winter is coming: Interactions of multiple stressors in winter and implications for the natural world. Global Change Biology. ISSN 1354-1013. 29(24), p. 6834–6845. doi: 10.1111/gcb.16956. Full text in Research Archive
• Marquardt, Miriam; Goraguer, Lucie Hélène Marie; Assmy, Philipp Kurt Wolf; Bluhm, Bodil Annikki Ulla Barbro; Aaboe, Signe & Down, Emily [Show all 12 contributors for this article] (2023). Seasonal dynamics of sea-ice protist and meiofauna in the northwestern Barents Sea. Progress in Oceanography. ISSN 0079-6611. 218. doi: 10.1016/j.pocean.2023.103128. Full text in Research Archive Show summary

  The rapid decline of Arctic sea ice makes understanding sympagic (ice-associated) biology a particularly urgent task. Here we studied the poorly known seasonality of sea-ice protist and meiofauna community composition, abundance and biomass in the bottom 30 cm of sea ice in relation to ice properties and ice drift trajectories in the northwestern Barents Sea. We expected low abundances during the polar night and highest values during spring prior to ice melt. Sea ice conditions and Chlorophyll a concentrations varied strongly seasonally, while particulate organic carbon concentrations were fairly stable throughout the seasons. In December to May we sampled growing first-year ice, while in July and August melting older sea ice dominated. Low sea-ice biota abundances in March could be related to the late onset of ice formation and short time period for ice algae and uni- and multicellular grazers to establish themselves. Pennate diatoms, such as Navicula spp. and Nitzschia spp., dominated the bottom ice algal communities and were present during all seasons. Except for May, ciliates, dinoflagellates, particularly of the order Gymnodiales, and small-sized flagellates were co-dominant. Ice meiofauna (here including large ciliates and foraminifers) was comprised mainly of harpacticoid copepods, copepod nauplii, rotifers, large ciliates and occasionally acoels and foraminifers, with dominance of omnivore species throughout the seasons. Large ciliates comprised the most abundant meiofauna taxon at all ice stations and seasons (50–90%) but did not necessarily dominate the biomass. While ice melt might have released and reduced ice algal biomass in July, meiofauna abundance remained high, indicating different annual cycles of protist versus meiofauna taxa. In May highest Chlorophyll a concentrations (29.4 mg m-2) and protist biomass (107 mg C m-2) occurred, while highest meiofauna abundance was found in August (23.9 × 103 Ind. m-2) and biomass in December (0.6 mg C m-2). The abundant December ice biota community further strengthens the emerging notion of an active biota during the dark Arctic winter. The data demonstrated a strong and partially unexpected seasonality in the Barents Sea ice biota, indicating that changes in ice formation, drift and decay will significantly impact the functioning of the ice-associated ecosystem.

• Kaartvedt, Stein; Christiansen, Svenja & Titelman, Josefin (2023). Mid-summer fish behavior in a high-latitude twilight zone. Limnology and Oceanography. ISSN 0024-3590. 68(7), p. 1654–1669. doi: 10.1002/lno.12374. Full text in Research Archive Show summary

  Abstract The behavior of the mesopelagic fish Benthosema glaciale was studied at 60°N in mid‐summer. We hypothesized that diel vertical migration (DVM) is constrained by short and dusk nights (surface illumination &gt; 10 −2   μ mol m −2 s −1 ) and that individuals are active at depth during the long summer days. Submerged echosounders provided high‐resolution data throughout the water column. During the day, a part of the population ascended toward the increasing daylight. Short vertical relocations were followed by minutes of vertical inactivity. Swimming included horizontal turns and loops associated with the vertical steps. Normal DVM was initiated ~ 4 h before sunset and reflected independent individual decisions. The fish initially ascended stepwise but switched to mostly straight upwards swimming attaining 3–4 cm s −1 . Their vertical speed was faster than the slow ascent of isolumes and even the deepest living fish potentially could reach upper layers shortly after sunset. However, many individuals aborted their ascent and returned to depth before the darkest time of the night, while others returned downward closer to sunrise. The daytime swimming and individual variability in diel migration behavior have implications for encounters with prey and predators in the twilight zone and the biological carbon pump. A principal conclusion is that mesopelagic fishes can modify their behavior and migration patterns to suit a wide range of changing conditions.

• Morrissey, Christy; Fritsch, Clémentine; Fremlin, Katharine; Adams, William; Borgå, Katrine & Brinkmann, Markus [Show all 11 contributors for this article] (2023). Advancing exposure assessment approaches to improve wildlife risk assessment. Integrated Environmental Assessment and Management. ISSN 1551-3777. doi: 10.1002/ieam.4743. Full text in Research Archive Show summary

  The exposure assessment component of a Wildlife Ecological Risk Assessment aims to estimate the magnitude, frequency, and duration of exposure to a chemical or environmental contaminant, along with characteristics of the exposed population. This can be challenging in wildlife as there is often high uncertainty and error caused by broad-based, interspecific extrapolation and assumptions often because of a lack of data. Both the US Environmental Protection Agency (USEPA) and European Food Safety Authority (EFSA) have broadly directed exposure assessments to include estimates of the quantity (dose or concentration), frequency, and duration of exposure to a contaminant of interest while considering “all relevant factors.” This ambiguity in the inclusion or exclusion of specific factors (e.g., individual and species-specific biology, diet, or proportion time in treated or contaminated area) can significantly influence the overall risk characterization. In this review, we identify four discrete categories of complexity that should be considered in an exposure assessment—chemical, environmental, organismal, and ecological. These may require more data, but a degree of inclusion at all stages of the risk assessment is critical to moving beyond screening-level methods that have a high degree of uncertainty and suffer from conservatism and a lack of realism. We demonstrate that there are many existing and emerging scientific tools and cross-cutting solutions for tackling exposure complexity. To foster greater application of these methods in wildlife exposure assessments, we present a new framework for risk assessors to construct an “exposure matrix.” Using three case studies, we illustrate how the matrix can better inform, integrate, and more transparently communicate the important elements of complexity and realism in exposure assessments for wildlife. Modernizing wildlife exposure assessments is long overdue and will require improved collaboration, data sharing, application of standardized exposure scenarios, better communication of assumptions and uncertainty, and postregulatory tracking.

• Wei, Jing; Fontaine, Laurent; Parra, Nicolas Valiente; Dörsch, Peter; Hessen, Dag Olav & Eiler, Alexander (2023). Trajectories of freshwater microbial genomics and greenhouse gas saturation upon glacial retreat. Nature Communications. 14. doi: 10.1038/s41467-023-38806-w. Full text in Research Archive Show summary

  Abstract Due to climate warming, ice sheets around the world are losing mass, contributing to changes across terrestrial landscapes on decadal time spans. However, landscape repercussions on climate are poorly constrained mostly due to limited knowledge on microbial responses to deglaciation. Here, we reveal the genomic succession from chemolithotrophy to photo- and heterotrophy and increases in methane supersaturation in freshwater lakes upon glacial retreat. Arctic lakes at Svalbard also revealed strong microbial signatures form nutrient fertilization by birds. Although methanotrophs were present and increased along lake chronosequences, methane consumption rates were low even in supersaturated systems. Nitrous oxide oversaturation and genomic information suggest active nitrogen cycling across the entire deglaciated landscape, and in the high Arctic, increasing bird populations serve as major modulators at many sites. Our findings show diverse microbial succession patterns, and trajectories in carbon and nitrogen cycle processes representing a positive feedback loop of deglaciation on climate warming.

• Caillon, Coline; Pernet, Fabrice; Lutier, Mathieu & Poi, Carole Di (2023). Differential reaction norms to ocean acidification in two oyster species from contrasting habitats. Journal of Experimental Biology. ISSN 0022-0949. 226(23), p. 1–11. doi: 10.1242/jeb.246432. Full text in Research Archive
• Andvik, Clare; Bories, Pierre; Harju, Mikael; Borgå, Katrine; Jourdain, Eve & Karoliussen, Richard [Show all 9 contributors for this article] (2023). Phthalate contamination in marine mammals off the Norwegian coast. Marine Pollution Bulletin. ISSN 0025-326X. 199. doi: 10.1016/j.marpolbul.2023.115936. Full text in Research Archive Show summary

  Phthalates are used in plastics, found throughout the marine environment and have the potential to cause adverse health effects. In the present study, we quantified blubber concentrations of 11 phthalates in 16 samples from stranded and/or free-living marine mammals from the Norwegian coast: the killer whale (Orcinus orca), sperm whale (Physeter macrocephalus), long-finned pilot whale (Globicephala melas), white-beaked dolphin (Lagenorhynchus albirostris), harbour porpoise (Phocoena phocoena), and harbour seal (Phoca vitulina). Five compounds were detected across all samples: benzyl butyl phthalate (BBP; in 50 % of samples), bis(2-ethylhexyl) phthalate (DEHP; 33 %), diisononyl phthalate (DiNP; 33 %), diisobutyl phthalate (DiBP; 19 %), and dioctyl phthalate (DOP; 13 %). Overall, the most contaminated individual was the white-beaked dolphin, whilst the lowest concentrations were measured in the killer whale, sperm whale and long-finned pilot whale. We found no phthalates in the neonate killer whale. The present study is important for future monitoring and management of these toxic compounds.

• Bjorbækmo, Marit Frederikke Markussen; Brodie, Juliet; Krabberød, Anders Kristian; Logares, Ramiro; Fuss, Janina & Fredriksen, Stein [Show all 9 contributors for this article] (2023). 18S rDNA gene metabarcoding of microeukaryotes and epi-endophytes in the holobiome of seven species of large brown algae. Journal of Phycology. ISSN 0022-3646. 59(5), p. 859–878. doi: 10.1111/jpy.13377. Full text in Research Archive Show summary

  Brown algae (Phaeophyceae) are habitat-forming species in coastal ecosystems and include kelp forests and seaweed beds that support a wide diversity of marine life. Host-associated microbial communities are an integral part of phaeophyte biology, and whereas the bacterial microbial partners have received considerable attention, the microbial eukaryotes associated with brown algae have hardly been studied. Here, we used broadly targeted “pan-eukaryotic” primers (metabarcoding) to investigate brown algal-associated eukaryotes (the eukaryome). Using this approach, we aimed to investigate the eukaryome of seven large brown algae that are important and common species in coastal ecosystems. We also aimed to assess whether these macroalgae harbor novel eukaryotic diversity and to ascribe putative functional roles to the host-associated eukaryome based on taxonomic affiliation and phylogenetic placement. We detected a significant diversity of microeukaryotic and algal lineages associated with the brown algal species investigated. The operational taxonomic units (OTUs) were taxonomically assigned to 10 of the eukaryotic major supergroups, including taxonomic groups known to be associated with seaweeds as epibionts, endobionts, parasites, and commensals. Additionally, we revealed previously unrecorded sequence types, including novel phaeophyte OTUs, particularly in the Fucus spp. samples, that may represent fucoid genomic variants, sequencing artifacts, or undescribed epi-/endophytes. Our results provide baseline data and technical insights that will be useful for more comprehensive seaweed eukaryome studies investigating the evidently lineage-rich and functionally diverse symbionts of brown algae.

• Schultze, Sabrina; Andersen, Tom; Knudtzon, Nina; Ruus, Anders; Rundberget, Jan T. & Brooks, Steven J. [Show all 9 contributors for this article] (2023). Do DOM quality and origin affect the uptake and accumulation of lipid-soluble contaminants in coastal filter feeders? An experimental simulation of teflubenzuron exposure to blue mussels. Aquatic Toxicology. ISSN 0166-445X. 263. doi: 10.1016/j.aquatox.2023.106696. Full text in Research Archive Show summary

  The increased export of terrestrial dissolved organic matter (terrDOM) to coastal marine ecosystems may affect local filter feeders and the local food web via the altered uptake of organic material and associated contaminants. To compare terrDOM to marine DOM (marDOM) as contaminant vectors to coastal biota, we exposed blue mussels (Mytilus sp.) to the different DOM types in combination with teflubenzuron, a widely applied lipophilic aquaculture medicine targeting salmon lice (Lepeophtheirus salmonis). A 16-day exposure of the blue mussels to DOM and teflubenzuron was followed by a depuration phase of 20 days without teflubenzuron. We calculated teflubenzuron adsorption rates and bioaccumulation factors (BAF) using a Bayesian model, expecting teflubenzuron uptake to be greater with terrDOM than marDOM due to the higher prevalence of large amphipathic humic acids in terrDOM. Humic acids have strong absorption properties and are able to envelope lipophilic molecules. Thus, humic acids can function as an efficient contaminant vector when taken up by filter feeders. Although there were varying degrees of overlap, the mussels tended to accumulate higher amounts of teflubenzuron in the DOM treatments than in the seawater control (bioaccumulation factor [BAF] in seawater: median 106 L/kg; 2.5 %–97.5 % percentile: 69–160 L/kg). Contrary to expectations, mussels exposed to marDOM showed a trend toward more bioaccumulation of teflubenzuron than those exposed to terrDOM (BAF marine 144 L/kg; 102–221 L/kg versus BAF terrestrial: 121 L/kg; 82–186 L/kg). The highest teflubenzuron accumulation was observed with the 50:50 mixture of marDOM and terrDOM (BAF mix: 165 L/kg; 117–244 L/kg). The slight difference in DOM-type accumulation rates observed in this experiment—especially the accumulation rate of terrDOM compared to that of the seawater-only treatment type—was not considered environmentally relevant. Further studies are necessary to see if the observed trends transfer to complex environmental systems.

• Xu, Xiangbo; Xu, Yan; Li, Jing; Lu, Yonglong; Jenkins, Alan & Ferrier, Robert C. [Show all 16 contributors for this article] (2023). Coupling of crop and livestock production can reduce the agricultural GHG emission from smallholder farms. iScience. 26(6), p. 1–13. doi: 10.1016/j.isci.2023.106798. Full text in Research Archive Show summary

  Ensuring global food security and environmental sustainability is dependent upon the contribution of the world’s hundred million smallholder farms, but the contributions of smallholder farms to global agricultural greenhouse gas (GHG) emissions have been understudied. We developed a localized agricultural life cycle assessment (LCA) database to calculate GHG emissions and made the first extensive assessment of the smallholder farms’ GHG emission reduction potentials by coupling crop and livestock production (CCLP), a redesign of current practices toward sustainable agriculture in China. CCLP can reduce the GHG emission intensity by 17.67%, with its own feed and manure returning to the field as an essential path. Scenario analysis verified that greater GHG emission reduction (28.09%–41.32%) will be achieved by restructuring CCLP. Therefore, this mixed farming is a mode with broader benefits to provide sustainable agricultural practices for reducing GHG emissions fairly.

• Ngo, Van Manh; Dinh, van Khuong; Chau, Bich Lien & Luc, Diep Minh (2023). Tank colours do not change the effects of extreme temperatures on the productive parameters, but skeletal deformities of golden trevally. Fisheries and Aquatic Sciences (FAS). ISSN 2234-1749. 26(8), p. 461–469. doi: 10.47853/FAS.2023.e39. Full text in Research Archive Show summary

  The objective of this study was to evaluate how the tank colours may change the effects of extreme temperature on the survival, growth, and quality of juvenile golden trevally (Gnathanodon speciosus). The experiment was set up with fifteen treatments of five tank colours (blue, red, yellow, grey, and white) and three temperatures (30°C, 32°C, 34°C) with three replications. Fish performance was assessed for four weeks. The results showed that tank colours and elevated temperatures affected the quality of golden trevally juveniles. The survival and growth rate of fish tend to decrease gradually, but the deformation rate of fish tended to increase in the order of tank colours: red, yellow > grey, blue, and white. The growth and survival rate of fish gradually decreased when the rearing temperature increased from 30°C to 34°C and this effect was independent of tank colors. Importantly, the deformation rate increased under elevated temperature, particularly in blue and white tanks with potential long-term effects. It is, therefore, not recommended to use blue and white tanks for rearing the golden trevally juveniles, particularly during extremely high temperatures from heatwave events.

• Shi, Yingying; Wei, Zhipeng; Xu, Yaofei; Lu, Xiang & Ruan, Aidong (2023). Effects of electrochemical intervention on the remediation of black-odorous water: insights into microbial community dynamics and functional shifts in sediments. Water Science and Technology. ISSN 0273-1223. 87(11), p. 2776–2792. doi: 10.2166/wst.2023.169. Full text in Research Archive Show summary

  Black-odorous water is a severe environmental issue that has received continuous attention. The major purpose of the present study was to propose an economical, practical, and pollution-free treatment technology. In this study, the in situ remediation of black-odorous water was conducted by applying different voltages (2.5, 5, and 10 V) to improve oxidation conditions of the surface sediments. The study investigated the effects of voltage intervention on water quality, gas emissions, and microbial community dynamics in surface sediments during the remediation process. The results indicated that the voltage intervention can effectively increase the oxidation–reduction potential (ORP) of the surface sediments and inhibit the emissions of H2S, NH3, and CH4. Moreover, the relative abundances of typical methanogens (Methanosarcina and Methanolobus) and sulfate-reducing bacteria (Desulfovirga) decreased because of the increase in ORP after the voltage treatment. The microbial functions predicted by FAPROTAX also demonstrated the inhibition of methanogenesis and sulfate reduction functions. On the contrary, the total relative abundances of chemoheterotrophic microorganisms (e.g., Dechloromonas, Azospira, Azospirillum, and Pannonibacter) in the surface sediments increased significantly, which led to enhanced biochemical degradability of the black-odorous sediments as well as CO2 emissions.

• Burgunter-Delamare, Bertille; Rousvoal, Sylvie; Legeay, Erwan; Tanguy, Gwenn; Fredriksen, Stein & Boyen, Catherine [Show all 7 contributors for this article] (2023). The Saccharina latissima microbiome: Effects of region, season, and physiology. Frontiers in Microbiology. 13, p. 1–16. doi: 10.3389/fmicb.2022.1050939. Full text in Research Archive Show summary

  Introduction Saccharina latissima is a canopy-forming species of brown algae and, as such, is considered an ecosystem engineer. Several populations of this alga are exploited worldwide, and a decrease in the abundance of S. latissima at its southern distributional range limits has been observed. Despite its economic and ecological interest, only a few data are available on the composition of microbiota associated with S. latissima and its role in algal physiologyn. Methods We studied the whole bacterial community composition associated with S. latissima samples from three locations (Brittany, Helgoland, and Skagerrak) by 16S metabarcoding analyses at different scales: algal blade part, regions, season (at one site), and algal physiologic state. Results and Discussion We have shown that the difference in bacterial composition is driven by factors of decreasing importance: (i) the algal tissues (apex/meristem), (ii) the geographical area, (iii) the seasons (at the Roscoff site), and (iv) the algal host’s condition (healthy vs. symptoms). Overall, Alphaproteobacteria , Gammaproteobacteria , and Bacteroidia dominated the general bacterial communities. Almost all individuals hosted bacteria of the genus Granulosicoccus , accounting for 12% of the total sequences, and eight additional core genera were identified. Our results also highlight a microbial signature characteristic for algae in poor health independent of the disease symptoms. Thus, our study provides a comprehensive overview of the S. latissima microbiome, forming a basis for understanding holobiont functioning.

• Thiele, Stefan; Vader, Anna; Thomson, Stuart; Saubrekka, Karoline; Petelenz-Kurdziel, Elzbieta Anna & Müller, Oliver [Show all 8 contributors for this article] (2023). Seasonality of the bacterial and archaeal community composition of the Northern Barents Sea. Frontiers in Microbiology. 14. doi: 10.3389/fmicb.2023.1213718. Full text in Research Archive Show summary

  The Barents Sea is a transition zone between the Atlantic and the Arctic Ocean. The ecosystem in this region is highly variable, and a seasonal baseline of biological factors is needed to monitor the effects of global warming. In this study, we report the results from the investigations of the bacterial and archaeal community in late winter, spring, summer, and early winter along a transect through the northern Barents Sea into the Arctic Ocean east of Svalbard using 16S rRNA metabarcoding. Winter samples were dominated by members of the SAR11 clade and a community of nitrifiers, namely Cand. Nitrosopumilus and LS-NOB (Nitrospinia), suggest a prevalence of chemoautotrophic metabolisms. During spring and summer, members of the Gammaproteobacteria (mainly members of the SAR92 and OM60(NOR5) clades, Nitrincolaceae) and Bacteroidia (mainly Polaribacter, Formosa, and members of the NS9 marine group), which followed a succession based on their utilization of different phytoplankton-derived carbon sources, prevailed. Our results indicate that Arctic marine bacterial and archaeal communities switch from carbon cycling in spring and summer to nitrogen cycling in winter and provide a seasonal baseline to study the changes in these processes in response to the effects of climate change.

• Durant, Joël; Holt, Rebecca Emma; Ono, Kotaro & Langangen, Øystein Ole Gahr (2023). Predatory walls may impair climate warming-associated population expansion. Ecology. ISSN 0012-9658. 104(9), p. 1–8. doi: 10.1002/ecy.4130. Full text in Research Archive Show summary

  Climate change has a profound impact on species distribution and abundanceglobally, as well as local diversity, which affects ecosystem functioning. In par-ticular, changes in population distribution and abundance may lead tochanges in trophic interactions. Although species can often shift their spatialdistribution when suitable habitats are available, it has been suggested thatpredator presence can be a constraint on climate-related distribution shifts.We test this using two well-studied and data-rich marine environments.Focusing on a pair of sympatric fishes, Atlantic haddock Melanogrammus aeglefinus and cod Gadus morhua, we study the effect of the presence andabundance of the latter on the former distribution. We found that the distribu-tion of cod and increased abundance may limit the expansion of haddock tonew areas and could consequently buffer ecosystem changes due to climatechange. Though marine species may track the rate and direction of climateshifts, our results demonstrate that the presence of predators may limit theirexpansion to thermally suitable habitats. By integrating climatic and ecologicaldata at scales that can resolve predator–prey relationships, this analysis dem-onstrates the usefulness of considering trophic interactions to gain a morecomprehensive understanding and to mitigate the effects of climate change onspecies distributions.

• Ahme, Antonia; Happe, Anika; Striebel, Maren; Olsson, Markus; Giesler, Jakob & Kline, Simon Hasselø [Show all 7 contributors for this article] (2023). Thermal performance assay of a plankton community from Helgoland Roads for an indoor mesocosm experiment in March 2022. PANGAEA. Data Publisher for Earth & Environmental Science. doi: 10.1594/PANGAEA.961508. Full text in Research Archive
• Ahme, Antonia; Happe, Anika; Striebel, Maren; Olsson, Markus; Kühne, Nancy & Giesler, Jakob [Show all 16 contributors for this article] (2023). Temperature effects on a plankton community from Helgoland Roads tested in an indoor mesocosm experiment in March 2022. PANGAEA. Data Publisher for Earth & Environmental Science. doi: 10.1594/PANGAEA.961155. Full text in Research Archive
• Vereide, Emilie Hernes; Mihaljevic, Marina; Browman, Howard; Fields, David M.; Agersted, Mette Dalgaard & Titelman, Josefin [Show all 7 contributors for this article] (2023). Effects of airgun discharges used in seismic surveys on development and mortality in nauplii of the copepod Acartia tonsa. Environmental Pollution. ISSN 1566-0745. 327. doi: 10.1016/j.envpol.2023.121469. Full text in Research Archive Show summary

  Seismic surveys are conducted worldwide to explore for oil and gas deposits and to map subsea formations. The airguns used in these surveys emit low-frequency sound waves. Studies on zooplankton responses to airguns report a range of effects, from none to substantial mortality. A field experiment was conducted to assess mortality and naupliar body length of the calanoid copepod Acartia tonsa when exposed to the discharge of two 40-inch airguns. Nauplii were placed in plastic bags and attached to a line at a depth of 6 m. For each treatment, three bags of nauplii were exposed to one of three treatments for 2.5 h: Airgun array discharge, a boat control, or a silent control. After exposure, nauplii were kept in filtered seawater in the laboratory without food. Immediate mortality in the nauplii was approximately 14% compared to less than 4% in the silent and boat control. Similarly, there was higher mortality in the airgun exposed nauplii up to six days after exposure compared to the control treatments. Nearly all of the airgun exposed nauplii were dead after four days, while >50% of the nauplii in the control treatments were alive at six days post-exposure. There was an interaction between treatment and time on naupliar body length, indicating lower growth in the nauplii exposed to the airgun discharge (growth rates after 4 days: 1.7, 5.4, and 6.1 μm d−1 in the airgun exposed, silent control, and boat control, respectively). These experiments indicate that the output of two small airguns affected mortality and growth of the naupliar stages of Acartia tonsa in close vicinity to the array.

• Pham, Hung Quoc; Bui, Canh Van; Doan, Nam Xuan & Dinh, van Khuong (2023). Density effects on a tropical copepod Acartia sp.: Implications as live feed in aquaculture. Journal of the World Aquaculture Society. ISSN 0893-8849. p. 1–12. doi: 10.1111/jwas.13020. Full text in Research Archive Show summary

  Abstract Calanoid copepods Acartia species are major live feeds for the early stages of economically important marine fish in hatcheries in Southeast Asian countries. However, rearing Acartia copepods at high densities to increase productivity remains a major challenge. To address the issue, we conducted two experiments on (1) Acartia sp. nauplii (1000, 3000, 6000, 9000, 12,000, and 15,000 individuals L −1 ) and (2) adults (1000, 1500, 2000, and 2500 individuals L −1 ). We assessed key parameters for biomass production: development, survival, and egg and nauplii production. In general, increased density resulted in longer development time, lowered survival and egg and nauplii production but did not affect the size of adult males and females. Despite survival to adulthood decreasing at higher stocking nauplii densities, the number of surviving adults was highest at a stocking density of 12,000 individuals L −1 . Egg and nauplii production was very low which may be the result of high predation. The total eggs and nauplii harvested were highest at the lowest adult density. These results are essential for the biomass production of Acartia sp. in central Vietnam.

• Monteith, Donald T.; Henrys, Peter A.; Hruška, Jakub; Wit, Heleen de; Krám, Pavel & Moldan, Filip [Show all 12 contributors for this article] (2023). Long-term rise in riverine dissolved organic carbon concentration is predicted by electrolyte solubility theory. Science Advances. 9(3). doi: 10.1126/sciadv.ade3491. Full text in Research Archive Show summary

  The riverine dissolved organic carbon (DOC) flux is of similar magnitude to the terrestrial sink for atmospheric CO2, but the factors controlling it remain poorly determined and are largely absent from Earth system models (ESMs). Here, we show, for a range of European headwater catchments, that electrolyte solubility theory explains how declining precipitation ionic strength (IS) has increased the dissolution of thermally moderated pools of soluble soil organic matter (OM), while hydrological conditions govern the proportion of this OM entering the aquatic system. Solubility will continue to rise exponentially with declining IS until pollutant ion deposition fully flattens out under clean air policies. Future DOC export will increasingly depend on rates of warming and any directional changes to the intensity and seasonality of precipitation and marine ion deposition. Our findings provide a firm foundation for incorporating the processes dominating change in this component of the global carbon cycle in ESMs.

• Nowicki, Robynne; Borgå, Katrine; Gabrielsen, Geir W. & Varpe, Øystein (2023). Energy content of krill and amphipods in the Barents Sea from summer to winter: variation across species and size. Polar Biology. ISSN 0722-4060. 46, p. 139–150. doi: 10.1007/s00300-023-03112-0. Full text in Research Archive Show summary

  Arctic zooplankton develop large energy reserves, as an adaptation to strong seasonality, making them valuable prey items. We quantified the energy content (kJ g−1 dry weight) of abundant krill (arcto-boreal, Thysanoessa inermis and boreal, Meganyctiphanes norvegica) and amphipods (Arctic, Themisto libellula and sub-Arctic-boreal, Themisto abyssorum) in the Barents Sea in late summer (August) and early winter (December). Variation in energy content was attributed to species-specific traits and body size categories, the latter in part as a proxy for ontogeny. T. inermis had the highest energy content, (Aug: 26.8 ± 1.5 (SD) kJ g−1) and remained similar from summer to winter. Energy content increased in M. norvegica and decreased in both amphipod species, with the lowest energy content being in T. abyssorum (Dec: 17.8 ± 0.8 kJ g−1). The effect of body size varied between species, with energy content increasing with size in T. inermis and T. libellula, and no change with size in M. norvegica and T. abyssorum. The reproductive stages of T. libellula differed in energy content, being highest in gravid females. Energy content varied with species’ dependence on energy storage. Our findings highlight how phylogenetically and morphologically similar prey items cannot necessarily be considered equal from a predator´s perspective. Energetically, the northern T. inermis was higher quality compared to the more southern M. norvegica, and mostly so during summer. Ecological models and management strategies should consider such variation in prey quality, especially as Arctic borealization is expected to change species composition and the energetic landscape for predators.

• Bustnes, Jan Ove; Bårdsen, Bård-Jørgen; Moe, Børge; Herzke, Dorte; Ballesteros, Manuel & Fenstad, Anette [Show all 12 contributors for this article] (2023). Impacts of a warming climate on concentrations of organochlorines in a fasting high arctic marine bird: Direct vs. indirect effects? Science of the Total Environment. ISSN 0048-9697. 908. doi: 10.1016/j.scitotenv.2023.168096. Full text in Research Archive Show summary

  The present study examined how climate changes may impact the concentrations of lipophilic organochlorines (OCs) in the blood of fasting High Arctic common eiders (Somateria mollissima) during incubation. Polychlorinated biphenyls (PCBs), 1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p′-DDE), hexachlorobenzene (HCB) and four chlordane compounds (oxychlordane, trans-chlordane and trans- and cis-nonachlor) were measured in females at chick hatching (n = 223) over 11 years (2007–2017). Firstly, median HCB and p,p′-DDE concentrations increased ~75 % over the study period, whereas median chlordane concentrations doubled (except for oxychlordane). PCB concentrations, in contrast, remained stable over the study period. Secondly, both body mass and clutch size were negatively associated with OC levels, suggesting that females with high lipid metabolism redistributed more OCs from adipose tissue, and that egg production is an important elimination route for OCs. Thirdly, the direct climate effects were assessed using the mean effective temperature (ET: air temperature and wind speed) during incubation, and we hypothesized that a low ET would increase redistribution of OCs. Contrary to expectation, the ET was positively correlated to most OCs, suggesting that a warmer climate may lead to higher OCs levels, and that the impact of ET may not be direct. Finally, potential indirect impacts were examined using the Arctic Oscillation (AO) in the three preceding winters (AOwinter 1–3) as a proxy for potential long-range transport of OCs, and for local spring climate conditions. In addition, we used chlorophyll a (Chla) as a measure of spring primary production. There were negative associations between AOwinter 1 and HCB, trans-chlordane and trans-nonachlor, whereas oxychlordane and cis-chlordane were negatively associated with Chla. This suggests that potential indirect climate effects on eiders were manifested through the food chain and not through increased long-range transport, although these relationships were relatively weak.

• Gormley, Kate; Hague, Emily; Andvik, Clare Margaret; DaCosta, Valentina; Davies, Abigail & Diz, Daniela [Show all 8 contributors for this article] (2023). First port of call: a horizon scanning workshop for sustainable Arctic marine infrastructure. The Polar Journal. ISSN 2154-896X. 13(1), p. 146–162. doi: 10.1080/2154896X.2023.2205243. Full text in Research Archive Show summary

  To support the predicted growth of shipping activities in the Arctic region in coming decades, port developments and associated shipping infrastructure will be required to be developed in both Arctic and sub-Arctic areas. Such large-scale development in unique and potentially vulnerable areas are likely to have wide-ranging effects and associated impacts. We therefore consider the future challenges, opportunities and knowledge gaps associated with the environmental impacts of developing Arctic and sub-Arctic port infrastructure. Here we present the outputs of an international, virtual workshop held in January 2022 exploring this theme. The workshop brought together Arctic, marine and port researchers, practitioners, non-governmental organisations, and local communities representing a range of geographies and disciplines. Based on pre-workshop consultation, five topics were considered: marine mammals and noise; discharges and pollution; ecosystem impacts and effects; environmental management and assessment; and infrastructure and geography. Dissemination of the workshop found five overriding themes that were common across each topic discussion: i) utilising best practice and governance; ii) community and Indigenous Peoples engagement and participation; iii) common vs. Arctic-specific challenges; iv) impact assessment including consideration of cumulative impacts and effects; and v) climate change. The workshop highlighted the requirement to continue to build and broaden discussion, for further collaborative work and research streams to be developed, to ensure any future Arctic and sub-Arctic port infrastructure, in support of Arctic shipping, is developed sustainably.

• Möllerke, Anton; Bello, Jan; Leinaas, Hans Petter & Schulz, Stefan (2023). Cyclopropane Hydrocarbons from the Springtail Vertagopus sarekensis─A New Class of Cuticular Lipids from Arthropods. Journal of natural products. ISSN 0163-3864. 87(1), p. 85–97. doi: 10.1021/acs.jnatprod.3c00789. Full text in Research Archive Show summary

  The epicuticle of insects is usually coated with a complex mixture of hydrocarbons, primarily straight-chain and methyl-branched alkanes and alkenes. We were interested in whether springtails (Collembola), a sister class of the insects, also use such compounds. We focused here on Vertagopus sarekensis, an abundant Isotomidae species in European high alpine regions, exhibiting coordinated group behavior and migration. This coordination, suggesting chemical communication, made the species interesting for our study on epicuticular hydrocarbons in springtails with different degrees of group behavior. We isolated a single hydrocarbon from its surface, which is the major epicuticular lipid. The structure was deduced by NMR analysis and GC/MS including derivatization. Total synthesis confirmed the structure as cis,cis-3,4,13,14-bismethylene-24-methyldotriacontane (4, sarekensane). The GC/MS analyses of some other cyclopropane hydrocarbons also synthesized showed the close similarity of both mass spectra and gas chromatographic retention indices of alkenes and cyclopropanes. Therefore, analyses of cuticular alkenes must be performed with appropriate derivatization to distinguish these two types of cuticular hydrocarbons. Sarekensane (4) is the first nonterpenoid cuticular hydrocarbon from Collembola that is biosynthesized via the fatty acid pathway, as are insect hydrocarbons, and contains unprecedented cyclopropane rings in the chain, not previously reported from arthropods.

• Cembella, Allan; Klemm, Kerstin; John, Uwe; Karlson, Bengt; Arneborg, Lars & Clarke, Dave [Show all 12 contributors for this article] (2023). Emerging phylogeographic perspective on the toxigenic diatom genus Pseudo-nitzschia in coastal northern European waters and gateways to eastern Arctic seas: Causes, ecological consequences and socio-economic impacts. Harmful Algae. ISSN 1568-9883. 129. doi: 10.1016/j.hal.2023.102496. Full text in Research Archive Show summary

  The diatom Pseudo-nitzschia H. Peragallo is perhaps the most intensively researched genus of marine pennate diatoms, with respect to species diversity, life history strategies, toxigenicity, and biogeographical distribution. The global magnitude and consequences of harmful algal blooms (HABs) of Pseudo-nitzschia are particularly significant because of the high socioeconomic impacts and environmental and human health risks associated with the production of the neurotoxin domoic acid (DA) among populations of many (although not all) species. This has led to enhanced monitoring and mitigation strategies for toxigenic Pseudo-nitzschia blooms and their toxins in recent years. Nevertheless, human adaptive actions based on future scenarios of bloom dynamics and proposed shifts in biogeographical distribution under climate-change regimes have not been implemented on a regional scale. In the CoCliME (Co-development of climate services for adaptation to changing marine ecosystems) program these issues were addressed with respect to past, current and anticipated future status of key HAB genera such as Pseudo-nitzschia and expected benefits of enhanced monitoring. Data on the distribution and frequency of Pseudo-nitzschia blooms in relation to DA occurrence and associated amnesic shellfish toxin (AST) events were evaluated in a contemporary and historical context over the past several decades from key northern CoCliME Case Study areas. The regional studies comprised the greater North Sea and adjacent Kattegat-Skagerrak and Norwegian Sea, eastern North Atlantic marginal seas and Arctic gateways, and the Baltic Sea. The first evidence of possible biogeographical expansion of Pseudo-nitzschia taxa into frontier eastern Arctic gateways was provided from DNA barcoding signatures. Key climate change indicators, such as salinity, temperature, and water-column stratification were identified as drivers of upwelling and advection related to the distribution of regional Pseudo-nitzschia blooms. The possible influence of changing variables on bloom dynamics, magnitude, frequency and spatial and temporal distribution were interpreted in the context of regional ocean climate models. These climate change indicators may play key roles in selecting for the occurrence and diversity of Pseudo-nitzschia species within the broader microeukaryote communities. Shifts to higher temperature and lower salinity regimes predicted for the southern North Sea indicate the potential for high-magnitude Pseudo-nitzschia blooms, currently absent from this area. Ecological and socioeconomic impacts of Pseudo-nitzschia blooms are evaluated with reference to effects on fisheries and mariculture resources and coastal ecosystem function. Where feasible, effective adaptation strategies are proposed herein as emerging climate services for the northern CoCLiME region.

• Nam, Pham Viet; Hich, Tran Vy; Hoa, Nguyen van; Dinh, van Khuong; Minh, Nguyen Cong & Trung, Trang Si (2023). Additive biocomponents from catfish by-products enhance the growth of shrimp Litopenaeus vannamei. Fisheries and Aquatic Sciences (FAS). ISSN 2234-1749. 26(6), p. 367–379. doi: 10.47853/FAS.2023.e31. Full text in Research Archive Show summary

  The rapid expansion of shrimp production requires a huge amount of protein sources from soybeans and wild-caught fishmeal; both are becoming a shortage. Meanwhile, catfish production and processing is a giant industry in Vietnam, which produce hundred thousand tonnes of protein- and lipid-rich by-products, annually. Using catfish by-products to gradually replace the traditional protein sources in shrimp aquaculture may bring triple benefits: 1) reducing pressure on wild fish exploitation for fishmeal, 2) reducing the environmental impacts of catfish by-products, and 3) increasing the value and sustainability of aquaculture production. In this study, we used catfish by-products to produce fish protein hydrolysate (FPH) and nano-hydroxyapatite (HA) as additives in feed for Pacific white shrimp (Litopenaeus vannamei). The supplement mixture of FPH and HA was added into the commercial diet (Charoen Pokphand Group [CP], 38% protein, and 6.5% lipid) to reach 38%, 38.5%, 40%, 43%, and 44% of the crude protein content. The survival and growth of shrimps were weekly assessed to day 55. The results showed that the shrimp growth was highest at 43% crude protein content in the feed as indicated by an increase of 124% and 112% in shrimp weight and length, respectively, compared to the commercial reference diet. No negative effects of adding the mixture of FPH and HA on the water quality were observed. Vibrio density was lower than 6.5 × 103 CFU/mL, which is the lowest Vibrio density negatively affecting the shrimp growth and development. These findings indicate that the mixture of FPH and HA are promising additive components in feed for post-larval shrimp L. vannamei diets.

• Silva, Andreia Sofia Jorge; Kristiansen, Silje Marie; Sengupta, Sagnik; Gestel, Cornelis A. M. van; Leinaas, Hans Petter & Borgå, Katrine (2023). Using dietary exposure to determine sub-lethal effects from imidacloprid in two springtail (Collembola) species. Ecotoxicology. ISSN 0963-9292. 32, p. 1209–1220. doi: 10.1007/s10646-023-02715-x. Full text in Research Archive Show summary

  Abstract Standard toxicity tests expose springtails (Collembola) through soil, while dietary exposure tests with animals visible on a surface are less commonly applied. We refined a method for dietary chemical exposure for two widely distributed and abundant Collembola species: Folsomia quadrioculata and Hypogastrura viatica as existing methods were sub-optimal. Newly hatched Collembola were offered bark with a natural layer of Cyanobacteria that was either moistened with a solution of the neonicotinoid insecticide imidacloprid using a micropipette or soaked in the solution overnight. The first method was superior in producing a measured concentration close to the nominal (0.21 and 0.13 mg/kg dry bark, respectively), and resulting in sub-lethal effects as expected. The adult body size was reduced by 8% for both species, but egg production only in H. viatica . Contrastingly, soaked bark resulted in a measured concentration of 8 mg/kg dry bark, causing high mortality and no egg production in either species. Next, we identified the sub-lethal concentration-range by moistening the bark to expose H. viatica to 0, 0.01, 0.04, 0.13, 0.43 and 1.2 mg imidacloprid/kg dry bark. Only the highest concentration affected survival, causing a mortality of 77%. Imidacloprid reduced moulting rate and the body size at first reproduction. The age at first reproduction appeared delayed as some replicates did not reproduce within the experiment duration. The method of moistened bark for dietary exposure proved optimal to continuously study life history traits, such as growth and reproductive outcomes, which are important to understand effects on key events crucial for population viability and growth.

• Sengupta, Sagnik; Leinaas, Hans Petter; Gestel, Cornelis A.M. van; Jager, Tjalling; Rundberget, Thomas & Borgå, Katrine (2023). High sensitivity to dietary imidacloprid exposure in early life stages of Folsomia quadrioculata (Collembola) populations from contrasting climates. Agriculture, Ecosystems & Environment. Applied Soil Ecology. ISSN 0929-1393. 187. doi: 10.1016/j.apsoil.2023.104880. Full text in Research Archive Show summary

  Survival of early life stages is critical for population growth. Understanding the vulnerability of these sensitive stages can therefore improve ecological risk predictions. The globally-used neonicotinoid insecticide imidacloprid does not degrade easily in soil and occurs at concentrations potentially toxic to non-target soil organisms, such as Collembola. Here, we studied the effects of dietary exposure to imidacloprid on the survival of juveniles in an arctic and a temperate population of Folsomia quadrioculata (Collembola), a commonly-occurring litter-dwelling species in the Northern Hemisphere. The exposure lasted from <24 h to 30 days since hatching at 15 °C. We assessed whether (1) the arctic population of the test species with faster development rates could be more vulnerable than the temperate population, (2) cumulative mortality could increase substantially with exposure time, and (3) the mortality risk experienced during the juvenile stage could be greater than that experienced by the adults. We found a strong concentration-dependent decline in survival in both populations, with small but significantly different LC50s, despite large differences in multiple life-history traits. Applying a General Unified Threshold model for Survival (GUTS) showed a low threshold for effects, slow damage dynamics, a 6–11-fold decrease in LC50 from 14 to 30 days of exposure, and saturation of damage at the three highest concentrations. In addition, exposure starting soon after hatching caused much more mortality than that starting in the adult stages. Our findings suggest that toxicity tests not emphasizing the neonate stages or not lasting long enough can underestimate the implications for populations of naturally abundant non-target organisms.

• Haarr, Ane; Nipen, Maja; Mwakalapa, Eliezer Brown; Borgen, Anders; Mmochi, Aviti J. & Borgå, Katrine (2023). Chlorinated paraffins and dechloranes in free-range chicken eggs and soil around waste disposal sites in Tanzania. Chemosphere. ISSN 0045-6535. 329, p. 1–11. doi: 10.1016/j.chemosphere.2023.138646. Full text in Research Archive Show summary

  Electronic waste is a source of both legacy and emerging flame retardants to the environment, especially in regions where sufficient waste handling systems are lacking. In the present study, we quantified the occurrence of short- and medium chain chlorinated paraffins (SCCPs and MCCPs) and dechloranes in household chicken (Gallus domesticus) eggs and soil collected near waste disposal sites on Zanzibar and the Tanzanian mainland. Sampling locations included an e-waste facility and the active dumpsite of Dar es Salaam, a historical dumpsite in Dar es Salaam, and an informal dumpsite on Zanzibar. We compared concentrations and contaminant profiles between soil and eggs, as free-range chickens ingest a considerable amount of soil during foraging, with potential for maternal transfer to the eggs. We found no correlation between soil and egg concentrations or patterns of dechloranes or CPs. CPs with shorter chain lengths and higher chlorination degree were associated with soil, while longer chain lengths and lower chlorination degree were associated with eggs. MCCPs dominated the CP profile in eggs, with median concentrations ranging from 500 to 900 ng/g lipid weight (lw) among locations. SCCP concentrations in eggs ranged from below the detection limit (LOD) to 370 ng/g lw. Dechlorane Plus was the dominating dechlorane compound in all egg samples, with median concentrations ranging from 0.5 to 2.8 ng/g lw. SCCPs dominated in the soil samples (400–21300 ng/g soil organic matter, SOM), except at the official dumpsite where MCCPs were highest (65000 ng/g SOM). Concentrations of dechloranes in soil ranged from below LOD to 240 ng/g SOM, and the dominating compounds were Dechlorane Plus and Dechlorane 603. Risk assessment of CP levels gave margins of exposure (MOE) close to or below 1000 for SCCPs at one location.

• Bekkby, Trine; Torstensen, Ragnhild Ryther Grimm; Grünfeld, Lars Andreas Holm; Gundersen, Hege; Fredriksen, Stein & Rinde, Eli [Show all 12 contributors for this article] (2023). ‘Hanging gardens’—comparing fauna communities in kelp farms and wild kelp forests. Frontiers in Marine Science. 10. doi: 10.3389/fmars.2023.1066101. Full text in Research Archive Show summary

  A growing need for food is causing increased interest for seaweed farming globally. This requires knowledge of the industry’s effects on the marine environment. We therefore aimed to explore the communities hosted by a kelp farm compared to that of wild kelp forests. The study was performed in mid-western Norway. Kelp associated fauna were collected from farmed kelp (Saccharina latissima and Alaria esculenta), in wild kelp forests (S. latissima, A. esculenta and Laminaria hyperborea), and from fauna traps in the water column. The study showed that the kelp farm had lower taxa abundance and richness and a lower biodiversity than the wild kelp forests. Nonetheless, the farmed kelp hosted many associated species, with communities different from what was found on ropes without kelp (i.e., in the water column). The fauna communities among the farmed kelp were more similar to what was found in the wild L. hyperborea kelp forest than to its wild counterparts. The difference between the fauna communities of ‘old’ and ‘young’ farmed kelp (grown for 3 and 7 months, respectively) was not significant, but the fauna was dominated by the isopod species Idotea pelagica in the young forest and by amphipods, mainly belonging to the genus Caprella, in the older. The study contributes to our knowledge of kelp farms’ ecological role in the marine environment, which is of importance for today’s management as well as for ensuring a sustainable future development of the kelp farming industry.

• Broch, Catharina & Heuschele, Jan David (2023). Zoobooth: A portable, open-source and affordable approach for repeated size measurements of live individual zooplankton. Heliyon. 9(5). doi: 10.1016/j.heliyon.2023.e15383. Full text in Research Archive Show summary

  Repeated size measurements of individual animals are valuable data for many research questions, but it is often hard to obtain without causing stress or damage to the animal. We developed a video-based approach called Zoobooth to size individual zooplankton, which involves a low risk of handling accidents and stress. Here we describe the process of assembling the instrument we used to acquire video recordings of single zooplankton and the procedure to obtain size estimates from the recorded videos. Our setup produces accurate size estimates for Daphnia magna (correlation to manual measurements = 0.97), and was also tested with other zooplankton species. Zoobooth is especially advantageous when one needs size measurements of live, individual mesozooplankton. The device is small, portable, and comprised of very affordable and readily available components. It can easily be modified for other purposes, such as studies of coloration or behavior of micro-and macro-plankton. We share all the files to build and use Zoobooth.

• Buttay, Lucie; Ohlberger, Jan Philipp & Langangen, Øystein Ole Gahr (2023). Management strategies can buffer the effect of mass mortality in early life stages of fish. Journal of Applied Ecology. ISSN 0021-8901. 60(10), p. 2056–2065. doi: 10.1111/1365-2664.14489. Full text in Research Archive Show summary

  1. Mass mortality (MM) events affecting early life stages of fish can have strong and long-term consequences for population abundance and demography as well as the economic activity supported by exploited stocks. Adaptive fishery manage-ment may help mitigate economic impacts and ensure sustainable resource use following a MM event. 2. Using a state-space life cycle model, we simulated ‘what-if’ scenarios of MM on Northeast Arctic cod (Gadus morhua) eggs and larvae. We compared the expected catches, total stock biomass (TSB), and interannual variability in catches over a period of 10 years after the simulated disturbance. We further evaluated a range of management mitigation strategies, namely reductions in fishing mortality of varying duration (1–10 years) and intensity (no fishing reduction to full ban). 3. A large range of reductions in fishing led to an increase in expected catches over 10 years compared to no reductions, especially when applied immediately after the perturbation and when the cod population was characterized by a high mean age and high TSB. Severe fishing reductions can increase catches substantially but are associated with high interannual variability. Fishing reductions of moder-ate intensity applied between 1 and 4 years would allow to increase catches with only a slight increase in interannual variability. 4. Our findings demonstrate the potential benefits of an adaptive approach to fish-eries management and highlight that mitigation actions may ensure the sustain-able exploitation of fish stocks in the wake of unexpected disturbances. 5. Synthesis and application. Mass mortality events during early life stages of fish can potentially have substantial and long-term effects on the population. Mitigation is more efficient when the affected population has a diverse age structure and when the mitigation strategy is applied immediately after the perturbation. Severe re-duction in fishing mortality is an efficient measure to increase the expected aver-age catch but is associated with high interannual variability. Fishing reduction of moderate intensity applied during 1–4 years after the event also increases the expected average catch with only slightly higher interannual variability in catches.

• Gerland, Sebastian; Ingvaldsen, Randi Brunvær; Reigstad, Marit; Sundfjord, Arild; Bogstad, Bjarte & Chierici, Melissa [Show all 41 contributors for this article] (2023). Still Arctic? — The changing Barents Sea. Elementa: Science of the Anthropocene. 11(1), p. 1–62. doi: 10.1525/elementa.2022.00088. Full text in Research Archive Show summary

  The Barents Sea is one of the Polar regions where current climate and ecosystem change is most pronounced. Here we review the current state of knowledge of the physical, chemical and biological systems in the Barents Sea. Physical conditions in this area are characterized by large seasonal contrasts between partial sea-ice cover in winter and spring versus predominantly open water in summer and autumn. Observations over recent decades show that surface air and ocean temperatures have increased, sea-ice extent has decreased, ocean stratification has weakened, and water chemistry and ecosystem components have changed, the latter in a direction often described as “Atlantification” or “borealisation,” with a less “Arctic” appearance. Temporal and spatial changes in the Barents Sea have a wider relevance, both in the context of large-scale climatic (air, water mass and sea-ice) transport processes and in comparison to other Arctic regions. These observed changes also have socioeconomic consequences, including for fisheries and other human activities. While several of the ongoing changes are monitored and quantified, observation and knowledge gaps remain, especially for winter months when field observations and sample collections are still sparse. Knowledge of the interplay of physical and biogeochemical drivers and ecosystem responses, including complex feedback processes, needs further development.

• Bachmann, Lutz; Beermann, Jan; Brey, Thomas; Boer, Hugo de; Dannheim, Jennifer & Edvardsen, Bente [Show all 20 contributors for this article] (2023). The role of systematics for understanding ecosystem functions: Proceedings of the Zoologica Scripta Symposium, Oslo, Norway, 25 August 2022. Zoologica Scripta. ISSN 0300-3256. 52(3), p. 187–214. doi: 10.1111/zsc.12593. Full text in Research Archive Show summary

  Abstract On 25 August 2022, the Zoologica Scripta ‐ An International Journal of Systematic Zoology and the Norwegian Academy of Sciences and Letters arranged a symposium entitled ‘The role of systematics for understanding ecosystem functions’ in the Academy's premises in Oslo, Norway. The symposium aimed at offering a forum for exploring and discussing trends and future developments in the field of systematics. Eleven international experts contributed expertise on various issues related to global challenges, such as biodiversity assessments, databases, cutting‐edge analysis tools, and the consequences of the taxonomic impediment. Here, we compiled a multi‐author proceedings paper of the symposium contributions that are arranged in chapters and presents the content and the key conclusions of the majority of the presentations.

• Opdal, Anders Martin Frugård; Andersen, Tom; Hessen, Dag Olav; Lindemann, Christian & Aksnes, Dag Lorents (2023). Tracking freshwater browning and coastal water darkening from boreal forests to the Arctic Ocean. Limnology and Oceanography Letters. 8(4), p. 611–619. doi: 10.1002/lol2.10320. Full text in Research Archive Show summary

  The forest cover of Northern Europe has been steadily expanding during the last 120 years. More terrestrial vegetation and carbon fixation leads to more export to surface waters. This may cause freshwater browning, as more degraded plant-litter ends up as chromophoric (colored) dissolved organic matter. Although most freshwater ultimately drains to coastal waters, the link between freshwater browning and coastal water darkening is poorly understood. Here, we explore this relationship through a combination of centennial records of forest cover and coastal water clarity, contemporary optical measurements in lakes and coastal waters, as well as an ocean drift model. We suggest a link between forest cover in Northern Europe and coastal water clarity in the Baltic, Kattegat, and Skagerrak Sea and show how brown-colored freshwater from Northern European catchments can dictate coastal water clarity across thousands of kilometers, from the Baltic lakes to the Barents Sea.

• Zheng, Xiaoqi; Lu, Yonglong; Ma, Cuimei; Yuan, Jingjing; Stenseth, Nils Christian & Hessen, Dag Olav [Show all 10 contributors for this article] (2023). Greenhouse gas emissions from extractive industries in a globalized era. Journal of Environmental Management (JEM). ISSN 0301-4797. 343, p. 1–10. doi: 10.1016/j.jenvman.2023.118172. Full text in Research Archive
• Kohlbach, Doreen; Goraguer, Lucie; Bodur, Yasemin V.; Müller, Oliver; Arumí, Martí Amargant & Blix, Katalin [Show all 23 contributors for this article] (2023). Earlier sea-ice melt extends the oligotrophic summer period in the Barents Sea with low algal biomass and associated low vertical flux. Progress in Oceanography. ISSN 0079-6611. 213. doi: 10.1016/j.pocean.2023.103018. Full text in Research Archive Show summary

  The decrease in Arctic sea-ice extent and thickness as a result of global warming will impact the timing, duration, magnitude and composition of phytoplankton production with cascading effects on Arctic marine food-webs and biogeochemical cycles. Here, we elucidate the environmental drivers shaping the composition, abundance, biomass, trophic state and vertical flux of protists (unicellular eukaryotes), including phytoplankton, in the Barents Sea in late August 2018 and 2019. The two years were characterized by contrasting sea-ice conditions. In August 2018, the sea-ice edge had retreated well beyond the shelf break into the Nansen Basin (>82◦N), while in 2019, extensive areas of the northwestern Barents Sea shelf (>79◦N) were still ice-covered. These contrasting sea-ice conditions resulted in marked interannual differences in the pelagic protist community structure in this area. In August 2018, the protist community was in a post-bloom stage of seasonal succession characterized by oligotrophic surface waters and dominance of small-sized phytoplankton and heterotrophic protists (predominantly flagellates and ciliates) at most stations. In 2019, a higher contribution of autotrophs and large-celled phytoplankton, particularly diatoms, to total protist biomass compared to 2018 was reflected in higher chlorophyll a concentrations and suggested that the protist community was still in a late bloom stage at some stations. It is noteworthy that particularly diatoms contributed a considerably higher proportion to the protist biomass at the ice-covered stations in both years compared to the open-water stations. This pattern was also evident in the higher vertical protist biomass flux in 2019, dominated by dinoflagellates and diatoms, compared to 2018. Our results suggest that the predicted transition toward an ice-free Barents Sea will lengthen the oligotrophic summer period with low algal biomass and associated low vertical flux.

• Paus-Knudsen, Julie Sørlie; Sveinsson, Henrik Andersen; Grung, Merete; Borgå, Katrine & Nielsen, Anders (2023). The Neonicotinoid Imidacloprid Impairs Learning, Locomotor Activity Levels, and Sucrose Solution Consumption in Bumblebees (Bombus terrestris). Environmental Toxicology and Chemistry. ISSN 0730-7268. 42(6), p. 1337–1345. doi: 10.1002/etc.5611. Full text in Research Archive Show summary

  Bumblebees carry out the complex task of foraging to provide for their colonies. They also conduct pollination, an ecosystem service of high importance to both wild plants and entomophilous crops. Insecticides can alter different aspects of bumblebee foraging behavior, including the motivation to leave the hive, finding the right flowers, handling flowers, and the ability to return to the colony. In the present study, we assessed how the neonicotinoid imidacloprid affects bumblebees' foraging behavior after exposure to four different treatment levels, including field-realistic concentrations (0 [control], 1, 10, and 100 μg/L), through sucrose solution over 9 days. We observed the behavior of several free-flying bumblebees simultaneously foraging on artificial flowers in a flight arena to register the bees' complex behavior postexposure. To conduct a detailed assessment of how insecticides affect bumblebee locomotor behavior, we used video cameras and analyzed the recordings using computer vision. We found that imidacloprid impaired learning and locomotor activity level when the bumblebees foraged on artificial flowers. We also found that imidacloprid exposure reduced sucrose solution intake and storage. By using automated analyses of video recordings of bumblebee behavior, we identified sublethal effects of imidacloprid exposure at field-realistic doses. Specifically, we observed negative impacts on consumption of sucrose solution as well as on learning and locomotor activity level. Our results highlight the need for more multimodal approaches when assessing the sublethal effects of insecticides and plant protection products in general.

• Matek, Antonija; Bosak, Sunčica; Supraha, Luka; Neeley, Aimee; Višić, Hrvoje & Cetinić, Ivona [Show all 7 contributors for this article] (2023). Phytoplankton diversity and chemotaxonomy in contrasting North Pacific ecosystems. PeerJ. 11, p. 1–30. doi: 10.7717/peerj.14501. Full text in Research Archive Show summary

  Background Phytoplankton is the base of majority of ocean ecosystems. It is responsible for half of the global primary production, and different phytoplankton taxa have a unique role in global biogeochemical cycles. In addition, phytoplankton abundance and diversity are highly susceptible to climate induced changes, hence monitoring of phytoplankton and its diversity is important and necessary. Methods Water samples for phytoplankton and photosynthetic pigment analyses were collected in boreal winter 2017, along transect in the North Pacific Subtropical Gyre (NPSG) and the California Current System (CCS). Phytoplankton community was analyzed using light and scanning electron microscopy and photosynthetic pigments by high-performance liquid chromatography. To describe distinct ecosystems, monthly average satellite data of MODIS Aqua Sea Surface temperature and Chlorophyll a concentration, as well as Apparent Visible Wavelength were used. Results A total of 207 taxa have been determined, mostly comprised of coccolithophores (35.5%), diatoms (25.2%) and dinoflagellates (19.5%) while cryptophytes, phytoflagellates and silicoflagellates were included in the group “others” (19.8%). Phytoplankton spatial distribution was distinct, indicating variable planktonic dispersal rates and specific adaptation to ecosystems. Dinoflagellates, and nano-scale coccolithophores dominated NPSG, while micro-scale diatoms, and cryptophytes prevailed in CCS. A clear split between CCS and NPSG is evident in dendogram visualising LINKTREE constrained binary divisive clustering analysis done on phytoplankton counts and pigment concentrations. Of all pigments determined, alloxanthin, zeaxanthin, divinyl chlorophyll b and lutein have highest correlation to phytoplankton counts. Conclusion Combining chemotaxonomy and microscopy is an optimal method to determine phytoplankton diversity on a large-scale transect. Distinct communities between the two contrasting ecosystems of North Pacific reveal phytoplankton groups specific adaptations to trophic state, and support the hypothesis of shift from micro- to nano-scale taxa due to sea surface temperatures rising, favoring stratification and oligotrophic conditions.

• Holme, Jørn Andreas; Vondráček, Jan; Machala, Miroslav; Lagadic-Gossmann, Dominique; Vogel, Christoph F.A & Ferrec, Eric Le [Show all 8 contributors for this article] (2023). Lung cancer associated with combustion particles and fine particulate matter (PM2.5) - The roles of polycyclic aromatic hydrocarbons (PAHs) and the aryl hydrocarbon receptor (AhR). Biochemical Pharmacology. ISSN 0006-2952. 216. doi: 10.1016/j.bcp.2023.115801. Full text in Research Archive Show summary

  Air pollution is the leading cause of lung cancer after tobacco smoking, contributing to 20% of all lung cancer deaths. Increased risk associated with living near trafficked roads, occupational exposure to diesel exhaust, indoor coal combustion and cigarette smoking, suggest that combustion components in ambient fine particulate matter (PM2.5), such as polycyclic aromatic hydrocarbons (PAHs), may be central drivers of lung cancer. Activation of the aryl hydrocarbon receptor (AhR) induces expression of xenobiotic-metabolizing enzymes (XMEs) and increase PAH metabolism, formation of reactive metabolites, oxidative stress, DNA damage and mutagenesis. Lung cancer tissues from smokers and workers exposed to high combustion PM levels contain mutagenic signatures derived from PAHs. However, recent findings suggest that ambient air PM2.5 exposure primarily induces lung cancer development through tumor promotion of cells harboring naturally acquired oncogenic mutations, thus lacking typical PAH-induced mutations. On this background, we discuss the role of AhR and PAHs in lung cancer development caused by air pollution focusing on the tumor promoting properties including metabolism, immune system, cell proliferation and survival, tumor microenvironment, cell-to-cell communication, tumor growth and metastasis. We suggest that the dichotomy in lung cancer patterns observed between smoking and outdoor air PM2.5 represent the two ends of a dose–response continuum of combustion PM exposure, where tumor promotion in the peripheral lung appears to be the driving factor at the relatively low-dose exposures from ambient air PM2.5, whereas genotoxicity in the central airways becomes increasingly more important at the higher combustion PM levels encountered through smoking and occupational exposure.

• Cui, Haotian; Lu, Yonglong; Zhou, Yunqiao; He, Guizhen; Song, Shuai & Yang, Shengjie [Show all 15 contributors for this article] (2023). Carbon flow through continental-scale ground logistics transportation. iScience. 26(1), p. 1–18. doi: 10.1016/j.isci.2022.105792. Full text in Research Archive Show summary

  The flourishing logistics in both developed and emerging economies leads to huge greenhouse gas (GHG) emissions; however, the emission fluxes are poorly constrained. Here, we constructed a spatial network of logistic GHG emissions based on multisource big data at continental scale. GHG emissions related to logistics transportation reached 112.14 Mt CO2-equivalents (CO2e), with seven major urban agglomerations contributing 63% of the total emissions. Regions with short transport distances and well-developed road infrastructure had relatively high emission efficiency. Underlying value flow of the commodities is accompanied by logistics carbon flow along the supply chain. The main driving factors affecting GHG emissions are driving speed and gross domestic product. It may mitigate GHG emissions by 27.50–1162.75 Mt CO2e in 15 years if a variety of energy combinations or the appropriate driving speed (65–70 km/h) is adopted. The estimations are of great significance to make integrated management policies for the global logistics sector.

• Heuschele, Jan David; Andersen, Tom; Walseng, Bjørn & Hessen, Dag Olav (2023). Assessing climatic and spatial variables influencing zooplankton richness for space-for-time predictions. Freshwater Biology. ISSN 0046-5070. 69(1), p. 64–73. doi: 10.1111/fwb.14193. Full text in Research Archive Show summary

  1. The macroecological drivers of freshwater diversity are accredited geographical, spatial and climatic variables, but also to productivity, ecosystem age and landscape history. Locally diversity is also influenced by the dispersal ability of species. Here we evaluated how spatial and climatic variables influence species richness and macroecological patterns in Cladocera and Copepoda. We also discuss whether a space-for-time approach is suitable to predict the community's response to the current rapid warming of lakes. 2. We use the presence-absence of pelagic and littoral microcrustaceans in 1465 Norwegian lakes with a wide range of latitudinal, longitudinal, and altitudinal gradients, as well as a wide span in lake areas, to evaluate how spatial and climatic factors influence zooplankton diversity in two major groups: Cladocera and Copepoda. 3. Longitude and latitude per se were poor predictors of zooplankton richness, but a combination of spatial and ecological predictors gave a good spatial prediction of cladoceran and copepod richness. These two groups did, however, not differ in their spatial distribution, with a strikingly fixed proportion of copepods close to 0.3, suggesting no obvious Allee- effects regarding the mode of reproduction (asexual vs sexual). 4. Since temperature alone was a poor predictor of species richness for both groups and dispersal constraints can make it very difficult to estimate a new richness equilibrium under a future climate, space-for-time predictions may have limited value for assessing future patterns of microcrustacean diversity. 5. Based on a quite unique dataset in terms of the sheer number of sites, spatial gradients, and inclusion of littoral species, our study demonstrates that assessments on how changing climate will shape and modulate zooplankton communities in the future are problematic. biogeography, dispersal, diversity, lakes, micro-crustaceans

• Andvik, Clare Margaret; Haug, Tore; Lyche, Jan Ludvig & Borgå, Katrine (2023). Emerging and legacy contaminants in common minke whale from the Barents sea. Environmental Pollution. ISSN 1566-0745. 319. doi: 10.1016/j.envpol.2023.121001. Full text in Research Archive Show summary

  Persistent organic pollutants (POPs), including brominated flame retardants (BFRs), perfluoroalkyl substances (PFAS) and metals, can accumulate in marine mammals and be transferred to offspring. In this study, we analyzed 64 lipophilic POPs, including four emerging BFRs, in the blubber, liver and muscle of 17 adult common minke whales (Balaenoptera acutorostrata) from the Barents Sea to investigate occurrence and tissue partitioning. In addition, the placental transfer concentration ratios of 14 PFAS and 17 metals were quantified in the muscle of nine female-fetus pairs to investigate placental transfer. Legacy lipophilic POPs were the dominating compound group in every tissue, and we observed generally lower levels compared to previous studies from 1992 to 2001. We detected the emerging BFRs hexabromobenzene (HBB) and pentabromotoluene (PBT), but in low levels compared to the legacy POPs. We detected nine PFAS, and levels of perfluorooctane sulfonate (PFOS) were higher than detected from the same population in 2011, whilst levels of Hg were comparable to 2011. Levels of lipophilic contaminants were higher in blubber compared to muscle and liver on both a wet weight and lipid adjusted basis, but tissue partitioning of the emerging BFRs could not be determined due to the high number of samples below the limit of detection. The highest muscle ΣPFAS levels were quantified in fetuses (23 ± 8.7 ng/g ww), followed by adult males (7.2 ± 2.0 ng/gg ww) and adult females (4.5 ± 1.1 ng/g ww), showing substantial placental transfer from mother to fetus. In contrast, Hg levels in the fetus were lower than the mother. Levels were under thresholds for risk of health effects in the whales. This study is the first to report occurrence and placental transfer of emerging contaminants in common minke whales from the Barents Sea, contributing valuable new data on pollutant levels in Arctic wildlife.

• Eriksen, Elke; Madsen, Anne Mette; Afanou, Komlavi Anani; Straumfors, Anne; Eiler, Alexander & Graff, Pål (2023). Occupational exposure to inhalable pathogenic microorganisms in waste sorting. International Journal of Hygiene and Environmental Health. ISSN 1438-4639. 253. doi: 10.1016/j.ijheh.2023.114240. Full text in Research Archive Show summary

  This study assessed microorganisms in personal inhalable work air samples aiming to identify potential human pathogens, and correlate exposure to adverse health outcomes in waste workers. Full-shift personal exposure was measured in six different waste sorting plants. Microbial concentrations in inhalable air samples were analysed using MALDI-TOF MS for cultivable, and next generation sequencing (NGS) for non-cultivable microorganisms. Concentrations of bacterial and fungal CFUs varied substantially within and between waste sorting plants, ranging from no identifiable organisms to a maximum concentration in the order of 105 CFU/m3. Bacillus and Staphylococcus were among the most abundant bacterial genera, whilst fungal genera were dominated by Aspergillus and Penicillium. Approximately 15% of all identified species were human pathogens classified in risk group 2, whereas 7% belonged to risk group 1. Furthermore, significant correlations between concentrations of fungi in risk group 1 and self-reported adverse symptoms, such as wheezing were identified in exposed workers. The combination of culture-based methods and NGS facilitated the investigation of infectious microbial species with potential pathophysiological properties as well as non-infectious biological agents in inhalable work air samples and thereby contributed to the risk assessment of occupational exposure in waste sorting.

• Fontaine, Laurent; Pin, Lorenzo; Savio, Domenico; Friberg, Nikolai; Kirschner, Alexander K. T. & Farnleitner, Andreas H. [Show all 7 contributors for this article] (2023). Bacterial bioindicators enable biological status classification along the continental Danube river. Communications Biology. 6. doi: 10.1038/s42003-023-05237-8. Full text in Research Archive Show summary

  Despite the importance of bacteria in aquatic ecosystems and their predictable diversity patterns across space and time, biomonitoring tools for status assessment relying on these organisms are widely lacking. This is partly due to insufficient data and models to identify reliable microbial predictors. Here, we show metabarcoding in combination with multivariate statistics and machine learning allows to identify bacterial bioindicators for existing biological status classification systems. Bacterial beta-diversity dynamics follow environmental gradients and the observed associations highlight potential bioindicators for ecological outcomes. Spatio-temporal links spanning the microbial communities along the river allow accurate prediction of downstream biological status from upstream information. Network analysis on amplicon sequence veariants identify as good indicators genera Fluviicola, Acinetobacter, Flavobacterium, and Rhodoluna, and reveal informational redundancy among taxa, which coincides with taxonomic relatedness. The redundancy among bacterial bioindicators reveals mutually exclusive taxa, which allow accurate biological status modeling using as few as 2–3 amplicon sequence variants. As such our models show that using a few bacterial amplicon sequence variants from globally distributed genera allows for biological status assessment along river systems.

• Skjæraasen, Jon Egil; Karlsen, Ørjan; Langangen, Øystein Ole Gahr; Meier, Sonnich; Dunlop, Katherine Mary & Meeren, Terje van der [Show all 14 contributors for this article] (2022). Attraction of cod Gadus morhua from coastal spawning grounds to salmon farms. Aquaculture Environment Interactions. ISSN 1869-215X. 14, p. 229–242. doi: 10.3354/aei00440. Full text in Research Archive Show summary

  Wild fish aggregate at aquaculture net-pens, but the underlying mechanisms are not fully understood. This study examined how salmon farms attract coastal Atlantic cod Gadus morhua from their inshore spawning grounds. Acoustic receivers were deployed at 5 known cod spawning grounds and 6 salmon Salmo salar farms located at varying distances from these grounds in a mid-Norway study site. Cod were caught at each spawning ground annually from 2017-2019, fitted with acoustic transmitters and released (n = 535). A total of 289 tagged cod (54%) were detected at the salmon farms, with more cod detected at farms closest to the focal spawning grounds and at operational farms. The latter result is likely linked to the availability of feeding opportunities at farm locations. Those cod that were detected by the receivers spent less time at farms farther from their release locations. For the farm-associated cod, 70% were detected for <1 wk at the farms. However, 48 cod spent >1 mo close to the farms, with 1 individual staying 720 d underneath the farm. A total of 135 cod visited 2 or more farms, with farms in proximity more connected in terms of inter-farm movement. Some of the cod utilizing these local spawning grounds likely have considerable dietary input from salmon feed.

• Le, Minh Hoang; Dinh, van Khuong; Vo, Xuan Thi & Pham, Hung Quoc (2022). Direct and delayed synergistic effects of extreme temperature, metals and food limitation on tropical reef-associated fish juveniles. Estuarine, Coastal and Shelf Science. ISSN 0272-7714. 278. doi: 10.1016/j.ecss.2022.108108. Full text in Research Archive
• Dinh, van Khuong; Konestabo, Heidi Sjursen; Borgå, Katrine; Hylland, Ketil; Macaulay, Samuel J. & Jackson, Michelle C [Show all 8 contributors for this article] (2022). Interactive Effects of Warming and Pollutants on Marine and Freshwater Invertebrates. Current Pollution Reports. 8, p. 341–359. doi: 10.1007/s40726-022-00245-4. Full text in Research Archive Show summary

  Abstract Purpose of Review Global warming and pollution are among the five major causes of global biodiversity loss, particularly in aquatic invertebrates which are highly diverse but understudied. In this review, we highlight advancements in current environmental studies investigating the interactive effects between warming and contaminants in freshwater and marine invertebrates. We not only focused on temperate regions but also synthesized information on the less studied Arctic/Antarctic and tropical regions. Recent Findings In general, the same combination of warming and contaminants may result in either additive or non-additive interactive effects depending on taxa, the response variable, life stage, genotype, exposure level, duration and order of exposure, and the number of exposed generations. For traditional contaminants such as metals and pesticides, combined effects with warming at the individual level were generally synergistic. Growing evidence suggests that multigenerational exposure can shift the interaction between warming and contaminants toward antagonism, while contemporary evolution may change the interaction type. Summary Our synthesis highlights the importance of temporal aspects in shaping interaction type, including order of exposure, ontogenetic effects, transgenerational effects, and evolution. The combination of laboratory experiments (to advance mechanistic understanding) and outdoor mesocosm studies or field observations (to increase realism) is needed to obtain comprehensive assessments of interactive effects of warming and pollutants from genes to ecosystems.

• Dupont, Nicolas; Vikebø, Frode Bendiksen & Langangen, Øystein Ole Gahr (2022). Assessing the patchiness of early life stage of a fish stock (Gadus morhua) and its contribution to the stock recruitment. Frontiers in Marine Science. 9, p. 1–10. doi: 10.3389/fmars.2022.932169. Full text in Research Archive Show summary

  Patchiness, defined as spatial heterogeneity in distribution of organisms, is a common phenomenon in zooplankton including ichtyoplankton. In heterogeneous landscapes, depending on the scale of prey and predatory distributions, individuals in patches may experience distinct differences in the survival rate compared to individuals distributed more homogeneously outside patches. In this study, we focused on drifting eggs and larvae of Northeast Arctic (NEA) cod, one of the largest exploited fish stock in the world. The eggs and larvae are largely distributed along the north-western coast of Norway and northern Russia. We ask to what degree individuals are located in patches contribute to the species recruitment. For this purpose, we developed a patch recognition method to detect the existence of patches in particle tracking simulations using a connected-component labeling algorithm. We then assessed the contribution of individuals in detected patches to the total recruitment. Our results showed that depending on year, day of year, and resolution scale for detection of patches, recruits present in patches can vary between 0.6% and 38.7% with an average of 20.4% of total recruitment. The percentage decreased with increasing day of year in the drifting season but increased with decreasing patch resolution scale, down to the finest investigated scale of 8 km. On the basis of these results, we advise field recruitment studies of NEA cod to at least resolve an 8-km spatial scale to capture effects of spatial heterogeneity in the survival rate on the species recruitment.

• Christiansen, Svenja; Langangen, Øystein Ole Gahr; Titelman, Josefin; Vøllestad, Leif Asbjørn & Kaartvedt, Stein (2022). Three-dimensional swimming behavior and activity of a mesopelagic fish. Limnology and Oceanography. ISSN 0024-3590. 67, p. 2677–2690. doi: 10.1002/lno.12230. Full text in Research Archive Show summary

  Knowledge of the three-dimensional behavior and activity patterns of mesopelagic fishes is crucial for understanding their role in ecological and biogeochemical processes in the ocean. We here show that the use of submerged stationary echosounders enables detailed analysis of three-dimensional swimming behavior of small mesopelagic fishes in situ. We explore a 4-month continuous dataset containing more than 100,000 nocturnal tracks of juvenile Maurolicus muelleri, obtained from a surface-facing, moored echosounder in a Norwegian fjord. We extend previous observations of vertical nocturnal swimming and step-wise (stop-and-go) dusk and dawn migrations with the corresponding horizontal and turning behavior. In the middle of the night, the M. muelleri mainly drifted with the currents. Horizontal swimming speeds were then usually below 0.5 body length s−1 but increased substantially during the step-wise dusk and dawn vertical migration. Most vertical relocations were followed by a change in horizontal direction. Our observations are in line with hypotheses of growth maximization in the juvenile fish, and of reducing detection and encounters with predators.

• Guðmundsson, Guðmundur; Cedhagen, Tomas & Andersen, Tom (2022). Taxonomy and distribution of recent species of the subfamily Nodosariinae (Foraminifera) in Icelandic waters. European Journal of Taxonomy. 824, p. 1–74. doi: 10.5852/ejt.2022.824.1827. Full text in Research Archive Show summary

  Taxonomy of fourteen very little known species of Nodosariinae Ehrenberg, 1838 in Icelandic waters is revised. Knowledge of these species in the North Atlantic relies mainly on studies in the late 19th and early 20th centuries, using large volume samplers. Later studies have emphasized quantitative samples of a few cm3 where the Nodosariinae are very rare. This study analysed 879 dredging samples where Nodosariinae occurred in 492 samples, comprising 7598 specimens of about 415 000 of all picked foraminifera. Ordination analysis of species distributions reflects prominent temperature and salinity differences that exist in the sampling area (753 000 km2) north and south of the Greenland-Scotland Ridge (GSR). Eight species are restricted to southern temperate waters (&gt; 2°C): Dentalina mutabilis (Costa, 1855), Dentalina antarctica Parr, 1950, Dentalina antennula d’Orbigny, 1846, Dentalina filiformis (d’Orbigny, 1826), Grigelis pyrula (d’Orbigny, 1826), Grigelis guttifera (d’Orbigny, 1846) comb. nov., Grigelis semirugosus ? (d’Orbigny, 1846) and Nodosaria subsoluta Cushman, 1923. Four species (Nodosaria haliensis Eiland &amp;#38; Guðmundsson, 2004, Nodosaria incerta Neugeboren, 1856, Dentalina elegans d’Orbigny, 1846 and Dentalina frobisherensis Loeblich &amp;#38; Tappan, 1953) occur mainly north of Iceland. Two species, Dentalina obliqua (Linnaeus,1758) and Pseudonodosaria subannulata (Cushman, 1923), have wide tolerance ranges for physical variables.

• Šigutová, Hana; Dolný, Aleš; Samways, Michael J.; Hardersen, Sönke; Junior, José Max Barbosa Oliveira & Juen, Leandro [Show all 8 contributors for this article] (2022). Odonata as indicators of pollution, habitat quality, and landscape disturbance. In Córdoba-Aguilar, Alex; Beatty, Christopher & Bried, Jason T. (Ed.), Dragonflies and Damselflies: Model Organisms for Ecological and Evolutionary Research. Oxford University Press. ISSN 9780192898623. p. 371–384. doi: 10.1093/oso/9780192898623.003.0026. Full text in Research Archive
• Keilen, Ellen Kristine; Borgå, Katrine; Thorstensen, Helene Skjeie; Hylland, Ketil; Helberg, Morten & Warner, Nicholas Alexander [Show all 9 contributors for this article] (2022). Differences in Trophic Level, Contaminant Load, and DNA Damage in an Urban and a Remote Herring Gull (Larus argentatus) Breeding Colony in Coastal Norway. Environmental Toxicology and Chemistry. ISSN 0730-7268. 41(10), p. 2466–2478. doi: 10.1002/etc.5441. Full text in Research Archive Show summary

  Herring gulls (Larus argentatus) are opportunistic feeders, resulting in contaminant exposure depending on area and habitat. We compared contaminant concentrations and dietary markers between two herring gull breeding colonies with different distances to extensive human activity and presumed contaminant exposure from the local marine diet. Furthermore, we investigated the integrity of DNA in white blood cells and sensitivity to oxidative stress. We analyzed blood from 15 herring gulls from each colony—the urban Oslofjord near the Norwegian capital Oslo in the temperate region and the remote Hornøya island in northern Norway, on the Barents Sea coast. Based on d13C and d34S, the dietary sources of urban gulls differed, with some individuals having a marine and others a more terrestrial dietary signal. All remote gulls had a marine dietary signal and higher relative trophic level than the urban marine feeding gulls. Concentrations (mean ± standard deviation [SD]) of most persistent organic pollutants, such as polychlorinated biphenyl ethers (PCBs) and perfluorooctane sulfonic acid (PFOS), were higher in urban marine (PCB153 17 ± 17 ng/g wet weight, PFOS 25 ± 21 ng/g wet wt) than urban terrestrial feeders (PCB153 3.7 ± 2.4 ng/g wet wt, PFOS 6.7 ± 10 ng/g wet wt). Despite feeding at a higher trophic level (d15N), the remote gulls (PCB153 17 ± 1221 ng/g wet wt, PFOS 19 ± 1421 ng/g wet wt) were similar to the urban marine feeders. Cyclic volatile methyl siloxanes were detected in only a few gulls, except for decamethylcyclopentasiloxane in the urban colony, which was found in 12 of 13 gulls. Only hexachlorobenzene was present in higher concentrations in the remote (2.6 ± 0.42 ng/g wet wt) compared with the urban colony (0.34 ± 0.33 ng/g wet wt). Baseline and induced DNA damage (doublestreak breaks) was higher in urban than in remote gulls for both terrestrial and marine feeders.

• Parra, Nicolas Valiente; Eiler, Alexander; Allesson, Lina; Andersen, Tom; Clayer, Francois & Crapart, Camille Marie [Show all 13 contributors for this article] (2022). Catchment properties as predictors of greenhouse gas concentrations across a gradient of boreal lakes. Frontiers in Environmental Science. 10. doi: 10.3389/fenvs.2022.880619. Full text in Research Archive Show summary

  Boreal lakes are the most abundant lakes on Earth. Changes in acid rain deposition, climate, and catchment land use have increased lateral fluxes of terrestrial dissolved organic matter (DOM), resulting in a widespread browning of boreal freshwaters. This browning affects the aqueous communities and ecosystem processes, and boost emissions of the greenhouse gases (GHG) CH 4 , CO 2 , and N 2 O. In this study, we predicted biotic saturation of GHGs in boreal lakes by using a set of chemical, hydrological, climate, and land use parameters. For this purpose, concentrations of GHGs and nutrients (organic C, -P, and -N) were determined in surface water samples from 73 lakes in south-eastern Norway covering wide ranges in DOM and nutrient concentrations, as well as catchment properties and land use. The spatial variation in saturation of each GHG is related to explanatory variables. Catchment characteristics (hydrological and climate parameters) such as lake size and summer precipitation, as well as NDVI, were key determinants when fitting GAM models for CH 4 and CO 2 saturation (explaining 71 and 54%, respectively), while summer precipitation and land use data were the best predictors for the N 2 O saturation, explaining almost 50% of deviance. Our results suggest that lake size, precipitation, and terrestrial primary production in the watershed control the saturation of GHG in boreal lakes. These predictions based on the 73-lake dataset was validated against an independent dataset from 46 lakes in the same region. Together, this provides an improved understanding of drivers and spatial variation in GHG saturation in boreal lakes across wide gradients of lake and catchment properties. The assessment highlights the need to incorporate multiple explanatory parameters in prediction models of GHGs for extrapolation across the boreal biome.

• Dierkes, Jutta; Dietrich, Stefan; Abraham, Klaus; Monien, Bernhard H.; McCann, Adrian & Borgå, Katrine [Show all 7 contributors for this article] (2022). Stable isotope ratios of nitrogen and carbon as biomarkers of a vegan diet. European Journal of Nutrition. ISSN 1436-6207. p. 1–9. doi: 10.1007/s00394-022-02992-y. Full text in Research Archive Show summary

  Purpose Dietary biomarkers can potentially overcome the limitations of self-reported dietary data. While in ecology and archaeology, stable isotope ratios of carbon and nitrogen are widely used as biomarkers, this is not the case in nutrition research. Since the abundance of the 13C and the 15N isotope differ in food sources from plant and animal origin, stable isotope ratios of carbon and nitrogen (δ13C and δ15N) may differ in human biological material. Here, we investigated the stable isotope ratios of nitrogen and carbon in serum and urine from vegans and omnivores. Method Measurement of δ15N and δ13C in serum and 24 h urine was performed by Elemental Analyzer–Isotope Ratio Mass Spectrometer in the cross-sectional study “Risks and Benefits of a Vegan Diet”. The study included 36 vegans and 36 omnivores with a median age of 37.5 years (matched for age and sex), who adhered to their diet for at least 1 year. Results Both δ15N and δ13C were significantly lower in both the serum and 24 h urine of vegans compared to omnivores. δ15N either in serum or urine had 100% specificity and sensitivity to discriminate between vegans and omnivores. Specificity of δ13C was also > 90%, while sensitivity was 93% in serum and 77% in urine. Conclusion δ15N both in serum and urine was able to accurately identify vegans and thus appears to be a promising marker for dietary habits.

• Suarez, Carolina; Sedlacek, Christopher J.; Gustavsson, David J. I.; Eiler, Alexander; Modin, Oskar & Hermansson, Malte [Show all 7 contributors for this article] (2022). Disturbance-based management of ecosystem services and disservices in partial nitritation-anammox biofilms. npj Biofilms and Microbiomes. 8(1). doi: 10.1038/s41522-022-00308-w. Full text in Research Archive Show summary

  Abstract The resistance and resilience provided by functional redundancy, a common feature of microbial communities, is not always advantageous. An example is nitrite oxidation in partial nitritation-anammox (PNA) reactors designed for nitrogen removal in wastewater treatment, where suppression of nitrite oxidizers like Nitrospira is sought. In these ecosystems, biofilms provide microhabitats with oxygen gradients, allowing the coexistence of aerobic and anaerobic bacteria. We designed a disturbance experiment where PNA biofilms, treating water from a high-rate activated sludge process, were constantly or intermittently exposed to anaerobic sidestream wastewater, which has been proposed to inhibit nitrite oxidizers. With increasing sidestream exposure we observed decreased abundance, alpha-diversity, functional versatility, and hence functional redundancy, among Nitrospira in the PNA biofilms, while the opposite patterns were observed for anammox bacteria within Brocadia . At the same time, species turnover was observed for aerobic ammonia-oxidizing Nitrosomonas populations. The different exposure regimens were associated with metagenomic assembled genomes of Nitrosomonas , Nitrospira , and Brocadia , encoding genes related to N-cycling, substrate usage, and osmotic stress response, possibly explaining the three different patterns by niche differentiation. These findings imply that disturbances can be used to manage the functional redundancy of biofilm microbiomes in a desirable direction, which should be considered when designing operational strategies for wastewater treatment.

• Durant, Joël; Ono, Kotaro & Langangen, Øystein Ole Gahr (2022). Empirical evidence of nonlinearity in bottom up effect in a marine predator-prey system. Biology Letters. ISSN 1744-9561. 18(11). doi: 10.1098/rsbl.2022.0309. Full text in Research Archive Show summary

  Strength of species interaction may have profound effects on population dynamics. Empirical estimates of interaction strength is often based on the assumption that the interaction strengths are constant. Barents Sea cod and capelin are two fish populations for which such interaction has been acknowledged and used, under the assumption of constant interaction strength, when studying their population dynamics. However, species interaction can often be non-linear in marine ecosystems and might profoundly change our understanding of food chains. Analysing 37 years long survey time series in the Arcto-Boreal Barents Sea with a state-space modelling framework, we demonstrate that the effect of capelin on cod is not linear but shifts depending on capelin abundance: while capelin is beneficial for cod population at high abundance, below the threshold, it becomes less important for cod. Our analysis therefore shows the importance of investigating non-linearity in species interaction and may contribute to an improved understanding on species assemblages.

• Osman, Omneya Ahmed; Andersson, Johan; Sanchez, Pedro Maria Martin & Eiler, Alexander (2022). National eDNA-based monitoring of Batrachochytrium dendrobatidis and amphibian species in Norway. Metabarcoding and Metagenomics. 6, p. 305–317. doi: 10.3897/mbmg.6.85199. Full text in Research Archive Show summary

  Freshwaters represent the most threatened environments with regard to biodiversity loss and, therefore, there is a need for national monitoring programs to effectively document species distribution and evaluate potential risks for vulnerable species. The monitoring of species for effective management practices is, however, challenged by insufficient data acquisition when using traditional methods. Here we present the application of environmental DNA (eDNA) metabarcoding of amphibians in combination with quantitative PCR (qPCR) assays for an invasive pathogenic chytrid species ( Batrachochytrium dendrobatidis - Bd ), a potential threat to endemic and endangered amphibian species. Statistical comparison of amphibian species detection using either traditional or eDNA-based approaches showed weak correspondence. By tracking the distribution of Bd over three years, we concluded that the risk for amphibian extinction is low since Bd was only detected at five sites where multiple amphibians were present over the sampled years. Our results show that eDNA-based detection can be used for simultaneous monitoring of amphibian diversity and the presence of amphibian pathogens at the national level in order to assess potential species extinction risks and establish effective management practices. As such our study represents suggestions for a national monitoring program based on eDNA.

• Oczkowski, Michał; Wilczak, Jacek; Dziendzikowska, Katarzyna; Øvrevik, Johan; Myhre, Oddvar & Lankoff, Anna [Show all 8 contributors for this article] (2022). Dietary Intervention with Blackcurrant Pomace Protects Rats from Testicular Oxidative Stress Induced by Exposition to Biodiesel Exhaust. Antioxidants. 11(8). doi: 10.3390/antiox11081562. Full text in Research Archive Show summary

  The exposure to diesel exhaust emissions (DEE) contributes to negative health outcomes and premature mortality. At the same time, the health effects of the exposure to biodiesel exhaust emission are still in scientific debate. The aim of presented study was to investigate in an animal study the effects of exposure to DEE from two types of biodiesel fuels, 1st generation B7 biodiesel containing 7% of fatty acid methyl esters (FAME) or 2nd generation biodiesel (SHB20) containing 7% of FAME and 13% of hydrotreated vegetable oil (HVO), on the oxidative stress in testes and possible protective effects of dietary intervention with blackcurrant pomace (BC). Adult Fisher344/DuCrl rats were exposed by inhalation (6 h/day, 5 days/week for 4 weeks) to 2% of DEE from B7 or SHB20 fuel mixed with air. The animals from B7 (n = 14) and SHB20 (n = 14) groups subjected to filtered by a diesel particulate filter (DPF) or unfiltered DEE were maintained on standard feed. The rats from B7+BC (n = 12) or SHB20+BC (n = 12), exposed to DEE in the same way, were fed with feed supplemented containing 2% (m/m) of BC. The exposure to exhaust emissions from 1st and 2nd generation biodiesel resulted in induction of oxidative stress in the testes. Higher concentration of the oxidative stress markers thiobarbituric acid-reactive substances (TBARS), lipid hydroperoxides (LOOHs), 25-dihydroxycholesterols (25(OH)2Ch), and 7-ketocholesterol (7-KCh) level), as well as decreased level of antioxidant defense systems such as reduced glutathione (GSH), GSH/GSSG ratio, and increased level of oxidized glutathione (GSSG)) were found. Dietary intervention reduced the concentration of TBARS, 7-KCh, LOOHs, and the GSSG level, and elevated the GSH level in testes. In conclusion, DEE-induced oxidative stress in the testes was related to the biodiesel feedstock and the application of DPF. The SHB20 DEE without DPF technology exerted the most pronounced toxic effects. Dietary intervention with BC in rats exposed to DEE reduced oxidative stress in testes and improved antioxidative defense parameters, however the redox balance in the testes was not completely restored.

• Skuland, Tonje Schwach; Grytting, Vegard Sæter; Låg, Marit; Jørgensen, Rikke Bramming; Snilsberg, Brynhild & Leseman, Daan L.A.C. [Show all 12 contributors for this article] (2022). Road tunnel-derived coarse, fine and ultrafine particulate matter: physical and chemical characterization and pro-inflammatory responses in human bronchial epithelial cells. Particle and Fibre Toxicology. 19(45). doi: 10.1186/s12989-022-00488-5. Full text in Research Archive Show summary

  Background Traffic particulate matter (PM) comprises a mixture of particles from fuel combustion and wear of road pavement, tires and brakes. In countries with low winter temperatures the relative contribution of mineral-rich PM from road abrasion may be especially high due to use of studded tires during winter season. The aim of the present study was to sample and characterize size-fractioned PM from two road tunnels paved with different stone materials in the asphalt, and to compare the pro-inflammatory potential of these fractions in human bronchial epithelial cells (HBEC3-KT) in relation to physicochemical characteristics. Methods The road tunnel PM was collected with a vacuum pump and a high-volume cascade impactor sampler. PM was sampled during winter, both during humid and dry road surface conditions, and before and after cleaning the tunnels. Samples were analysed for hydrodynamic size distribution, content of elemental carbon (EC), organic carbon (OC) and endotoxin, and the capacity for acellular generation of reactive oxygen species. Cytotoxicity and pro-inflammatory responses were assessed in HBEC3-KT cells after exposure to coarse (2.5–10 μm), fine (0.18–2.5 μm) and ultrafine PM (≤ 0.18 μm), as well as particles from the respective stone materials used in the pavement. Results The pro-inflammatory potency of the PM samples varied between road tunnels and size fractions, but showed more marked responses than for the stone materials used in asphalt of the respective tunnels. In particular, fine samples showed significant increases as low as 25 µg/mL (2.6 µg/cm2) and were more potent than coarse samples, while ultrafine samples showed more variable responses between tunnels, sampling conditions and endpoints. The most marked responses were observed for fine PM sampled during humid road surface conditions. Linear correlation analysis showed that particle-induced cytokine responses were correlated to OC levels, while no correlations were observed for other PM characteristics. Conclusions The pro-inflammatory potential of fine road tunnel PM sampled during winter season was high compared to coarse PM. The differences between the PM-induced cytokine responses were not related to stone materials in the asphalt. However, the ratio of OC to total PM mass was associated with the pro-inflammatory potential.

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• Stensrud, Eivind; Hyvärinen, Olli Petteri; Rostum, Tarjei; Angell, Thorvald; Knutsen, Halvor & Lundström, Karl [Show all 8 contributors for this article] (2026). PREDATORS AS SENTINELS: UNRAVELING TROPHIC SHIFTS IN A DARKENING FJORD USING dDNA AND STABLE ISOTOPES OVER THE LAST 20 YEARS. Full text in Research Archive Show summary

  The Greater Oslofjord, like many other coastal systems, is undergoing rapid ecological shifts driven by climate change, coastal freshening and darkening. To understand how these bottom-up stressors restructure food webs, we utilized a multi-trophic approach analyzing three sympatric predators (approx. 500 individuals): Harbour seals (Phoca vitulina), Great Cormorants (Phalacrocorax carbo), and Atlantic Cod (Gadus morhua). We combined dietary DNA (dDNA) metabarcoding with stable isotope analysis (δ13C, δ15N) to trace temporal and spatial dietary changes over 20 years. Traditional morphological methods often fail to capture soft-bodied prey and secondary consumption; thus, we used dDNA combined with novel reference databases to maximize taxonomic resolution. Our dDNA results revealed high-resolution predation data, including the detection of secondary consumption (zoo- and phytoplankton) alongside primary prey, effectively mapping the food web from top predators down to primary producers. Isotope data complemented this by delineating trophic niche widths and source of primary production (land vs. sea). We observed distinct dietary variations linking predator foraging behavior to environmental gradients. This included observable changes over the last 20 years, such as an increase in invasive species in their diet and a shift in zoo- and phytoplankton composition. These findings demonstrate that combining molecular and isotopic analysis of top predators provides a powerful tool for monitoring the cascading effects of anthropogenic changes on marine food webs.

• Carlsen, Eira Catharine Lødrup; Pismeniuk, Anfisa; Wei, Jing; Ippach, Mats Rouven; Dörsch, Peter & Westermann, Sebastian [Show all 9 contributors for this article] (2026). FROM PEAT TO PONDS: LANDSCAPE HETEROGENEITY DRIVES METABOLIC NETWORKS AND GREENHOUSE GAS RELEASE FROM THAWING PERMAFROST. Full text in Research Archive Show summary

  As permafrost landscapes degrade, they transform into a hydrological mosaic of dry palsas, collapsing thermokarst slumps, and water-saturated ponds. This physical reorganization creates steep gradients in redox potential and organic matter quality, fundamentally altering the thermodynamic constraints on microbial metabolism. We investigated greenhouse gas (CO2, CH4, N2O) production potentials across several permafrost thaw gradients in sub-Arctic peatlands of Northern Norway, linking landscape-scale changes to genome-resolved metabolic networks. By integrating high-resolution metagenomics with organic matter and greenhouse gas production characterization, we found that thaw features act as distinct thermodynamic bioreactors. In water-saturated, anoxic peat layers, oxygen limitation selects for "slow" metabolic guilds specialized in fermentation and methanogenesis while other oxygenated features are constrained by the quality of organic matter—specifically the accumulation of polyphenols and aromatic compounds acts as a metabolic "latch". We show that the shift from oxic to anoxic conditions triggers a non-linear restructuring of the microbial network, where less efficient central metabolism drives high N2O and CH4 yields but suppressed CO2 production. These findings demonstrate that predicting the permafrost-carbon feedback requires mapping the "metabolic landscape"—where organic matter quality and redox thresholds ultimately tune the greenhouse gas release from thawing landscapes to the atmosphere.

• Riis-Pedersen, Christine; Carlsen, Eira Catharine Lødrup; Lejzerowicz, Franck Laurent Patrick; Hessen, Dag Olav & Eiler, Alexander (2026). HOW OPTICS AND THERMODYNAMICS SHAPE METHANE EMISSIONS FROM LAKES. Full text in Research Archive Show summary

  The interactions of light regime and physical stratification can be argued to dictate greenhouse gas flux through determining the thermodynamics in lake systems. Using geochemical profiling and metagenomics, we reconstructed metabolic networks in a wide range of lakes including ferruginous (iron-rich) and euxinic (sulfide-rich) systems. We observed significant methane accumulation in the anoxic monimolimnion—up to 420 µM in ferruginous lakes—yet surface levels remained low, indicating a highly efficient biofilter at the chemoclines. We identified a tight thermodynamic coupling between phototrophs and methanotrophs driven by oxidant regeneration. In ferruginous lakes, anoxygenic phototrophs likely use reduced iron (Fe2+) as an electron donor. This process regenerates oxidized iron (Fe3+), while in euxinic light energy is utilized to recycle essential electron acceptors such as SO42- (e.g., Chlorobium), required for anaerobic methane oxidation. Oxygenic phototrophs (e.g., Cyanobium) detected at and above the chemocline likely provide oxygen. This supply sustains aerobic methanotrophs like Crenothrix and Methylobacter even in suboxic waters. Hence methanotrophic capacity is ultimately constrained by optical properties selecting for low-intensity light anoxygenic or high-intensity oxygenic phototrophs. Consequently, levels of chromophoric dissolved organic matter determine methane oxidation rates. We conclude that chemoclines function as dynamic, light-powered engines for methane removal, sensitive to brownification and climate-induced shifts in stratification.

• Heuschele, Jan David (2026). Combining citizen science with assisted image classification to determine taxa composition in Norwegian seaweeds. Full text in Research Archive
• Heuschele, Jan David & Johannessen, Ida (2026). Forskning på livet i havet - webinar 3. Full text in Research Archive
• Johannessen, Ida & Heuschele, Jan David (2026). Folkeforskning - Forskning på livet i havet. Full text in Research Archive
• Garvang, Even Sletteng; Skogvoll, Vidar & Andersen, Gard Lilledal (2026). Under Kappa #86 - The Thing vs. Mystique, med Gard Lilledal Andersen - Steinhard hud og skuespill. doi: https:/www.underkappa.no/2188463/episodes/19742123-86-the-thing-vs-mystique-med-gard-lilledal-andersen-steinhard-hud-og-skuespill. Full text in Research Archive
• Heuschele, Jan David & Garvang, Even Sletteng (2026). Hopp Hopp Hoppekreps - A Norwegian children's song about copepods. doi: 10.5281/ZENODO.22082053. Full text in Research Archive Show summary

  "Hopp hopp hoppekreps" is a children’s song about copepods. It aims to bring awareness to one of the most important animal groups in aquatic environments - copepods. The accompanying leaflet has two pages, one that takes the role of a children’s book and one showing the complete song text. In the children’s book, we take some of the verses and illustrate the biological context. The 2 pages are meant to be printed double-sided on sheet of A4 paper, then folded three times, and after a small cut on the indicated line, one can fold it into a mini booklet (or “zine"). The booklet is meant for distribution on science fairs or to be printed out at home as a small children's book.

• Sundfjord, Arild; Hallanger, Ingeborg G.; Halterskjær, Hans Erik; Christensen, Jacob Max; Czyz, Ceslav & Dinh, van Khuong [Show all 19 contributors for this article] (2026). Arctic Ocean 2025 A-TWAIN + HiAOOS cruise report: 22 October - 10 November 2025 (cruise ID:2025712). Full text in Research Archive Show summary

  Cruise report from the Norwegian Polar Institute's Arctic Ocean cruise 2025. The report details work done and data/samples collected, plus recovery and deployment of deep ocean instrument moorings. All data collected by the Norwegian Polar Institute and all bottle sample data from UiT - The Arctic University of Tromsø during the cruise are made available through the Norwegian Polar Data Centre at DOI https://doi.org/10.21334/npolar.2025.1c59d3fb.

• Folkehelseinstituttet; Berstad, Paula Marianna; Helleve, Arnfinn; Indseth, Thor; Kløvstad, Hilde & Knudsen, Ann Kristin Skrindo [Show all 8 contributors for this article] (2026). Temautgave av Folkehelserapporten: De viktigste folkehelseutfordringene. Full text in Research Archive Show summary

  I denne rapporten gir FHI en oversikt over helsetilstanden i Norge, og faktorer som påvirker den. Vi går gjennom både overordnede samfunnsforhold, store folkehelseutfordringer, og helsetrusler. Noen særlig viktige samfunnsforhold som har stor påvirkning på folkehelsen i dag og framover, er at vi har en aldrende befolkning, som setter press på helsetjenestene og samfunnets bærekraft både ved at antallet eldre øker, og at andelen øker opp mot den arbeidsføre befolkningen. Sosial ulikhet i helse er fortsatt en folkehelseutfordring og blir ytterligere komplisert av innvandring. Svekket internasjonalt samarbeid om beredskap, en urolig geopolitisk situasjon, digitalisering av samfunnet og endrede holdninger til kunnskap påvirker folkehelsearbeidet i Norge. Folkehelsen og livskvaliteten i Norge er god. Vi lever lenge og andelen friske leveår har økt. Lengre levetid bidrar imidlertid til at år levd med helsetap også øker. Ikke-smittsomme sykdommer er hovedårsaken til sykdomsbyrden i Norge. Vi trekker i denne rapporten særlig fram to utfordringer: Psykiske lidelser blant barn og unge har økt, særlig etter 2010, og fortsetter å øke. Dette påvirker livskvalitet gjennom hele livsløpet, og samfunnsdeltakelse i utdanning og arbeidsliv. Sosiale ulikheter forsterker disse effektene. Tidlig forebygging av psykiske lidelser hos unge kan gi store gevinster for samfunnsdeltakelse og folkehelse. En annen utfordring er sykdom i en aldrende befolkning. En stadig høyere andel lever mange år med sykdom, og oftere med flere sykdommer, hvor hjerte- og karsykdommer, kreft og demens utgjør en vesentlig del. Flere av sykdommene innenfor disse hovedgruppene er i stor grad forebyggbare. Framskrivninger av norske helseutgifter viser at demens, hjerneslag og diabetes vil være de viktigste kostnadsdriverne fram mot 2050. Helsetrusler omfatter både akutte hendelser og langsiktige utviklingstrekk som kan påvirke folkehelsen. De viktigste truslene fremover er komplekse og henger sammen med globale endringer. Pandemier og smittsomme sykdommer vil fortsatt kunne være store utfordringer, forsterket av blant annet global mobilitet, urbanisering og svekket internasjonalt samarbeid. Antimikrobiell resistens (AMR) er en langsomt voksende trussel som kan gjøre behandling av infeksjoner vanskelig og true moderne medisinsk praksis. Forhold som svekker vaksinasjonsdekning kan bidra til økt risiko for utbrudd av alvorlige smittsomme sykdommer, flere sykehusinnleggelser, høyere dødelighet og økt antibiotikabruk. Ellers trekker vi også fram sårbarhet knyttet til drikkevann, faren for kjemikaliehendelser og syntetisk biologi som trusler som krever god beredskapsevne. Klimaendringer er vurdert som en forsterker av andre trusler. Det ligger store muligheter i å forebygge uhelse. Forebygging er den mest kostnadseffektive strategien for å redusere sykdomsbyrden. Det er behov for å styrke kunnskapen om effektive folkehelsetiltak og forebyggende tiltak i helsetjenestene. For en stor del av sykdomsbyrden er de underliggende risikofaktorene ikke kjent eller forstått, og her ligger det potensial for å forebygge sykdom gjennom å skaffe kunnskap om risiko- og årsaksfaktorer. God overvåking og beredskap, internasjonalt og tverrsektorielt samarbeid og forebyggende tiltak er avgjørende for å holde forekomsten av smittsomme sykdommer lav og redusere konsekvensene av helsetrusler. Fremtidens folkehelsearbeid må styrke den tverrsektorielle tilnærmingen og se på etablerte utfordringer og akutte helsetrusler i sammenheng.

• Supraha, Luka; Heuschele, Jan David & Leu, Eva (2026). From Ice to Open Water: Response of Arctic Mircoalgae to Changing Environmental Drivers. Full text in Research Archive
• Heuschele, Jan David & Johannessen, Ida (2026). Forskning på livet i havet - Webinar 2. Full text in Research Archive
• Riis-Pedersen, Christine; Carlsen, Eira Catharine Lødrup; Hessen, Dag Olav; Lejzerowicz, Franck Laurent Patrick; Andersen, Tom & Dörsch, Peter [Show all 8 contributors for this article] (2025). Microbial drivers of methane cycling in meromictic as compared to holomictic lakes. Full text in Research Archive
• Carlsen, Eira Catharine Lødrup; Wei, Jing; Lejzerowicz, Franck Laurent Patrick; Ippach, Mats Rouven; Pismeniuk, Anfisa & Kjær, Sigrid Trier [Show all 10 contributors for this article] (2025). Greenhouse gas production kinetics and metabolic traits in thawing permafrost peat. Full text in Research Archive Show summary

  While numerous drivers of greenhouse gas emission (GGE) have been suggested to drive variabilities across thawing landscapes, experimental validations are still widely lacking . Here, I will present results from several experimental studies capturing drivers of GGE across thawing permafrost landscapes like redox, organic matter and microbial source community. Our findings reveal clear responses of the greenhouse gases to redox conditions across the landscape. CO2 production showed a drastic decline when O2 dropped below 100 μM; specifically, under anoxic conditions, CO2 yield and maximum net production rates decreased by around 90 % compared to oxic conditions. CH4 levels remained consistent across O2 gradients, until at least 6 months upon thawing. Functional groups like N2O reducers, fermenters, denitrifiers, and sulfur reducers increased under anoxic conditions, and the reduced CO2 production rates and yields under anoxic conditions were reflected by genomic changes towards reduced central metabolic efficiency. Our data thus points towards critical GGE thresholds under suboxic conditions across thawing landscapes. Moreoever, gas dynamics seem to be primarily influenced by permafrost conditions rather than source community colonization. Our experiments provide increased knowledge on the variable GGE across thawing permaforst landscapes influenced by variable redox conditions and permafrost´s organic matter legacy.

• Edvardsen, Bente (2025). Marine microalgae and other microbes. Full text in Research Archive
• Nyeggen, Margot Ulfsdatter; Christiansen, Svenja; Garvang, Even Sletteng; Andersen, Tom; Heuschele, Jan David & Titelman, Josefin (2025). Zooplankton community dynamics in Oslofjorden. Full text in Research Archive
• Garvang, Even Sletteng; Heuschele, Jan David; Konestabo, Heidi Sjursen; Andersen, Tom; Riemann, Lasse & Titelman, Josefin (2025). Replication Data for: Parasite infection shapes the pathobiome and behavior of marine zooplankton. doi: https:/scholar.google.com/citations?view_op=view_citation&hl=sv&user=ycTVkNkAAAAJ&sortby=pubdate&citation_for_view=ycTVkNkAAAAJ%3A3s1wT3WcHBgC. Full text in Research Archive Show summary

  We collected Calanus helgolandicus from the Oslofjord, both healthy individuals and infected with a conspicuous" yellow-hyphal" parasite that changes the host behavior. We incubated them for 7 days and measured behavior and survival. At the start and end of the incubation we sampled animals for 16S rRNA microbial community analysis. Infected Calanus had higher mortality, more risky behavior and altered microbiomes compared to the uninfected.

• Titelman, Josefin (2025). Parasite disease in copepods. Full text in Research Archive
• Heuschele, Jan David & Johannessen, Ida (2025). Forskning på livet i havet - webinar 1. Full text in Research Archive
• Heuschele, Jan David; Markova, Yana; Striebel, Maren; Andersen, Tom & Titelman, Josefin (2025). Uferflucht - Shore avoidance and other zooplankton dynamics in a coastal ecosystem. Full text in Research Archive
• Giebichenstein, Julia; Warner, Nicholas Alexander; Harju, Mikael; Routti, Heli Anna Irmeli; Varpe, Øystein & Gabrielsen, Geir W. [Show all 7 contributors for this article] (2025). SHORT- AND MEDIUM-CHAIN CHLORINATED PARAFFINS IN AN ARCTIC MARINE FOOD CHAIN. Full text in Research Archive
• Giebichenstein, Julia; Dupont, Nicolas; Harju, Mikael; Varpe, Øystein; Gabrielsen, Geir W. & Andersen, Tom [Show all 7 contributors for this article] (2025). Seasonal Insights into Pollutant Accumulation and Biomagnification in an Arctic Marine Food Web. Full text in Research Archive
• Edvardsen, Bente; Fon, Mathias & Eikrem, Wenche (2025). Biology, toxicity and ecology of Chrysochromulina leadbeateri. Full text in Research Archive
• Vindenes, Yngvild (2025). Ageing, fitness, and ectotherm responses to climate warming: Do increased rates of ageing reduce population viability in a warmer world? Full text in Research Archive
• Skogvoll, Vidar; Garvang, Even Sletteng; Wahl, Andreas Solberg; Dahlen, Pia Ve; Andersen, Gard Lilledal & Røyne, Anja (2025). Under Kappa #55 - Fantastiske 4: Mysteriet i Oslo. doi: https:/www.youtube.com/watch?app=desktop&v=phUVkoJXPJM. Full text in Research Archive
• Heuschele, Jan David (2025). Uferflucht in a dynamic coastal habitat, or from POICE to MACROCOP. Full text in Research Archive
• Assmy, Philipp Kurt Wolf; Bailey, Allison Michelle; Daase, Malin; Edvardsen, Bente; Eikrem, Wenche & Hopp, Clara J.M. [Show all 16 contributors for this article] (2025). Extensive summer blooms in fjords of West Spitsbergen triggered by run-off from land. Full text in Research Archive Show summary

  Primary production in Svalbard fjords is highly seasonal with the largest fraction of annual primary production traditionally associated with the phytoplankton spring bloom, usually peaking in May. The spring bloom is terminated when winter accumulated nutrients in surface waters are exhausted and typically followed by a post-bloom period characterized by low phytoplankton biomass. Here we report on extensive phytoplankton blooms in fjords of West Spitsbergen during late-June 2024 occurring four weeks after the peak of the spring bloom and coinciding with the snow freshet period. We focus on bloom development in Kongsfjorden and explore the environmental drivers that triggered this bloom. The bloom developed in the upper 5 – 15 m of the water column with exceptionally high chlorophyll-a concentrations of up to 25 µg L-1. Its species composition was distinctly different from the spring bloom, dominated by diatoms, and almost exclusively dominated by a pelagophyte species new to science. Surface currents, nutrient and chlorophyll-a profiles and satellite images indicate that the bloom developed inside the fjord and was subsequently advected onto the adjacent shelf. Since post-spring bloom nitrate concentrations in fjord surface waters were completely exhausted in the upper 25 m, we hypothesize that this bloom was triggered by land-derived nutrients associated with meltwater run-off, highlighting terrestrial drivers of marine primary production in fjord ecosystems. Such extensive blooms during early summer are unusual and could possibly be associated with the record melt on Svalbard in summer 2024.

• Solhaug, Anita; Fon, Mathias; Wang, Xinhui; Chen, An; Ghesquiere, Rosalie & Andersen, Aaron John Christian [Show all 15 contributors for this article] (2025). The cytotoxicity of the haptophyte Chrysochromulina leadbeateri towards gill cell lines. Full text in Research Archive
• Larsen, Thomas Ostenfeldi; Wang, Xinhui; Samdal, Ingunn Anita; Andersen, Aaron John Christian; Solhaug, Anita & Garrido, Bruno [Show all 12 contributors for this article] (2025). Structure elucidation of Leadbeaterin-1: The main fishkilling toxin from Chrysochromulina leadbeateri blooms in Northern Norwegian fjords. Full text in Research Archive
• Miles, Christopher Owen; Løvberg, Kjersti Eriksen; Rasmussen, Tone; Michelsen, Helena Kling; Rangel-Huerta, Oscar Daniel & Larsen, Thomas O. [Show all 11 contributors for this article] (2025). Sterolysin diversity during fish-killing Chrysochromulina leadbeateri blooms in northern Norway. Full text in Research Archive Show summary

  A major bloom of the haptophyte C. leadbeateri in 2019 killed 7.5 million farmed salmon, corresponding to a direct economic loss of €85 million, and indirect losses of €210–250 million. Very recently, we reported the isolation and structure elucidation by LC-HRMS/MS and NMR spectroscopy of a new fish-killing toxin, named leadbeaterin-1, in the ToxANoWa project.1,2 The presence of 5 other putative leadbeaterins was also revealed by LC–HRMS analyses of algal cultures.1 In May–June 2025, another C. leadbeateri bloom occurred in the same region, resulting in the deaths of ca. 2 million farmed salmon. LC–HRMS/MS analyses of extracts from passive samplers (SPATT disks) and SPE of water from stored and fresh samples from the two blooms, and samples from cultures (including a culture from 1991), were performed, including targeted metabolomics approaches. These revealed a rich array of related compounds, including putative precursors, metabolites, and degradation products. Here we report an update on findings from these studies and tentative structures for some of the major analogues. The implications of this sterolysin diversity for potential monitoring and early-warning strategies will also be discussed. References: 1. Wang X, Fon M, Andersen AJC, Solhaug A, Ingebrigtsen RA, Samdal IA, et al. Insights into the nature of ichthyotoxins from the Chrysochromulina leadbeateri blooms in northern Norwegian fjords. Harmful Algae. 2024;137:102681. 2. Wang X, Solhaug A, Mudge EM, Garrido BC, Fon M, Andersen AJC, et al. Structure elucidation of leadbeaterin-1: the main fish-killing toxin from Chrysochromulina leadbeateri blooms in northern Norwegian fjords. J. Agric. Food Chem. (manuscript in preparation).

• Samdal, Ingunn Anita; Miles, Christopher Owen; Solhaug, Anita; Edvardsen, Bente; Larsen, Thomas Ostenfeld & Michelsen, Helena Kling [Show all 7 contributors for this article] (2025). Chrysochromulina leadbeateri & toksinet – i prosjektet ToxANoWa. Full text in Research Archive
• su, Audrey; Jourdain, Eve Marie; Andvik, Clare Margaret; Rikardsen, Audun H.; Søderstrøm, Sofie & Blévin, Pierre [Show all 7 contributors for this article] (2025). Den forgiftede hvalen Elida. [Internet]. web, social media. doi: https:/akvaplan.no/no/video/2025-09-29/den-forgiftede-hvalen-elida-121104. Full text in Research Archive
• Garvang, Even Sletteng (2025). Det gule mysteriet - og andre parasitter i hoppekreps. doi: https:/www.youtube.com/watch?v=2LSG9akmNbY. Full text in Research Archive Show summary

  Hoppekreps dominerer i verdens største økosystem: de frie vannmassene i havet. De er verdensmestere i å ikke bli spist i et miljø der alle vil spise dem, og har utviklet seg for å finne både mat og en partner i et hav der det er tonnevis av vann mellom dem og målene deres. Men det lurer andre farer enn predatorer i planktonet, og kanskje er hoppekrepsen offer for sin egen suksess?

• Garvang, Even Sletteng; Heuschele, Jan David; Konestabo, Heidi Sjursen; Andersen, Tom; Riemann, Lasse & Titelman, Josefin (2025). Parasite infection shapes the pathobiome and behavior of copepods. Full text in Research Archive
• Mahlangu, Sibusiso; Ewers, Isabelle; Carvalho, Cintia Oliveira; Schrøder-Nielsen, Audun; Dunthorn, Micah & Karlsen, Hans Erik [Show all 12 contributors for this article] (2025). Investigating the dynamics of the aquatic community in Oslofjord through time series analysis of eDNA. BioRxiv. ISSN 0362-4331. doi: 10.1101/2025.02.05.636659. Full text in Research Archive
• Heuschele, Jan David (2025). Plankton i Oslofjorden. Full text in Research Archive
• Vogt, Rolf David; Kaste, Øyvind; Thrane, Jan-Erik; Balkoni, Areti; Clayer, Francois & Wit, Heleen de [Show all 7 contributors for this article] (2025). Distinguishing the Effects of Climate Change and Acid Rain Recovery on Water Chemistry Trends: A Challenging Task? doi: 10.3897/aca.8.e155377. Full text in Research Archive Show summary

  This study examines whether trends in climate variables—precipitation, runoff, temperature, and actual evapotranspiration (AET)—can help explain changes in water chemistry in 78 Norwegian lakes from 1990 to 2020. AET has increased significantly in nearly all catchments, though substantial discrepancies exist between modeled and calculated values. Temperature has risen at 79% of monitoring stations, whereas precipitation and runoff exhibit significant trends in only 15% and 19% of lakes, respectively. These patterns are reflected in the limited explanatory power of climate variables for water chemistry changes. Spatial and temporal correlations between climate trends and acid rain recovery further complicate distinguishing their individual effects in simple correlation analyses. Overall, climate variables show weak explanatory power for water chemistry trends. However, multivariate redundancy analysis (RDA) provides a non-significant indication that increases in precipitation and runoff may counteract the effects of rising temperatures on water chemistry.

• Andvik, Clare Margaret; Jourdain, Eve Marie; Borgen, Anders; Lyche, Jan Ludvig; Karoliussen, Richard & Haug, Tore [Show all 7 contributors for this article] (2025). Intercorrelations of short-, medium- and long-chain chlorinated paraffins, dechloranes and legacy POPs in 10 species of marine mammals from Norway, in light of dietary niche. Full text in Research Archive
• Heuschele, Jan David (2025). Introduction to the MACROCOP project - The hidden role of copepods in coastal macroalgae for marine ecosystem functioning. Full text in Research Archive
• Wang, Xinhui; Solhaug, Anita; Mudge, Elizabeth M.; Garrido, Bruno C.; Fon, Mathias & Andersen, Aaron [Show all 14 contributors for this article] (2025). Leadbeaterins, novel ichthyotoxic sterolysins from the haptophyte Chrysochromulina leadbeateri, responsible for massive fish kills in Norway. Full text in Research Archive
• Dinh, van Khuong & Vu, Thi Thuy Minh (2025). Species-specific seasonal variations in thermal performance curves shape the direct and transgenerational vulnerability to marine heatwaves. Journal of Animal Ecology. ISSN 0021-8790. doi: 10.1111/1365-2656.70016. Full text in Research Archive
• Vogt, Rolf David; Kaste, Øyvind; Thrane, Jan-Erik; Balkoni, Areti; Clayer, François & Wit, Heleen de [Show all 7 contributors for this article] (2025). Is it possible to easily distinguish the effects of climate change and the decline in acid rain on trends in water chemistry? Full text in Research Archive
• Heuschele, Jan David; Nyeggen, Margot Ulfsdatter & Titelman, Josefin (2024). Ecotaxa ID 15537, Continuous Particle Imaging and Classification System (CPICS) images. doi: https:/ecotaxa.obs-vlfr.fr/prj/15537. Full text in Research Archive
• Dinh, van Khuong; Lutier, Mathieu; Albini, Dania; Dijkstra, Jildou; Thomsen, Nele & Albertsen, Milla Mona Sophie [Show all 11 contributors for this article] (2024). Life and death of overwintering Arctic zooplankton under multiple stressors in the Anthropocene. Full text in Research Archive
• Nygård, Elise; Kline, Simon Hasselø; Valestrand, Louise & Edvardsen, Bente (2024). Exploration of community dynamics of protists during the autumn season through metabarcoding and intensive sampling. Full text in Research Archive Show summary

  Increasing anthropogenic stressors and climate change are contributing to shifts in phytoplankton communities, which has significant consequences for marine ecosystems and biogeochemical cycles. Temperate regions, like Southern Norway, have distinct spring and autumn phytoplankton blooms which often differ in species composition due to variations in temperature, salinity, and light conditions, as well as nutrient availability. However, the autumn bloom is less explored than the spring bloom. Traditionally, phytoplankton monitoring programs collect samples once a month in the production period, this frequency may miss important aspects of population dynamics and species composition, especially during periods with rapid environmental and biological changes. This master’s project aims to get a better understanding of the phytoplankton autumn bloom in the Oslofjord. We intend to see if there is a difference in the composition and timing of the autumn bloom between the inner and outer Oslofjord, and whether frequent sampling reveals more of the changes over time and locality than traditional monthly sampling. This will be done through water sampling twice a week for about a month (mid-September to mid-October) in 2023 and 2024 from two marine sampling stations. The community diversity and composition will be examined by high throughput Illumina sequencing (using the V4 region of the 18S rRNA gene). Environmental factors, such as chlorophyll-a concentrations, along with nutrient and cDOM will be measured. Preliminary results from 2023 indicate differences in chlorophyll-levels between the stations, as well as temporal differences. Additionally, there appears to be weekly fluctuations in chlorophyll levels even with frequent sampling.

• Garvang, Even Sletteng (2024). Zooplankton pandemics - Parasite outbreaks in copepod populations. Full text in Research Archive
• Jourdain, Eve Marie (2024). Alle henger med alle, men familie er viktigst for norske spekkhoggere. [Journal]. Forskning.no. Full text in Research Archive
• Kline, Simon Hasselø; Saubrekka, Karoline; Eikrem, Wenche; Valestrand, Louise; Egge, Elianne Dunthorn & Eiler, Alexander [Show all 8 contributors for this article] (2024). Seasonal dynamics of the protist community in the Oslofjord and Skagerrak in a changing ocean. Full text in Research Archive Show summary

  Protists and prokaryotes compose approximately 90% of the biomass in the oceans, and any changes within this microbial community are likely to have reverberating effects throughout the ecosystem. Due to climate coastal marine systems are experiencing increased freshwater discharge from land and a darkening of the water column along with changes in nutrient concentrations. The phenology is also changing and in the inner Oslofjord the spring blooms starts on average 2 weeks later that 15 years ago. The causes for this delay in unclear. In this study we examine the diversity and seasonal dynamics of the protist community by metabarcoding in the inner and outer Oslofjord, and possible changes during 14 years. Monthly plankton samples were collected at two localities and two depths during 2023 and similar samples were collected in 2009-2011, to be sequenced by current high throughput technology (Illumina). Various environmental parameters have been measured including CDOM (colored dissolved organic matter). We ask whether browning or other physico-chemical conditions can explain the delayed spring bloom and other observed changes in the protist community in the Oslofjord and Skagerrak.

• Myrann, Olav; Kline, Simon Hasselø; Andersen, Tom & Edvardsen, Bente (2024). The effects of light and salinity on growth of spring bloom diatoms in the Oslofjord. Full text in Research Archive Show summary

  Diatoms dominate during the spring bloom in the Oslofjord, with members of the genera Skeletonema, Thalassiosira and Chaetoceros being among the most abundant. During the last 15 years there has been a recorded reduction in Skeletonema abundance during the spring bloom in the Inner Oslofjord, that may explain an overall reduction of diatom abundance. In comparison the concentration of other diatoms such as Chaetoceros spp. has remained stable in the same period. The concentration of dinoflagellates has remained stable in contrast to the decrease of diatom concentration since 2006. The main aim of this master’s project is to obtain further knowledge on the abiotic factors affecting the important spring bloom diatom genera Skeletonema, Chaetoceros and Thalassiosira, and how environmental changes may affect their growth. To reach these aims, two different growth experiments using diatom cultures isolated from the spring bloom in the Oslofjord will be employed: 1) growing strains of Skeletonema and Chaetoceros separately under a combination of varying salinity and light intensity, and 2) conducting a common garden growth experiment with cultures of two additional diatom cultures Chaetoceros and Thalassiosira resulting in 4 species in total. The common garden growth experiment will test various conditions of salinity. The project will give insight into the dynamics of the spring blooming diatoms in the Oslo fjord and how they are affected by changes in salinity along with their interactions.

• Jemterud, Torkild; Bjorå, Charlotte Sletten; Sletsjøe, Arne Bernhard & Garvang, Even Sletteng (2024). Abels tårn. [Radio]. NRK P2. Full text in Research Archive
• Eliassen, Sigurd, skaar; Kline, Simon Hasselø; Andersen, Tom & Edvardsen, Bente (2024). Investigating the phytoplankton spring bloom dynamics n the Oslofjord by single species and common garden growth experiments. Full text in Research Archive Show summary

  During the last 15 years there has been a gradual decrease of diatom concentration during the spring bloom in the inner Oslofjord. A part of this decrease may be explained by decrease of the concentration of the genus Skeletonema, while other important diatom genera such as Chaetoceros and Thalassiosira have maintained a stable concentration since 2006. The reason for this is unclear. Possible causes for these changes include changes of the physical or chemical conditions. One potential driver of the observed changes can be coastal darkening due to climate change leading to shifting phytoplankton dynamics in the inner Oslofjord. An increase of light absorbing molecules of dissolved coloured organic matter (cDOM) transferred to the fjord from river input could reduce the growth of phytoplankton and potentially also shift the spring bloom to a later date. Under conditions with limited light, the phytoplankton taxa with the ability to grow at the lowest light intensity may be able to outcompete other competitors for the available light. The aim of this master’s project is to get a better understanding of the dynamics of important spring bloom diatoms in the Oslofjord and possible explanations to the observed changes. By single-species growth experiments I will determine the compensation light intensity of strains of two diatom genera Chaetoceros and Thalassiosira grown at different salinities. In a common garden experiment strains of the two diatom genera will be grown together with a strain of Skeletonema under different light conditions, to determine their competitive ability to limiting irradiance. This may contribute to a better understanding of the changes in the spring bloom dynamic observed in the Oslofjord since 2006.

• Garvang, Even Sletteng (2024). Zooplankton pandemics – Conditions for parasite outbreaks in copepod populations. Full text in Research Archive
• Wahl, Andreas; Lie-Jensen, Anette Christensen & Kline, Simon Hasselø (2024). Jøss?! #141 - Biespy, avskyelig snømann som bonde og fulle menns interesse for fastbundet dame (Podcast). Full text in Research Archive
• Edvardsen, Bente (2024). History of haptophyte and other ichthyotoxic algal blooms in Scandinavia. Full text in Research Archive
• Fon, Mathias (2024). Using the ASG-10 cell line to understand the toxicity of living Chrysochromulina leadbeateri. Full text in Research Archive
• Kaartvedt, Stein; Christiansen, Svenja & Titelman, Josefin (2024). Internal waves and fine-scale zooplankton sampling: Comment on Dewar-Fowler et al. (2023). Marine Ecology Progress Series. ISSN 0171-8630. 734, p. 173–175. doi: 10.3354/meps14577. Full text in Research Archive
• Skogvoll, Vidar; Garvang, Even Sletteng & Reinertsen, Marianne (2024). Under kappa - #21 - Wonder woman - Lassojuss, løgndetektorer og pistolreker med marianne reinsertsen. [Radio]. Podcast. Full text in Research Archive
• Albini, Dania; Lutier, Mathieu; Heimböck, Martin Paul; Heuschele, Jan David; Søreide, Janne & Jackson, Michelle C [Show all 7 contributors for this article] (2024). Temporal patterns in multiple stressors shape the vulnerability of overwintering Arctic zooplankton. Full text in Research Archive
• Andersen, Ida Yasin; Bendiksen, Kristian; Slangsvold, Einar Lie; Skogvoll, Vidar & Garvang, Even Sletteng (2024). Studio 2 - Påskeharen som superhelt. [Radio]. P2. Full text in Research Archive
• Skogvoll, Vidar; Garvang, Even Sletteng; Brugård, Anne & Ottem, John Christian (2024). Under Kappa - #29 - The Riddler - Gode nøtter, smarte dyr og spillteori med Anne Brugård og John Christian Ottem. [Radio]. Podcast. Full text in Research Archive
• Skogvoll, Vidar & Garvang, Even Sletteng (2024). Under Kappa - #28 - Professor X - Live! Mutantgener og fysikken bak hjernekontroll. Full text in Research Archive
• Skogvoll, Vidar; Garvang, Even Sletteng & Hval, Halvor Høen (2024). Under kappa - #25 - Green lantern - Batterier, farger, følelser og plancks konstant med halvor høen hval. [Radio]. Podcast. Full text in Research Archive
• Vogt, Rolf David; Garmo, Øyvind Aaberg; Austnes, Kari; Kaste, Øyvind; Haaland, Ståle Leif & Sample, James Edward [Show all 10 contributors for this article] (2024). Factors Governing Site and Charge Density of Dissolved Natural Organic Matter (DNOM). Full text in Research Archive
• Dinh, van Khuong (2024). Arctic multiple stressor research: life and death of the Arctic zooplankton in the Anthropocene. Full text in Research Archive
• Carvalho, Cintia Oliveira; Gromstad, William Esbjug; Dunthorn, Micah; Karlsen, Hans Erik; Schrøder-Nielsen, Audun & Ready, Jonathan Stuart [Show all 10 contributors for this article] (2024). Unveiling fish community dynamics in the Oslo fjord through eDNA metabarcoding. Full text in Research Archive
• Milne, Stephanie; Andvik, Clare Margaret; Jourdain, Eve Marie; Karoliussen, Richard; Vongraven, Dag & Øien, Nils Inge [Show all 8 contributors for this article] (2024). Temporal trends of dietary patterns and mercury in Norwegian killer whales from contrasting ecosystem states. Full text in Research Archive
• Lee, Kiah Jane Oland; Jourdain, Eve Marie; Remili, Anaïs; Andvik, Clare Margaret; Fagerlund, Carl Johan Ludwig & McKinney, Melissa [Show all 8 contributors for this article] (2024). Profiling the diet of Norwegian killer whales through quantitative fatty acid signature analysis (QFASA) and mercury accumulation. Full text in Research Archive
• Jemterud, Torkild; Skogvoll, Vidar & Garvang, Even Sletteng (2024). Abels tårn - Hva slags superkrefter har påskeharen? [Radio]. P2. Full text in Research Archive
• Kroglund, Ingvild Buran; Ciesielski, Tomasz Maciej; Østnes, Jan Eivind; Patten, Michael Allen; Borgå, Katrine & Jaspers, Veerle Leontina B (2024). Influence of different habitat characteristics on the concentration of elements in feathers and blood of a resident raptor species (tawny owls) in the Subarctic region. Full text in Research Archive
• Langangen, Øystein Ole Gahr; Olsen, Tora; Durant, Joël; Ottersen, Geir & Eriksen, Elena (2024). Poleward shift in spawning leads to smaller Atlantic cod offspring. Full text in Research Archive
• Langangen, Øystein Ole Gahr; Olsen, Tora; Durant, Joël; Ottersen, Geir & Eriksen, Elena (2024). Poleward shift in spawning leads to smaller Atlantic cod offspring. Full text in Research Archive
• Opdal, Anders Martin Frugård; Lindemann, Christian; Fiksen, Øyvind; Hessen, Dag Olav; Andersen, Tom & Aksnes, Dag Lorents (2024). Land use change and coastal water darkening drive synchronous dynamics in phytoplankton and fish phenology on centennial time scales. Full text in Research Archive
• Andvik, Clare Margaret; Jourdain, Eve Marie; Dulgheriu, Daniela; Lyche, Jan Ludvig; Karoliussen, Richard & Ruus, Anders [Show all 7 contributors for this article] (2024). Blubber Cortisol Levels in Norwegian Killer Whales: Accounting for Individual Variation is Vital in Assessing Stress Responses to Whale Watching. Full text in Research Archive
• Wang, Xinhui; Fon, Mathias; Andersen, Aaron John Christian; Solhaug, Anita; Ingebrigtsen, Richard Andre & Samdal, Ingunn Anita [Show all 10 contributors for this article] (2024). Ichthyotoxins from the Chrysochromulina leadbeateri blooms in Northern Norwegian fjords. Full text in Research Archive
• Abe, Keita; Diekert, Florian Klaus; Melsom, Arne & Langangen, Øystein Ole Gahr (2024). Author Correction: Do fishers follow fish displaced by climate warming? npj Ocean Sustainability. 3(1). doi: 10.1038/s44183-024-00066-6. Full text in Research Archive
• Edvardsen, Bente; Fon, Mathias; Wang, Xinhui; Larsen, Thomas Ostenfeldt & Solhaug, Anita (2024). Chrysochromulina leadbeateri causing massive fish mortalities in Northern Norway – its growth, toxicity and toxins. Full text in Research Archive
• Samdal, Ingunn Anita; Uhlig, Silvio; Solhaug, Anita; Fon, Mathias; Miles, Christopher Owen & Rangel-Huerta, Oscar Daniel [Show all 12 contributors for this article] (2024). Ny forståelse rundt hvorfor millioner av oppdrettslaks døde av algegift i 2019. Full text in Research Archive
• Ziegler, Amanda; Jørgensen, Lis Lindal; Bluhm, Bodil Annikki Ulla Barbro; Giebichenstein, Julia; Borgå, Katrine & Freitas, Thaise Ricardo de (2023). The effect of ice-free summer conditions on benthic food web structure in the Barents Sea. Full text in Research Archive Show summary

  Reduced Arctic sea-ice cover has been shown to alter phytoplankton community composition and reduce the magnitude of vertical flux, thereby reducing the strength of pelagic-benthic coupling. It is predicted that Arctic shelf ecosystems, like the Barents Sea, will transition into sub-polar-like ecosystems under future climatic conditions. However, few studies have provided a benthic perspective to the question of how ice-free conditions in the Arctic will affect food web structure. In this study, we aim to test whether ice-free summer conditions in the Barents Sea and adjacent Nansen Basin alter benthic food web structure and the strength of pelagic benthic coupling. To do so, we used bulk stable isotopes of carbon and nitrogen measured in food sources and benthic consumers, demersal fish, and zooplankton collected during summers with contrasting sea-ice conditions: August 2018 – low sea-ice extent and August 2019 – high sea-ice extent. We compared benthic food web structure across three oceanographically distinct regions from the sea-ice free central Barents Sea shelf and the seasonally ice-free northern Barents Sea shelf to the slope extending into the Nansen Basin. The results of this work will not only improve our understanding of the impact that Arctic sea-ice loss has on benthic communities but provide additional insight to the resiliency of Arctic benthic food webs.

• Jourdain, Eve Marie; Borgå, Katrine; Ruus, Anders & Andvik, Clare Margaret (2023). Spekkhoggerflokken trues av gammel gift. Forskerne følger dem tett. [Journal]. Titan.uio.no. Full text in Research Archive
• Dijkstra, Jildou; Schott, Schott; Thomsen, Nele; Lutier, Mathieu; Dinh, van Khuong & Reinardy, Helena Christine [Show all 7 contributors for this article] (2023). Influence of ocean warming and acidification on Arctic zooplankton during the polar night. Full text in Research Archive
• Edvardsen, Bente; Fon, Mathias; Reitzel, Helene; Šupraha, Luka; Andersen, Tom & Uhlig, Silvio (2023). Growth preferences of the haptophyte Chrysochromulina leadbeateri forming ichthyotoxic blooms in fjords in N Norway. Full text in Research Archive Show summary

  Microalgal flagellates of the genera Chrysochromulina and Prymnesium may form extensive blooms in marine and brackish waters causing fish kills. Chrysochromulina leadbeateri blooms caused massive fish kills in fish farms in Northern Norway in May 1991 and 2019. More than 14 500 tons of farmed salmon died in 2019. Cultures from both blooms were used in physiological experiments to investigate possible causes for the blooms. Growth experiments with varying salinity, temperature and irradiance in a facultative design were performed. Highest growth rates were obtained at temperatures 11-15 oC and salinities 25-30, and the tolerance range for growth were between 4-15 oC and salinities 20-34. Under optimal conditions, growth rates increased with irradiance (up to 100 µmol photons m-2 s-1). During the bloom in 2019, highest C. leadbeateri concentrations were found in waters with slightly reduced salinity (32-33) and sea surface temperatures around 7oC. Strains from the blooms in 1991 and 2019 were identical in the 18S rRNA gene. This ribotype appears to have a cold water-Arctic geographical distribution based on the metaPR2 metabarcoding datasets, whereas other ribotypes of C. leadbeateri in this dataset show a cosmopolitan or temperate-warm water distribution. We suggest that C. leadbeateri consists of several ribotypes with different growth preferences and that the toxic blooms in Northern Norway were formed by a ribotype adapted to cold waters with slightly reduced salinity and can tolerate rather high irradiances. Possible causes for the ichthyotoxic blooms will be discussed.

• Borgå, Katrine; McKinney, Melissa A.; Giebichenstein, Julia; Dinh, van Khuong; Gravelle, Amalie Marie Bårnås & Heuschele, Jan David [Show all 10 contributors for this article] (2023). The influence of climate change on accumulation and toxicity of pollutants in Arctic marine food webs. Full text in Research Archive
• Edvardsen, Bente (2023). On the track of causes for fish-killing algal blooms. Full text in Research Archive Show summary

  Harmful algal blooms (HABs) in marine, brackish and fresh waters resulting in fish-kills occur worldwide and may lead to great economic and ecological losses, as well as suffering for the fish. Farmed fish in pens and ponds are especially prone as they cannot escape from the blooms. Many ichthyotoxic blooms are sporadic events and the causes and triggering factors of these HABs are often poorly understood. Knowledge on the responsible algae and their physiology, ecology and environmental factors promoting their growth are required to understand these events. Bloom formation may also be linked to their toxicity through a relaxation of the top-down control from grazers, pathogens or competitors. We thus also need to understand how toxin production or toxicity are affected by various environmental factors to be able to understand causes of HABs. Knowledge about the responsible toxin(s) and their mode of action may however be limited and difficult to quantify. In this presentation I will compare ichthyotoxic haptophytes and look at similarities and differences in their bloom formation, ecology, physiology and toxicity in order to better understand causes for some of these blooms, especially of the little studied species Chrysochromulina leadbeateri.

• Garvang, Even Sletteng & Skogvoll, Vidar (2023). Under Kappa - #5 - The Flash - Raske dyr og tidrommet. [Radio]. Podcast. Full text in Research Archive
• Langbehn, Tom; Ljungström, Anna Jeja Gabriella; Fiksen, Øyvind; Aksnes, Dag; Kaartvedt, Stein & Jørgensen, Christian (2023). Model evidence for photic barriers to poleward range shifts. Full text in Research Archive
• Planque, Benjamin; Aarflot, Johanna Myrseth; Buttay, Lucie; Carroll, JoLynn; Fransner, Sara Filippa Krusmynta & Eide, Cecilie Hansen [Show all 17 contributors for this article] (2023). A standard protocol for describing the evaluation of ecological models. Full text in Research Archive
• Heimböck, Martin Paul; Lutier, Mathieu; Albini, Dania; Borgå, Katrine & Dinh, van Khuong (2023). Egg production as a stress-response in arctic copepod C. glacialis. Full text in Research Archive
• Heimböck, Martin Paul; Lutier, Mathieu; Albini, Dania; Borgå, Katrine & Dinh, van Khuong (2023). Contrasting effects of pyrene exposure on survival and reproduction of a key Arctic copepod Calanus glacialis. MSc Thesis. Full text in Research Archive
• Eliassen, Lasse Krøger; Garvang, Even Sletteng; Andersen, Tom; Engseth, Erik; Kristiansen, Kåre Andre & Wiik-Nielsen, Jannicke [Show all 7 contributors for this article] (2023). A parasite-copepod association and its effects on host pigmentation and lipids. Full text in Research Archive
• Larsen, Thomas ostenfeld; Wang, Xinhui; Fon, Mathias; Andersen, Aaron John Christian; Hansen, Per Juel & Uhlig, Silvio [Show all 8 contributors for this article] (2023). Insights into the chemistry of microalgal toxins involved in recent northern European fish killing events. Full text in Research Archive
• Garvang, Even Sletteng & Skogvoll, Vidar (2023). Under Kappa - #6 - Catwoman - Katter, og hvorfor de alltid lander på beina. [Radio]. Podcast. Full text in Research Archive
• Garvang, Even Sletteng & Skogvoll, Vidar (2023). Under Kappa - #4 - Supermann - Astrofysikk og romvesenbiologi. [Radio]. Podcast. Full text in Research Archive
• Delsett, Lene Liebe; Skogvoll, Vidar; Kline, Simon Hasselø & Jemterud, Torkild (2023). Abels tårn - Er det flest øyne eller føtter i verden? [Radio]. NRK P2. Full text in Research Archive
• Heuschele, Jan David; Lode, Torben; Bruserud, Hilde; Brochmann, Solveig; Dingstad, Trym Røil & Wolf, Raoul [Show all 7 contributors for this article] (2023). The population development of splash pool organisms under copper and predation risk exposure in field conditions. Full text in Research Archive
• Schultze, Sabrina; Langva, Hilde K.; Knudtzon, Nina Cathrine; Chatzigeorgiou, Marios; Rundberget, Jan Thomas & Brooks, Steven [Show all 11 contributors for this article] (2023). Increases in Terrestrial Dissolved Organic Matter Will Not Increase Feeding Related Uptake of a common Lipid Soluble Contaminant In coastal Filter Feeders. Full text in Research Archive
• Andersen, Ida Yasin; Bendiksen, Kristian; Slangsvold, Einar Lie; Skogvoll, Vidar & Garvang, Even Sletteng (2023). Studio 2 - Julenissen som superhelt. [Radio]. P2. Full text in Research Archive
• Kwasniewski, Slawomir; Altenburger, Andreas; Assmy, Philipp Kurt Wolf; Bluhm, Bodil Annikki Ulla Barbro; Dabrowska, Anna Maria & Edvardsen, Bente [Show all 25 contributors for this article] (2023). Biodiversity in the northern Barents Sea and adjacent Nansen Basin – towards an updated inventory. Full text in Research Archive Show summary

  Biodiversity patterns shape and drive ecosystem processes and functions in the global ocean. Given the changing climate and recent agreements to protect ocean regions, current estimates of biodiversity must be assembled. Here, we present new estimates and spatial patters of taxon richness from microbes to mammals from a shelf-to-basin transect in the northern Barents Sea and southern Nansen Basin from seasonal sampling in 2018-2022 by the Nansen Legacy project. We find that estimates of taxon richness are higher on the shelf than in the basin for pelagic protists, zooplankton, and benthic macrobenthos, nematodes, and prokaryotes, but not for sympagic protists. Taxon richness varied seasonally for pelagic prokaryotes, protists, and zooplankton, but little for sympagic meiofauna, benthic prokaryotes and macrobenthos. Unsurprisingly, taxon richness was generally highest for single-celled taxa. Taxon-rich groups included: sympagic diatoms; pelagic prokaryotes (e.g., Alphaproteobacteria), diatoms, dinoflagellates, copepods; and benthic prokaryotes (with abundant taxa, e.g., Candidatus nitrosopumilus and Woesia), nematodes, and polychaetes. Unexpectedly absent - though known from earlier studies - were, for example, nematodes in sea ice. Ironically, at top (and perhaps other) trophic levels species richness is likely to be enhanced regionally for some time, while losses of Arctic (endemic) species will impact global biodiversity, and potentially Arctic ecosystem functioning

• Skogvoll, Vidar; Garvang, Even Sletteng & Bremnes, Inge (2023). Under kappa - #19 - Black bolt - Stemmeteknikk, lyd og bråkete dyr med Inge bremnes. [Radio]. Podcast. Full text in Research Archive
• Marquardt, Miriam; Goraguer, Lucie Hélène Marie; Assmy, Philipp Kurt Wolf; Bluhm, Bodil Annikki Ulla Barbro; Patrohay, Evan & Aaboe, Signe [Show all 12 contributors for this article] (2023). Seasonal dynamics of sea ice protists and meiofauna in the northwestern Barents Sea in relation to sea ice properties. Full text in Research Archive Show summary

  The rapid decline of Arctic sea-ice including that in the Barents Sea makes understanding sympagic biology an urgent task. Seasonal ice sampling (2019-2022) as part of the Nansen Legacy project focused on ice biota composition and abundance in the bottom 30cm of Barents Sea ice in relation to ice properties. In December and May we sampled growing first-year ice, while in July and August melting, older sea ice dominated, overall agreeing with ice trajectories. Abiotic ice conditions and Chla varied strongly seasonally, while POC values were unexpectedly homogenous. Low ice biota abundances in March could be related to late ice formation resulting in a short time for biota to build up biomass. Pennate diatoms dominated the bottom ice algal communities in all seasons, with highest biomass in May. Outside May, small-sized flagellates were co-dominant. Overall, ice meiofauna was comprised of harpacticoid copepods, copepod nauplii and rotifers, foraminiferans and highly abundant ciliates. While melting ice had released ice algal biomass in July, abundance of secondary producers remained high, indicating different life history traits. Unexpectedly abundant communities occurred in December, further strengthened the notion of an active biota in the dark Arctic winter. The data demonstrated a strong and partly unexpected seasonality in the ice biota, indicating that changing timing of ice formation and melt will significantly impact composition and phenology of sympagic communities.

• Skogvoll, Vidar; Garvang, Even Sletteng & Andersen, Guro Lilledal (2023). Under Kappa - #15 - The Thing - Stein, dyr med skall og superharde materialer med Guro Lilledal Andersen. [Radio]. Podcast. Full text in Research Archive
• Skogvoll, Vidar; Garvang, Even Sletteng & Winnberg, Kirsti (2023). Under Kappa - #13 - Hell Cow - Kyr, blodsugende dyr og effektive fly med Kirsti Winnberg. [Radio]. Podcast. Full text in Research Archive
• Schultze, Sabrina; Langva, Hilde K.; Knudtzon, Nina Cathrine; Chatzigeorgiou, Marios; Rundberget, Jan Thomas & Brooks, Steven [Show all 11 contributors for this article] (2023). Terrestrial dissolved organic matter is not an efficent vector for lipohilic contaminants in filter feeders. Full text in Research Archive
• Skogvoll, Vidar; Garvang, Even Sletteng & Uggerud, Nora (2023). Under kappa - #11 - Scorpion - Syre, vannkanoner og skorpioner med Nora Uggerud. [Radio]. Podcast. Full text in Research Archive
• Andersen, Ida Yasin; Bendiksen, Kristian; Slangsvold, Einar Lie; Skogvoll, Vidar & Garvang, Even Sletteng (2023). Studio 2 - Fysikk og biologi i superheltfilmen The Flash. [Radio]. P2. Full text in Research Archive
• Fon, Mathias; Supraha, Luka; Andersen, Tom; Uhlig, Silvio & Edvardsen, Bente (2023). Using high-throughput techniques to understand the growth of the fish-killing haptophyte Chrysochromulina leadbeateri in northern Norway. Full text in Research Archive
• Jensen, Thomas Correll; Schartau, Ann Kristin; Majaneva, Markus; Veraart, A.J.; Hessen, Dag Olav & Eiler, Alexander [Show all 8 contributors for this article] (2023). Bird impacts on biological communities in Arctic ponds. Full text in Research Archive
• Samdal, Ingunn Anita; Uhlig, Silvio; Solhaug, Anita; Fon, Mathias; Gilbert, Dorothea & Ivanova, Lada [Show all 15 contributors for this article] (2023). Toxic microalgae in Norwegian waters - Uncovering fish-killing mechanisms of phytoplankton from Scandinavian waters. Full text in Research Archive
• Marquardt, Miriam; Goraguer, Lucie Hélène Marie; Assmy, Philipp; Bluhm, Bodil; Aaboe, Signe & Down, Emily [Show all 12 contributors for this article] (2023). Seasonal dynamics of sea ice protists and meiofauna in the Northern Barents Sea. Full text in Research Archive
• Marquardt, Miriam; Assmy, Philipp; Edvardsen, Bente; Goraguer, Lucie Hélène Marie; Gradinger, Rolf Rudolf & Patrohay, Evan [Show all 10 contributors for this article] (2023). Seasonal dynamics of sea ice protists and meiofauna in the northern Barents Sea. Full text in Research Archive Show summary

  The declining Arctic sea ice makes understanding sympagic biology a urgent task, including the Northern Barents Sea, which is highly influenced by ice loss and increased Atlantic inflow. A seasonal ice sampling effort (2019-2022) as part of the Nansen Legacy project focused on the poorly known ice biota composition and abundance in the bottom 30cm of Barents Sea ice in relation to season, hydrography and ice properties. We expected low abundances during the polar night and highest values during the spring prior to ice melt. From December and March, ice thickness increased while melting dominated in summer. Pennate diatoms, such as Navicula and Nitzschia spp., were dominating the bottom ice protist communities during all periods, while small-sized dinoflagellates were co-dominant. Ice meiofauna was comprised of harpacticoid copepods, copepod nauplii, rotifers, occasional visitors such as acoels and foraminiferans and highly abundant ciliates (50-90 %; total abundances). Surprisingly, active December communities occurred in higher than expected abundances. Low abundances in March could be related to later on-set of ice formation and reduced time for biota to establish. Maximum meiofauna abundances in May reflect a late spring bloom development. In August despite ice melting meiofauna abundances were still high. The data demonstrated a strong and partially unexpected seasonality in the ice biota, indicating that changing timing of ice formation and decay will significantly impact the current sea ice biology.

• Heuschele, Jan David; Lode, Torben; Bruserud, Hilde; Brochmann, Solveig; Dingstad, Trym R & Wolf, Raoul [Show all 7 contributors for this article] (2023). Development of splash pool populations under copper and predation risk exposure in field conditions. Full text in Research Archive
• Wahl, Andreas; Lie-Jensen, Anette Christensen & Kline, Simon Hasselø (2023). Jøss?! #136 - Zombieplankton, vettug grunn til å drikke tiss og drukningsdød i verdensrommet (Podcast). Full text in Research Archive
• Nowicki, Robynne; Borgå, Katrine; Gabrielsen, Geir Wing; Søreide, Janne & Varpe, Øystein (2023). Seasonal Dynamics of Body Condition and Energy Content of Polar Cod (Boreogadus saida). Full text in Research Archive
• Giebichenstein, Julia; Harju, Mikael; Varpe, Øystein; Gabrielsen, Geir Wing; Andersen, Tom & Borgå, Katrine (2023). Across the Seasons: Persistent Organic Pollutants in an Arctic Pelagic Food Web. Full text in Research Archive
• Vereide, Emilie Hernes; Jong, Karen de; Utne-Palm, Anne Christine; Titelman, Josefin; Browman, Howard & Mihaljevic, Marina [Show all 8 contributors for this article] (2023). ZoopSeis- Zooplankton og seismikk. Full text in Research Archive
• Chen, An; Fon, Mathias; Edvardsen, Bente; Uhlig, Silvio & Solhaug, Anita (2023). Evaluation of toxicity of the microagla Chrysochromulina leadbeateri using the Atlantis salmon gill epithelial cell line ASG-10. Full text in Research Archive
• Jensen, Thomas Correll; Schartau, Ann Kristin; Majaneva, Markus; Hessen, Dag Olav; Eiler, Alexander & Loonen, Maarten J.J.E. [Show all 7 contributors for this article] (2023). Bird impacts on biological communities in Arctic ponds – preliminary results. Full text in Research Archive
• Fagerlund, Carl Johan Ludwig; Jourdain, Eve Marie; Andvik, Clare Margaret; Yuan, Bo; Ruus, Anders & Borgå, Katrine (2023). Understanding mercury and chlorinated paraffins biomagnification by identifying dietary patterns in killer whales in Norway. Full text in Research Archive
• Vereide, Emilie Hernes; Jong, Karen de; Mihaljevic, Marina; Fields, David M.; Titelman, Josefin & Browman, Howard [Show all 9 contributors for this article] (2023). ZoopSeis- The effects of seismic surveys on zooplankton. Full text in Research Archive
• Andvik, Clare Margaret; Jourdain, Eve Marie; Ruus, Anders & Borgå, Katrine (2023). Effect of multiple stressors on Norwegian killer whales (MULTIWHALE). Full text in Research Archive
• Skogvoll, Vidar & Garvang, Even Sletteng (2023). REAL kino: Thor! Full text in Research Archive
• Opdal, Anders Martin Frugård; Andersen, Tom; Hessen, Dag Olav; Lindemann, Christian & Aksnes, Dag Lorents (2023). Tracking freshwater browning and coastal water darkening from boreal forests to the Arctic Ocean. Full text in Research Archive
• Dinh, van Khuong (2023). Science for use talk - Seasonal and climate change effects on pollution accumulation and effects in the Arctic marine food web. Full text in Research Archive
• Langangen, Øystein Ole Gahr & Durant, Joël (2023). Mass mortality and population dynamics of fish. Full text in Research Archive
• Dupont, Nicolas; Durant, Joël; Langangen, Øystein Ole Gahr & Stige, Leif Christian (2023). Survival of adult polar cod (Boreogadus saida) in the context of “borealization” of the Barents Sea. Full text in Research Archive
• Dupont, Nicolas; Durant, Joël; Langangen, Øystein Ole Gahr & Stige, Leif Christian (2023). Effects of abrupt ecological change on the Barents Sea Arctic food-web: predictions from a food-web state-space model. Full text in Research Archive
• Nowicki, Robynne; Borgå, Katrine; Gabrielsen, Geir Wing & Varpe, Øystein (2023). Exploring seasonal energetics of Barents Sea macrozooplankton and the impact of borealization. Full text in Research Archive
• Mariussen, Espen; Skuland, Tonje Schwach; Dahlman, Hans Jørgen; Låg, Marit & Øvrevik, Johan (2023). An Approach to Test Effects on Secondary Organs via Lung Cells Exposed at the Air Liquid Interphase. Annals of Work Exposures and Health. ISSN 2398-7308. 67(S1), p. i59–i59. Full text in Research Archive
• Saubrekka, Karoline; Vader, Anna; Supraha, Luka; Andersen, Tom & Edvardsen, Bente (2023). Diversity and Distribution of Arctic Protists in Pelagic and Sympagic Habitats in the Northern Barents Sea as Revealed by Metabarcoding. Full text in Research Archive
• Saubrekka, Karoline; Vader, Anna; Supraha, Luka & Edvardsen, Bente (2023). Diversity and distribution of Arctic protists in pelagic and sympagic habitats in the northern Barents Sea as revealed by metabarcoding. Full text in Research Archive Show summary

  Protists play crucial roles in the marine ecosystems and in a rapidly changing Arctic it is important to reveal who are there, when and where, for future research and management. The aim of this study was to describe and compare the composition of protist communities in sea ice and pelagic habitats from samples collected in the northern Barents Sea along a transect in August 2018 with low sea-ice extent and 2019 with high sea-ice extent. Metabarcoding targeting the 18S rRNA gene revealed 3682 unique amplicon sequence variants (ASVs), a proxy for species, and clear difference in ASV composition in ice and pelagic habitats. The pelagic community showed interannual differences. In 2018 the community was dominated by dinoflagellates and nano- and pico-plankton such as Micromonas polaris. In 2019 a community with more centric diatoms was observed at ice edge stations. Members of the class Chrysophyceae dominated in melt ponds, whereas communities within the ice were dominated by dinoflagellates and pennate diatoms. The community changed from top to bottom of the ice cores and the diversity was higher in thick than thin ice. Just below the ice, dinoflagellate ASVs dominated together with Phaeocystis. Our results indicate that protist communities are distinct and specialized by habitat. With further ocean warming, pelagic communities may shift towards smaller flagellates, and thinning of the sea ice may lead to a loss of habitats and diversity.

• Edvardsen, Bente; Supraha, Luka; Egge, Elianne Dunthorn & Saubrekka, Karoline (2023). Diversity and distribution of marine protists in the Arctic explored by a polyphasic approach. Full text in Research Archive
• Eikrem, Wenche; Vader, Anna; Hofgaard, Antje & Edvardsen, Bente (2023). Phytoplankton in the Arctic Ocean - Species Composition and Biomass during the Nansen Legacy Arctic basin cruise, 24 Aug-26 Sep 202. Full text in Research Archive Show summary

  At the southern-most station along the S-N transect, P7, the pelagic protist community was characterized by both high diversity and abundance. Large diatom species dominated the community, and large dinoflagellates and Phaeocystis pouchetii were also abundant. Moving north and into the ice, the protist community in the water column changed. Smaller organisms and heterotrophic species became more prominent. The larger diatom species became much scarcer but were still present. The community in the ice cores was dominated by pennate diatoms, but dinoflagellates and in particular the heterotrophic species were also abundant. In addition, green flagellates, cryptomonads, chrysophytes, and haptophytes were frequent. The sea-ice showed the highest chlorophyll-a values and had larger cells. In the melt ponds the salinity was low, but variable (2.8-5.7). The chlorophyll-a values there were low, and the species composition varied, and the taxa present were associated with brackish and freshwater as well as a benthic lifestyle.

• Opdal, Anders Martin Frugård; Lindemann, Christian; Fiksen, Øyvind; Hessen, Dag Olav; Andersen, Tom & Aksnes, Dag Lorents (2023). Tracking freshwater browning and coastal water darkening from boreal forests to the Arctic Ocean. Full text in Research Archive
• Andvik, Clare Margaret; Jourdain, Eve Marie; Borgen, Anders; Haug, Tore; Karoliussen, Richard & Borgå, Katrine (2023). Short, Medium and Long-chain Chlorinated Paraffins and Dechloranes in Marine Mammals from Norway. Full text in Research Archive
• Edvardsen, Bente (2023). Biodiversity of microalgae in Scandinavian marine waters. Full text in Research Archive
• Giebichenstein, Julia; Warner, Nicholas Alexander; Routti, Heli Anna Irmeli; Harju, Mikael; Varpe, Øystein & Andersen, Tom [Show all 8 contributors for this article] (2023). Emerging contaminant accumulation in an Arctic marine food web. Full text in Research Archive
• Andvik, Clare Margaret; Jourdain, Eve Marie; Ruus, Anders & Borgå, Katrine (2023). Effect of multiple stressors on Norwegian killer whales (MULTIWHALE). Full text in Research Archive
• Durant, Joël; Ono, Kotaro & Langangen, Øystein Ole Gahr (2023). Empirical evidence of non-linearity in the interaction between fish stocks in the Barents Sea. Full text in Research Archive Show summary

  The strength of species interactions can have a significant impact on population dynamics. Empirical estimates of interaction strength are often based on the assumption that the interaction strength is constant. Several fish species interact in the Barents Sea and their population dynamics are typically modelled under the assumption of constant interaction strength. However, interactions between species are often non-linear in marine ecosystems and this could fundamentally change our understanding of food webs’ functioning. Here, we present two examples of such nonlinear interactions in the Barents Sea, between cod Gadus morhua and capelin Mallotus villosus, and between cod and haddock Melanogrammus aeglefinus. Analysis of long survey time series in the Arcto-boreal Barents Sea within a state-space modelling framework showed that the effect of capelin on cod is not linear but varies with capelin abundance. Similarly, interactions between cod and haddock have changed over the past two decades due to rising ocean temperatures, altering the equilibrium abundances and the dynamics of the system. Our analyses demonstrate that long-term climate change in the Arcto-boreal system leads to differences in equilibrium conditions for species communities and demonstrates the importance of investigating nonlinearities in species interactions, leading to a better understanding of species communities and species assemblages.

• Thrane, Jan-Erik (2023). NIVA is frontrunner in the tech race - Modern and innovative methods for environmental monitoring. Full text in Research Archive
• Sjøtun, Kjersti; Fredriksen, Stein; Gabrielsen, Tove M.; Husa, Vivian; Goecke, Franz Ronald Saavedra & Gall, Line Le [Show all 9 contributors for this article] (2023). Mapping and DNA barcoding the brown algal diversity within the orders Ectocarpales, Ralfsiales and Sphacelariales in Norway. Full text in Research Archive
• Bekkby, Trine; Torstensen, Ragnhild Ryther Grimm; Grünfeld, Lars Andreas Holm; Gundersen, Hege; Fredriksen, Stein & Rinde, Eli [Show all 12 contributors for this article] (2023). Hanging gardens - do floating kelp farm communities resemble natural kelp forests? Full text in Research Archive Show summary

  The interest in seaweed cultivation is increasing globally, which requires knowledge of the potential effect of seaweed production on the marine environment, both negative and positive. We therefore wanted to study the fauna communities found in a kelp farm and compare these with what is found in natural kelp forests with the aim of finding out if a kelp farm ecosystem resembles that of natural kelp forests. The field work was conducted in north-western Norway, just before the kelp was harvested in the spring. Fauna traps were deployed and kelp plants scraped in the kelp farm (both in the sugar kelp, Saccharina latissima, and the winged kelp, Alaria esculenta, part), in natural sugar kelp, winged kelp and tangle kelp (Laminaria hyperborea) forests and in the water masses. The potential effect of the duration of the growth period of the farmed sugar kelp on the associated community was also analysed. The study shows that a kelp farm has lower taxa richness and fewer individuals than natural kelp forests, but indicates that the farm still has an ecological function as a habitat. However, the communities in the farm are more similar to the natural kelp forest surrounding the farm than with the natural kelp forest of similar species. The result from this study contributes with important knowledge of kelp farms ecological role in the marine environment, which is important both for today’s management and for the planned growth of the industry.

• Opdal, Anders Martin Frugård; Lindemann, Christian; Fiksen, Øyvind; Hessen, Dag Olav; Andersen, Tom & Aksnes, Dag Lorents (2023). Land use change and coastal water darkening drive synchronous dynamics in phytoplankton and fish phenology on centennial time scales. Full text in Research Archive
• Borgå, Katrine; McKinney, Melissa A.; Routti, Heli Anna Irmeli; Fernie, Kim J.; Giebichenstein, Julia & Hallanger, Ingeborg G. [Show all 7 contributors for this article] (2022). The influence of global climate change on accumulation and toxicity of persistent organic pollutants and chemicals of emerging concern in Arctic food webs. Full text in Research Archive
• Edvardsen, Bente (2022). Exploration of protist diversity and distribution in the ocean by a polyphasic approach. Full text in Research Archive
• Edvardsen, Bente (2022). Metabarcoding and Systematics of Protists in the Ocean to Understand Ecosystem Functioning. Full text in Research Archive
• Dupont, Nicolas; Durant, Joël; Langangen, Øystein Ole Gahr & Stige, Leif Christian (2022). Change in the Barents Sea Arctic food-web dynamic based on biotic and abiotic environmental factors. Full text in Research Archive
• Dinh, van Khuong; Titleman, Josefin; Søreide, Janne; Hylland, Ketil & Borgå, Katrine (2022). Long-Term Effects of Warming and Pyrene on Calanus hyperboreus. Full text in Research Archive
• Borgå, Katrine; McKinney, Melissa A.; Routti, Heli Anna Irmeli; Fernie, Kim J.; Giebichenstein, Julia & Hallanger, Ingeborg G. [Show all 7 contributors for this article] (2022). The influence of global climate change on accumulation and toxicity of persistent organic pollutants and chemicals of emerging concern in Arctic food webs. Full text in Research Archive
• Borgå, Katrine (2022). Hva gjør at spekkhoggerne blir stressa? [Radio]. Ekko i P2. Full text in Research Archive
• Garvang, Even Sletteng; Eliassen, Lasse Krøger; Titelman, Josefin & Andersen, Tom (2022). Modeling the parasites of copepods. Full text in Research Archive
• Garvang, Even Sletteng (2022). My master’s experience: parasites, tiny animals and nothing going as planned. Full text in Research Archive
• Eliassen, Lasse Krøger; Garvang, Even Sletteng; Andersen, Tom; Engseth, Erik; Kristiansen, Kåre Andre & Wiik-Nielsen, Jannicke [Show all 7 contributors for this article] (2022). The yellow-hyphal parasite in Calanus finmarchicus. Full text in Research Archive
• Gundersen, Madeleine S.; Morelan, Ian; Bakke, Ingrid; Andersen, Tom & Vadstein, Olav (2022). Disturbances increase selection – whereas stability promotes stochastic assembly in bacterial communities. Full text in Research Archive
• Angell, Thorvald; Eiler, Alexander & Stensrud, Eivind (2026). Changes at the Base of the Food Web in the Oslofjord and Skagerrak. Top predators as food web sentinels using DNA metabarcoding and stable isotope analysis. Universitetet i Oslo. Full text in Research Archive Show summary

  The coastal food webs of the Oslofjord and Skagerrak are undergoing alterations in structure, energy transfer, and basal organic matter (OM) sources due to multiple anthropogenic drivers, including eutrophication, increased terrestrial runoff, and climate change. These interacting pressures elevate the influx of terrestrial OM (tOM) and are associated with an increase in chromophoric dissolved OM (cDOM) to the coastal areas. As these allochthonous inputs increasingly exceed the autochthonous OM production, the resulting brownification alters the light attenuation regimes and thus drives the base of coastal ecosystems towards heterotrophic processes. Despite these documented biogeochemical shifts, the extent to which they disrupt the base of the food web and propagate upward through trophic interactions to the top predators remains poorly understood. Resolving how anthropogenic stressors restructure trophic pathways is also essential for predicting ecosystem responses to conservation and restoration strategies. To investigate how anthropogenic pressures have altered the coastal food web over the last two decades, dietary DNA metabarcoding was conducted on gut content from harbour seal (Phoca vitulina) and great cormorant (Phalacrocorax carbo), targeting secondary consumption with emphasis on the base of the food web. Two complementary gene markers were used: 18s rRNA V4 (Pirreda) to characterize the eukaryotic protist communities and COI (Leray-XT) to identify metazoan prey, including fish and invertebrates. To assess temporal shift in basal energy and organic matter sources, stable isotope analysis of top predator tissue was complemented with longterm monitoring data of Atlantic cod (Gadus morhua) and blue mussel (Mytilus edulis). These multiple approaches successfully characterized the food web from top predators down to the base of the food web. Although the findings revealed diet partitioning in the top predators primary consumption, reflecting different foraging strategies, they exhibit a strong overlap in the lower trophic levels and at the base of the food web. This suggests that the top predators are affected by the same bottom-up regime, rendering them mutually susceptible to the cascading effects of anthropogenic pressures, particularly increased terrestrial organic matter inputs. Finally, complementary isotopic data revealed a significant decrease in d 13C over the past 20 years, signaling a systemic shift in the coastal food web’s primary energy base toward allochthonous carbon sources.

• Eiler, Alexander; Riis-Pedersen, Christine; Hessen, Dag Olav & Minde, August Woldseth (2026). Under ice: The methane cycle in meromictic lakes during winter. Universitetet i Oslo. Full text in Research Archive Show summary

  Anthropogenic pressures and climate warming are increasingly driving freshwater ecosystems toward permanent stratification, yet the implications for the global carbon cycle remain poorly constrained. Meromictic lakes act as substantial reservoirs for dissolved greenhouse gases in their anoxic monimolimnia, but the efficiency of the chemocline in attenuating upward-diffusing methane (CH4) during winter ice- cover requires quantification. This study investigates depth-resolved CH4 and carbon dioxide (CO2) concentrations, alongside stable carbon isotope (δ13C) profiles, in two contrasting boreal meromictic lakes (euxinic Pollevannet and ferruginous Oppsjø) under winter conditions. High-resolution profiling revealed massive deep-water gas accumulation, with monimolimnetic CH4 concentrations exceeding 106 nM in both systems. In Pollevannet, δ13C − CH4 profiles exhibited a sharp 20‰ depletion across a 2-meter interval at the chemocline, providing isotopic evidence of a highly efficient microbial methane oxidation barrier. Furthermore, biogeochemical profiles suggest this barrier is reinforced by cryptic metabolic coupling; anoxygenic phototrophy at the low-light euxinic boundary likely regenerates sulfate (SO2−4 ), potentially subsidizing anaerobic methane oxidation in the underlying water. Oppsjø displayed a broader transition zone with more gradual isotopic shifts, reflecting its distinct ferruginous redox architecture. These findings demonstrate that stable winter stratification sustains a rigid, interdependent microbial bio-filter that effectively sequesters carbon in deep waters and decouples benthic methanogenesis from surface emissions.

• Mørch, Mikkel Martinussen; Hyvärinen, Olli Petteri; Eiler, Alexander; Werner, Even; Gagnon, Karine & Thormar, Jonas (2026). Biodiversity patterns and blue carbon characteristics of Zostera marina meadows in the Oslofjord. Universitet i Oslo. Full text in Research Archive Show summary

  Seagrass meadows are coastal foundation habitats that support biodiversity and store organic carbon in sediments, a process often referred to as blue carbon storage. However, both biodiversity and sediment carbon storage can vary strongly among meadows, and it remains unclear how local meadow structure, hydrodynamic exposure, organic-matter sources, and associated fauna interact in temperate eelgrass systems. This thesis investigated biodiversity and blue carbon characteristics of Zostera marina meadows in the Oslofjord, Norway. The study combined two complementary approaches: citizen-science-based environmental DNA (eDNA) water sampling across eelgrass meadows and seasons, and researcher-led field sampling at three meadows along an inner-outer Oslofjord gradient. The field-sampled meadows represented contrasting coastal settings: an inner-fjord meadow at Fornebu, a sheltered meadow near Sætre/Sandspollen, and a more wave- exposed outer-fjord meadow at Holmestrand. The water eDNA dataset provided broad spatial and seasonal coverage, but ecological interpretation was limited by uneven sampling and read-depth loss after filtering. After taxonomic partitioning of the cytochrome c oxidase I (COI) metabarcoding dataset, only 20.5% of reads were retained as faunal reads, while 79.5% were classified as non-faunal reads. The retained faunal water eDNA dataset did not show clear winter-spring or Oslofjord-section structure. Instead, it contained a mixed coastal signal, including pelagic planktonic taxa and benthic or soft-sediment-associated taxa. In contrast, the non-faunal fraction showed clearer winter-spring structuring, largely associated with microalgal and protist groups. This indicates that broad COI water eDNA can capture useful biodiversity signals, but also that faunal and non-faunal datasets should be separated before ecological interpretation. The strongest ecological patterns were found in the field-measured meadows. The sheltered Sætre/Sandspollen meadow had continuous eelgrass cover, low sediment bulk density, high and consistent organic carbon stocks, and the highest apparent seagrass-like carbon contribution. The more wave- exposed Holmestrand meadow was patchier and had higher bulk density, lower organic carbon stocks, and the lowest apparent seagrass-like carbon contribution. The inner-fjord Fornebu meadow had intermediate sediment carbon stock, bulk density, and apparent seagrass-like carbon contribution, but showed greater within-meadow variability. Stable isotope composition supported these meadow-level differences and indicated variation in both carbon-source characteristics and assimilated nitrogen among meadows. Benthic eDNA showed clear separation between seagrass-blade epifaunal communities and sediment-core infaunal communities. Infaunal communities were most strongly associated with sedimentary gradients and were dominated by sediment-associated annelids, including lugworms and other ii taxa linked to deposit feeding, burrowing, sediment reworking, and bioirrigation. In contrast, the epifaunal signal was dominated more strongly by sessile or surface-associated taxa, including barnacles, bryozoans, and hydrozoans, rather than by mobile mesograzers. Overall, this thesis shows that eelgrass meadows in the Oslofjord can differ substantially in meadow structure, sediment carbon characteristics, stable isotope composition, and associated benthic fauna. The results support a descriptive interpretation in which blue-carbon characteristics and benthic biodiversity vary together at local meadow scale, particularly through the association between sediment conditions and infaunal community structure. Broader inference about Oslofjord-wide seasonal biodiversity patterns will require more balanced repeated sampling but the study demonstrates the value of combining citizen-science water eDNA with targeted field measurements when assessing biodiversity and blue carbon in eelgrass meadows.

• Negård, Jesper Nilsen; Hyvärinen, Olli Petteri & Eiler, Alexander (2025). Characterization of the Carbon Export Potential of Commercially Important Fish Species in the Oslofjord. Universitetet i Oslo. Full text in Research Archive
• Klöcker, Antonia; Junge, Claudia; Queiroz, Nuno; Vihtakari, Mikko & Langangen, Øystein Ole Gahr (2025). On the move: The movement ecology of sharks in high-latitude waters and Beyond. Universitetet i Oslo. Full text in Research Archive Show summary

  Animal movement is a pervasive phenomenon that shapes and connects ecosystems. In the ocean, the movements of apex and mesopredators like sharks play a vital role in structuring the distribution and behaviour of lower trophic Levels and maintaining habitat connectivity both vertically and horizontally. However, their life-history traits and often high mobility make sharks particularly vulnerable to human-induced threats such as overfishing, habitat degradation, and climate change. Understanding where, when, how, and why sharks move is essential for developing effective and adaptive management strategies to ensure their long-term survival. This dissertation explored the movement ecology of two ecologically distinct shark species occurring in Norwegian waters: the bentho-pelagic, mesopredatory spurdog and the pelagic, plankton-feeding basking shark. Using satellite telemetry, this work examined both the vertical and horizontal dimensions of movement and habitat use across different seasons and environments. Beyond characterizing spatiotemporal movement patterns, this work investigated potential internal and external drivers, including pregnancy, morphological adaptations, as well as physical and biological resource availability and distribution, to gain insights into the underlying mechanisms of shark movement. Paper I examined seasonal habitat use and vertical movement patterns of 19 pregnant spurdogs in Norwegian fjords. The study revealed consistent diel vertical migration and deep-water use in winter and spring, with individuals shifting to shallower, warmer waters and reducing diel vertical migration in summer and autumn. Complementary seasonal variations in likely foraging-related activity bursts suggested winter movements were primarily foraging-driven, whereas behavioural thermoregulation may have dominated before parturition later in the year. Paper II assessed the potential for regional endothermy in basking sharks, a trait that allows a few cold-adapted fast-swimming pelagic fish like the porbeagle to retain heat in specific body regions. Contrary to expectations, a comparative morphological analysis confirmed the absence of red muscle endothermy in basking sharks. Instead, it revealed vascular arrangements that suggest cranial and, notably, visceral endothermy in the species. Together with partial red muscle internalization and its large body size, these adaptations likely facilitate an active lifestyle in cold-water environments. Paper III investigated habitat-dependent vertical movement in two basking Sharks across broad thermal, spatial, and temporal scales. Tracked individuals utilized waters with previously unrecorded low temperatures, both in the short- and longterm, likely facilitated by the morphological adaptations identified in Paper II. Further, the tracked individuals exhibited distinct vertical movement patterns in response to the local environment. The strong association with isolumes, thermoclines, bathymetry, and bioluminescent layers indicated that basking sharks actively track prey across diverse habitats. Paper IV analyzed the horizontal movements of 13 high-latitude basking Sharks throughout the annual cycle, documenting large-scale return migrations between areas of summer residency along the Norwegian Shelf and lower-latitude oceanic waters in the North Atlantic occupied during winter and spring. Their absence in known high-use areas at intermediate latitudes (i.e., UK and Ireland) and more extensive latitudinal migrations compared to their lower-latitude counterparts in the Northeast Atlantic suggest a distinct migration strategy amongst these ‘boreal’ individuals, likely driven by pronounced seasonal fluctuations in resource availability. Collectively, these studies provide new insights into the movement ecology of spurdog and basking sharks at the high-latitude edge of their distribution. The findings highlight the value of long-term, high-resolution telemetry and biologging in understanding drivers that enable these mobile predators to navigate complex and dynamic ocean environments. With ongoing technological advances, the rise of big data approaches, and the adoption of more integrated and open science practices, movement ecology is poised to evolve into a more mechanistic and predictive discipline. As anthropogenic pressures intensify, including the accelerating Atlantification in the Arctic, this transformation will be crucial for developing adaptive, evidence-based management strategies to safeguard these vulnerable ocean sentinels – now and in the future.

• Sildever, Sirje; Edvardsen, Bente; Egge, Elianne Dunthorn; Engesmo, Anette; Harðardóttir, Sara & Jacobsen, Ása [Show all 25 contributors for this article] (2025). Reliable environmental DNA detection of planktonic biodiversity: Minimum sample volume for DNA metabarcoding. Nordic Council of Ministers. ISSN 9789289381468. doi: 10.6027/temanord2025-509. Full text in Research Archive Show summary

  Environmental DNA (eDNA)-based detection has become an attractive method for determining biodiversity as it can provide more detailed information compared to traditional morphology-based approaches. This is especially relevant for targeting overall biodiversity or screening for the presence of harmful algal bloom (HAB) species. However, despite the availability of several general guidelines, the workflow for marine environments has yet to be standardised. This lack of standardisation complicates the comparison between samples across different monitoring programmes and projects. This project focused on the first step of the workflow – determining and standardising the minimum reliable sample volume needed to detect phytoplankton diversity under various environmental and biological conditions. A study and a workshop were conducted to test different sample volumes (1000 mL, 500 mL, 200 mL, and 20 mL), using samples collected from the Baltic and North Seas and northwestern Atlantic Ocean under various environmental conditions. Across the studied samples, 200 mL was identified as a sufficient sample volume to detect various species across the different volumes tested. This result represents an important first step towards standardising the eDNA-based approach and incorporating it into routine monitoring. Furthermore, the results of this project are expected to contribute to reducing the time and resources required for monitoring.

• Fon, Mathias; Edvardsen, Bente; Solhaug, Anita; Uhlig, Silvio; Ivanova, Lada & Andersen, Tom (2025). Insight into the growth, toxicity and toxins of the fish-killing haptophyte Chrysochromulina leadbeateri. University of Oslo (UiO). Full text in Research Archive
• Vereide, Emilie Hernes; Jong, Karen de; Palm, Anne Christine Utne; Agersted, Mette Dalgaard & Titelman, Josefin (2024). The Effects of Seismic Surveys on Marine Zooplankton. Universitetet i Oslo. Full text in Research Archive Show summary

  Anthropogenic underwater noise, such as boat noise, pile driving, or seismic surveys, is an increasing source of ocean pollution and poses a potential threat to marine life. Seismic surveys may negatively impact marine mammals and fish. However, little is known about the effects of zooplankton. Zooplankton are essential to marine ecosystems, transferring energy from lower to higher trophic levels and playing an important part in the carbon cycle. This work investigates the impact of seismic surveys on zooplankton, combining laboratory and field work and examining different species, developmental stages, and effects. The thesis shows that seismic airguns have a limited impact on zooplankton, with variations influenced by species, exposure conditions, and study design. While certain zooplankton taxa may experience increased mortality rates and behavioral changes, others display minimal effects. Additionally, the thesis underscores the harmful impact of rapid pressure drops associated with airgun exposure on zooplankton, underscoring the variability in how different taxa respond to various stressors. Furthermore, it highlights the importance of considering broader environmental contexts and recognizing the potential impact on other organisms when assessing the effects of anthropogenic underwater noise on marine ecosystems.

• Markova, Yana; Heuschele, Jan David & Striebel, Maren (2024). Copepods and Beyond: Spatio-Temporal Variability and Environmental Drivers of the Nearshore Zooplankton Community in the Oslofjord. University of Oldenburg. Full text in Research Archive
• Engseth, Erik; Titelman, Josefin & Andersen, Tom (2024). Constructing a conceptual food web of Oslofjord zooplankton using stable isotope analysis. Universitetet i Oslo. Full text in Research Archive
• Skari, Andrea Emilie Thorstensen; Dinh, van Khuong; Lutier, Mathieu; Konestabo, Heidi Sjursen & Borgå, Katrine (2024). Effect of global changes on marine copepods: Influence of pyrene or salinity on thermal tipping points. Universitetet i Oslo. Full text in Research Archive Show summary

  The ocean is warming at a rate unprecedented over the past twenty thousand years, and extreme warming events are increasing in frequency, duration, and intensity. This could surpass the thermal tolerance thresholds of marine species, tipping points that, when exceeded, can lead to abrupt and irreversible consequences. At the same time, the intensification of extreme weather events and anthropogenic activities increase the exposure of marine organisms to contaminants such as polycyclic aromatic hydrocarbons (PAHs) and to decreasing salinities. As organisms are simultaneously exposed to multiple stressors in their natural environment, it is therefore crucial to identify the effects these stressors have when combined to project their future in a changing world. The present study investigated how the PAH pyrene or decreasing salinity affect thermal tipping points of coastal marine copepods. Copepods are key planktonic organisms in marine ecosystems due to their essential role in energy transfer in the food web. The first experiment aimed to determine how oil contamination alters thermal tipping points of Aetideopsis sp. copepods. As a proxy for oil, the copepods were exposed to the PAH pyrene, at five concentrations and seven temperatures for ten days. The second experiment aimed to determine how decreasing salinities alters thermal tipping points of Calanus sp. copepods. The copepods were exposed to five decreasing salinities at five temperatures for eight days. Copepods for both experiments were collected in the Oslofjord, Norway, and survival was checked every day during the experiments. Both Aetideopsis sp. and Calanus sp. had thermal tipping points within environmentally relevant temperatures, between 13 °C and 16 °C for Aetideopsis sp. and between 14 °C and 18 °C for Calanus sp. Although pyrene did not affect thermal tipping points of Aetideopsis sp., it significantly decreased survival at the highest concentration of 200 nM. Decreasing salinity decreased the thermal tipping points of Calanus sp. at 23 PSU and 29 PSU, both environmentally relevant salinities. These findings suggest that the thermal niche of coastal marine copepods, already sensitive to pollutants such as pyrene, can be narrowed by decreasing salinities. This could ultimately have severe consequences on the ecological niches and distributions of copepod species and highlights the importance of determining tipping points in a multiple stressor context.

• Reitzel, Helene; Edvardsen, Bente; Šupraha, Luka & Heuschele, Jan David (2023). The ichthyotoxic algae Chrysochromulina leadbeateri – an investigation into favorable conditions for growth and toxicity. Universitetet i Oslo. Full text in Research Archive Show summary

  Harmful algal blooms can be devastating to local ecosystems as well as have major impacts on economy and aquaculture. Chrysochromulina leadbeateri caused the death of an estimated seven and a half million farmed salmon in 2019, and the cause of this bloom is still unknown. While the growth and toxicity of other toxic prymnesiophytes have been examined, we still know little about optimal conditions for growth and toxicity of Chrysochromulina leadbeateri. In this thesis I have examined the growth of C. leadbeateri in controlled conditions, and how different salinities and temperatures affects the growth rate. I also examined the toxicity and whether or not I could induce it in a laboratory setting, and whether phosphorous limitation or other temperatures or salinities could play a role. I conducted three growth experiments. The first to establish a relationship between cell density and chlorophyll a fluorescence measurements. The second and third growth experiments were used to establish how different temperatures and salinities affected the strains of C. leadbeateri and how the different conditions affected growth rate as well as establish tolerance limits. Low temperatures and low salinities seemed to affect growth negatively, while optimum growth conditions were at 15°C and a salinity between 25 and 30. I recommend that the growth experiments are replicated with the inclusion of higher temperatures to establish where the upper temperature limit is, as well as repeat the temperatures used to get a better understanding of growth at 11°C as the equipment here had some flaws. I performed three Artemia bioassay experiments. The first showed that the cultures did not become more toxic after growing in phosphorous limited conditions compared to those that hadn’t. The second and third Artemia bioassay experiments were performed to see whether temperature or salinity played a role in inducing toxicity, as well as where in the growth phase the cultures were. Cultures that were in their stationary stage were toxic to Artemia nauplii, and this seemed to play a larger role in inducing toxicity than temperature or salinity.

• Tran, Jacquelynn Phuong-Vy; Edvardsen, Bente; Fon, Mathias; Heuschele, Jan David & Titelman, Josefin (2023). When hungry meets harmful: investigating the toxic relationship between haptophytes and copepods. Predatory induced defenses in Chrysochromulina leadbeateri. Universitetet i Oslo. Full text in Research Archive Show summary

  Harmful algal blooms are a recurring phenomenon all around the world, causing devastating effects including massive fish kills. A bloom of the toxic haptophyte, Chrysochromulina leadbeateri, in Northern Norway during May-June 2019 was the largest bloom ever recorded in that area causing massive mortalities of farmed salmon. While past C. leadbeateri blooms are known to cause such damage, relatively little is known about this toxic haptophyte, compared to other species. Some studies have investigated the bloom dynamics and abiotic factors influencing its toxicity, but little is known about the biotic influences. In particular, the predator-prey interactions with copepods. Past studies have found that when other species are directly exposed to predation threats (e.g. herbivorous copepods), the algae will respond by inducing and/or increasing toxicity potential as a defense mechanism. Those studies have focused on toxic diatoms and dinoflagellates producing shellfish toxins, but the potential for fish-killing algae to be influenced by predation pressure remains to be explored. In this thesis, I examined the biotic interactions between the toxic C. leadbeateri and the grazing Acartia sp. copepods. I first conducted a series of 3-day tolerance experiments, exposing Acartia sp. to different C. leadbeateri concentrations to answer: What is the threshold C. leadbeateri concentration that Acartia sp. can maintain survival and grazing? Then I conducted 3-day induction experiments, exposing C. leadbeateri to varying levels of grazing pressure, and in vitro tests using two fish cell lines to measure this potential grazing-induced toxicity to answer: Does the presence of copepod grazers affect toxicity in the ichthyotoxic haptophyte C. leadbeateri? Through the initial tolerance experiments, I determined that ca. 5 x 104 cells ml-1 of C. leadbeateri was the threshold concentration that enough Acartia sp. could survive and maintain feeding for the later toxicity induction experiments. Acartia sp. short-term tolerance to direct exposure to C. leadbeateri appeared to be concentration and time-dependent since the toxins need to be taken up by Acartia sp. to cause mortalities. Copepod grazing habits observed during the induction experiment appeared unaffected when C. leadbeateri was the only food source, as evidenced by fecal pellet production. However to accurately determine the effects of grazing on C. leadbeateri, future studies should observe grazing periodically with Acartia sp. exposed to different C. leadbeateri concentrations and non-toxic food alternatives. I examined whether the toxicity of C. leadbeateri was influenced by the presence of grazing copepods using in vitro tests on two fish (Rainbow trout and Atlantic salmon) cell lines to measure cell viability and light microscopy to look at morphological changes. I created different concentrations of algal extracts from crude C. leadbeateri material exposed to varying grazing levels. The different extracts were exposed to the gill cells in a microplate-based assay for 24 hours and at the endpoint, cell viability was measured using Alamar blue as an indicator dye. It seems that while increasing algal extract concentration decreases cell viability, extract made from C. leadbeateri exposed to increasing grazing pressure does not increase the negative effects on cell viability. The light micrographs of the gill cells suggest the same, but with some inclination that grazing pressure does affect some toxicity potential in C. leadbeateri. Unfortunately, with the lack of more independent trials, there is no statistical analyses to back up these claims. More experiments would allow for proper analyses and a potentially more conclusive statement about the relationship between copepod grazing and the toxicity potential of C. leadbeateri. This thesis can be used as a starting point for future research on the dynamics between toxic haptophytes and their copepod grazers.

• Husson, Berengere; Eriksen, Elena; Jentoft, Sissel; Boge, Erling; Borgå, Katrine & Chierici, Melissa [Show all 36 contributors for this article] (2023). Polar cod connectivity cruise 2022 Cruise Report. UiT Norges arktiske universitet. doi: 10.7557/nlrs.6944. Full text in Research Archive
• Carroll, JoLynn; Skeie, Geir Morten; Vikebø, Frode Bendiksen; Broch, Ole Jacob; Frøysa, Håvard Guldbrandsen & Howell, Daniel [Show all 12 contributors for this article] (2023). SYMBIOSES III: Final report. SYMBIOSES - Advancing simulation technologies for ecosystem-based assessment of major oil spills in ecologically sensitive and environmentally challenging areas. Full text in Research Archive
• Ruus, Anders; Grung, Merete; Jartun, Morten; Bæk, Kine; Rundberget, Thomas & Beylich, Bjørnar [Show all 10 contributors for this article] (2023). Environmental Contaminants in an Urban Fjord, 2022. Norsk institutt for vannforskning (NIVA). ISSN 9788257776091. Full text in Research Archive Show summary

  This report presents data from the second year of a new 5-year period of the Urban Fjord programme. The programme started in 2013 and has since been altered/advanced. In 2022 the programme covers sampling and analyses of sediment, polychaetes, krill, shrimps, blue mussels, herring, cod, eider, and herring gull from the Inner Oslofjord. In addition, samples of Harbour seals from the Outer Oslofjord are analysed. A total of ~300 single compounds/isomers were analysed, and frequent detection was found of certain PFAS compounds (such as PFOS) in most matrices, certain QACs in sediment, MCCPs in most matrices (also SCCPs in birds and seals, as well as LCCPs in seals), D5 (siloxane) in all matrices, certain PBDEs (such as BDE 100) in most matrices, PCBs in all matrices, BCPS (phenolic) in seals and certain metals in all matrices. Biomagnification was observed for 28 PCB congeners and 6 PBDEs (lipid wt. basis). Furthermore, biomagnification was observed for 5 PFAS compounds, as well as for the metals As, Ag and Hg (wet wt. basis).

• Nilsen, Ina; Eide, Cecilie Hansen; Olsen, Are; Langangen, Øystein Ole Gahr & Kaplan, Isaac (2023). Dealing with uncertainty in ecosystem models along three axes; resolution, forcing and projections. Universitetet i Bergen. ISSN 9788230843871. Full text in Research Archive Show summary

  With the imminent threat of climate change, there is an urgent need to understand how warmer temperatures will affect marine ecosystems. Models provide the best tools to study the future, but although great efforts have been made to understand the impacts of warming temperatures, there is still large uncertainties related to the model projections. The uncertainties can arise from structural uncertainty of the ecosystem model, uncertainties regarding climate projections, or uncertainties related to how species will respond to future climate changes. In this thesis, we therefore apply ecosystem models of varying complexity, climate models of varying resolution and climate projections under various emission scenarios to understand and quantify uncertainty. By assessing the uncertainty, we highlight consistent results that suggest higher confidence, and areas where differences in the results suggest that more research is needed. The results from this thesis are divided into three research papers. The first paper deals with structural uncertainty regarding model complexity, as we explore the role of Northeast Atlantic cod (Gadus Morhua) in the Barents Sea food web by using a multi-model approach. We apply two ecosystem models of different complexity; the minimalistic Gompertz model and the highly complex Atlantis model, to study how capelin and polar cod respond to changing levels of cod. We highlight consistent results across the models and identify diverging results due to differences in spatial structure and number of foodweb components, and conclude that for fishery management purposes, the two models can complement each other. The second paper deals with uncertainty regarding the resolution of climate projections used to force ecosystem models, where we apply physics (temperature, salinity, volume transport and sea ice) from a regional model (Nemo-NAA10km) and its driving global climate model (NorESM2) to the Nordic and Barents Seas Atlantis ecosystem model (NoBa). We found that few higher trophic level (TL>3) species were affected by using forcing from a global versus a regional model, and there was a general agreement in future biomass trends and distribution patterns. Yet, our results showed how a slight difference in temperature can have dramatic consequences for specific species and demonstrate that species projection uncertainty could arise from poor representation of the physical forcing, as well as due to uncertainty in the ecosystem model parameterization. In the third and final paper, we deal with the uncertainty regarding ecosystem responses to future climate changes. We apply physics from three different climate projections (SPP1-2.6, SSP2-4.5 and SSP5-8.5) to study the impact of rising temperatures in the Nordic and Barents Seas using NoBa. To account for uncertainty in the response of phytoplankton and zooplankton to future climate change, we included variation in phyto- and zooplankton growth levels. We identify potential winners and losers in a warming climate and focus on the underlying mechanisms that drives the changes in the model, including spatial differences, thermal tolerance, and species interactions. Through our work we have demonstrated the value of using ecosystem models of varying complexity, climate models of varying resolution and climate projections under various emission scenarios to quantify uncertainty regarding model projections. By investigating uncertainty along these three axes, we learn more about the models and the mechanisms that drives the changes and provide valuable insight for management and future ecosystem studies.

• Walbækken, Hanna Myhre; Eikrem, Wenche; Edvardsen, Bente; Saubrekka, Karoline & Hofgaard, Antje (2023). Dinoflagellate diversity in the Barents Sea: a comparative identification analysis. Universitetet i Oslo. Full text in Research Archive
• Dankel, Eli; Supraha, Luka; Edvardsen, Bente; Eikrem, Wenche & Saubrekka, Karoline (2023). Arktiske kalkflagellater: et morfologisk og molekylært dypdykk i det nordlige Barentshavet. Universitetet i Oslo. Full text in Research Archive Show summary

  Oppblomstringer av kalkflagellater utgjør et viktig fundament for næringskjeden i Barentshavet. Fjernanalyse med satellittbilder har de siste tiårene dokumentert at denne oppblomstringen beveger seg nordover i takt med økende klimaendringer. Det er likevel fortsatt uvisst hva som skjer på artsnivå. Å forstå hvordan forekomsten til den enkelte art forandrer seg i møte med endrede miljøbetingelser, som redusert is og økende temperatur, gjør at man enklere kan forutse hvordan fytoplanktonsamfunnet vil respondere på et fremtidig, varmere Arktis. For denne oppgaven ble det hentet inn vannprøver fra syv stasjoner på et sør-nord-transekt i Barentshavet i august 2018 og 2019 under tokt i regi av forskningsprosjektet Arven etter Nansen (AeN). 2018 var globalt et av de varmeste årene på mange tiår, og Barentshavet var dermed isfritt den sommeren. I 2019 derimot var større deler av Barentshavet dekket av is. Prøver tatt for både svepeelektronmikroskopi (scanning electron microscopy, forkortet «SEM») og metastrekkoding (metabarcoding) ble brukt i oppgaven slik at resultatene fra metodene kunne sammenlignes. Formålet med SEM var å utføre både en kvalitativ og kvantitativ analyse av kalkflagellater. Metastrekkoding ble brukt til sekvensering av 18S rRNA-genet. I SEM fant jeg i prøvene fra 2018 Emiliania huxleyi, Coccolithus pelagicus, Papposphaera sarion, Papposphaera arctica, Wigwamma annulifera og Porsildia acerviphora. Utenom Coccolithus pelagicus og Wigwamma annulifera, ble de samme artene funnet i 2019. I tillegg ble Syracosphaera Marginiporata funnet i prøver fra et AeN-tokt i november-desember 2019. Artene fra 2018 var hovedsakelig til stede på den sørligste stasjonen i transektet, mens artene fra 2019 generelt ble funnet på flere forskjellige stasjoner. Fra metastrekkoding ble det registrert 13 OTUer (Operational Taxonomic Units) som er bestemt til kalkflagellat-taksa. Ettersom det stort sett mangler referansesekvenser for arktiske kalkflagellater, ble de fleste OTUene kun klassifisert til klasse eller orden. OTUene var for det meste til stede i prøvene fra den sørligste, og de to nordligste stasjonene. Det ble ikke observert et nevneverdig mønster i sammenheng med isdekket. Det ble derimot både for SEM og metastrekkoding observert at de fleste artene var til stede på stasjoner som i ulik grad ble påvirket av Den nordatlantiske havstrømmen. Resultatene er likevel ikke holdbare nok til å trekke en konklusjon om hvordan kalkflagellatsamfunnet i Barentshavet vil se ut i fremtiden. Ettersom de fleste OTUene viste lav taksonomisk oppløsning, og alle celler funnet i SEM ble bestemt til artsnivå, anbefaler jeg at SEM forblir den foretrukne metoden for kvalitativ og kvantitativ analyse av kalkflagellater.

• Edvardsen, Bente; Gryn, Khrystyna; Šupraha, Luka; Eikrem, Wenche & Saubrekka, Karoline (2023). Biodiversity and distribution of Arctic phytoplankton and ice algae. Universitetet i Oslo. Full text in Research Archive
• Røsbak, Silje K.; Edvardsen, Bente; Eiler, Alexander; Saubrekka, Karoline & Fon, Mathias (2023). Mikrobielt samfunn i kulturer av Chrysochromulina leadbeateri og relaterte svepeflagellater, undersøkt med metastrekkoding. Universitetet i Oslo. Full text in Research Archive Show summary

  Skadelige marine algeoppblomstringer er et tilbakevendende problem over hele verden, der skadene har en påvirkning på økosystemer og lokal økonomi. Chrysochromulina leadbeateri var årsak til en massiv fiskedød i 2019, men mekanismene bak denne oppblomstringen er fortsatt ukjent. Målet med oppgaven var å undersøke bakteriediversiteten i kulturer av den fiske-giftige Chrysochromulina leadbeateri, og sammenligne denne mot andre beslektede svepeflagellater, både hos potensielt giftige og ikke-giftige arter. I tillegg til dette ble bakteriediversiteten av mikrobiomet mellom fastsittende bakterier på algecellene og frittlevende bakterier i kultur undersøkt. I denne oppgaven ble det prokaryote mikrobiomet i kulturer av tre stammer av Chryochromulina leadbeateri og 6 stammer av beslektede svepeflagellatarter analysert. Dette ble gjort ved metastrekkoding av det ribosomale 16S rRNA-genet. Det ble påvist et mangfoldig mikrobiom der hele bakteriedatasettet inneholdt 3 rekker, 14 ordener og 53 slekter. Bakteriesamfunnets sammensetning bestod hovedsakelig av medlemmer i rekken Proteobacteria etterfulgt av medlemmer av rekken Bacteroidota, og kun noen få ASVer i rekken Actinobacteria. Av de 14 ordenene var Rhodobacterales, Flavobacteriales, Caulobacterales, Rhiszobiales og Cytophagales de mest vanlige. Av de 53 slektene var Marivita (Rhodobacterales) den mest abundante, etterfulgt av Roseovarius (Rhodobacterales), Jannaschia (Rhodobacterales), Hoefla (Rhizobiales), Seohaeicola (Rhodobacterales), Hyphomonas (Rhodobacterales) og Sulfitobacter (Rhodobacterales). Taksonomisk fordeling av bakterieslekter mellom de potensielt giftige og ikke-giftige svepeflagellatene viste forskjeller, der de potensielt giftige hadde flest unike identifiserte bakterieslekter. Når det gjelder alfadiversitet (forskjeller innad i et samfunn) viser de to gruppene derimot ingen store forskjeller i mikrobiomet. Det ble funnet en svak signifikant sammenheng i mikrobiomets betadiversitet (forskjeller mellom samfunn) mellom kulturer av potensielt giftige og ikke-giftige svepeflagellater, der svepeflagellatens giftighet innen slekt hadde en svak effekt i denne studien. I tillegg viste slekten til svepeflagellaten til å ha en signifikant betydning for hvilke bakteriearter som ble funnet i algekulturer. Ved en sammenligning av fordelingen av bakterieslekter som er fastsittende til algecellen og frittlevende i algekultur, deler de to gruppene 80 % av bakterieslektene, og har dermed høy likhet. De frittlevende bakteriene har høyest antall ASVer, noe som indikerer at de fleste bakterie-typene lever fritt i kultur. Dette vises også ved de statistiske analysene, der alfadiversiteten for de frittlevende bakteriene i kultur har et signifikant rikere mikrobiom i forhold til fastsittende bakterier til algecellen. Betadiversiteten mellom fastsittende og frittlevende bakterier viser derimot ingen signifikante forskjeller, som vil si at mikrobiom-sammensetningen ikke kan forklares ut ifra om det er fastsittende på algecellene eller frittlevende i kultur.

• Mariussen, Espen; Alexander, Jan; Dahl, Lisbeth; Kvalem, Helen Engelstad; Olsen, Ann-Karin Hardie & Schlabach, Martin [Show all 11 contributors for this article] (2023). Protocol for risk assessment of grilled and barbequed food. Norwegian Scientific Committee for Food and Environment . Full text in Research Archive
• Sævarang, Brage; Titelman, Josefin & Andersen, Tom (2022). Kvantifisering av hoppekrepsparasitter med digitale fluorescens-bilder. Universitetet i Oslo. Full text in Research Archive Show summary

  Hensikten med dette prosjektet var å utvikle en automatisert metode for å finne parasitter i hoppekreps. Jeg lette mer spesifikt etter Blastodinium som er en slekt av parasittiske dinoflagellater. Derfor ble det brukt propidiumjodid (PI), som er et stoff som fester seg på DNA. PI fluoriserer når det er bundet til DNA. Fordi dinoflagellatene har mer kompakt DNA lyste de mye sterkere enn hoppekrepsens kroppsvev. Det ble brukt en robot til å ta bilde av hele zooplanktonprøver, ikke bare enkeltdyr. Prøvene ble deretter analysert i bildebehandlingsprogrammet ImageJ med ZooProcess funksjonen. Denne funksjonen lager et eget bilde av hvert individ som var til stede i bildet. Det var flere av prøvene som viste tegn til parasitter. Metoden ble brukt på zooplankton-prøver fra et år i Oslofjorden. Tidsserien i Oslofjorden viste topper i parasittprevalens på over 10% i juni og juli. Parasittprevalensen for resten av året så ut til å holde seg rundt 5%. Det ble derfor vist at digitale fluorescens-bilder kan bli brukt til kvantifisering av hoppekrepsparasitter.

• Fransson, Agneta; Bluhm, Bodil; Arumi, Marti A.; Assmann, Karen; Gravelle, Amalie M. & Bratrein, Marius [Show all 34 contributors for this article] (2022). The Nansen Legacy Report Series. No. 30 - Joint Cruise 2-2 2021: Cruise report. UiT Norges arktiske universitet. Full text in Research Archive
• Assmy, Philipp; Gradinger, Rolf Rudolf; Edvardsen, Bente; Wold, Anette; Goraguer, Lucie Hélène Marie & Wiktor, Józef [Show all 8 contributors for this article] (2022). Phytoplankton biodiversity Nansen Legacy Q3. Norwegian Polar Institute. Full text in Research Archive

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