Jan David Heuschele

• 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. Fulltekst i vitenarkiv Vis sammendrag

  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.

• 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, s. 1026–1038. doi: 10.1007/s10646-024-02796-2. Fulltekst i vitenarkiv Vis sammendrag

  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.

• Albini, Dania; Lutier, Mathieu; Heimböck, Martin Paul; Heuschele, Jan David; Søreide, Janne & Jackson, Michelle C. [Vis alle 7 forfattere av denne artikkelen] (2024). Temporal patterns in multiple stressors shape the vulnerability of overwintering Arctic zooplankton. Ecology and Evolution. 14(7). doi: 10.1002/ece3.11673. Fulltekst i vitenarkiv Vis sammendrag

  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.

• 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. Fulltekst i vitenarkiv Vis sammendrag

  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.

• 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), s. 64–73. doi: 10.1111/fwb.14193. Fulltekst i vitenarkiv Vis sammendrag

  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

• Parra, Nicolas Valiente; Eiler, Alexander; Allesson, Lina; Andersen, Tom; Clayer, Francois & Crapart, Camille Marie [Vis alle 13 forfattere av denne artikkelen] (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. Fulltekst i vitenarkiv Vis sammendrag

  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.

• Heuschele, Jan David; Lode, Torben; Konestabo, Heidi Sjursen; Titelman, Josefin; Andersen, Tom & Borgå, Katrine (2022). Drivers of copper sensitivity in copepods: A meta-analysis of LC50s. Ecotoxicology and Environmental Safety. ISSN 0147-6513. 242. doi: 10.1016/j.ecoenv.2022.113907. Fulltekst i vitenarkiv Vis sammendrag

  Copper is both an essential trace element and a potent pesticide. The use of copper as an antifoulant has increased in the last decades in line with the expanding aquaculture and shipping industries. In aquatic environments, it also affects non-target taxa. One of which are copepods, which constitute the central link in the marine food web. Despite their ecological importance, there are no systematic reviews of the lethal concentration range and drivers of copper toxicity in this taxon. Here, we combined literature data from 31 peer-reviewed articles recording the Lethal Concentration 50 (LC50) for copper in copepods and the experiments' respective environmental, developmental, and taxonomic parameters. The LC50 is a traditional endpoint for toxicity testing used in standardized toxicity testing and many ecological studies. In total, we were able to extract 166 LC50 entries. The variability in the metadata allowed for a general analysis of the drivers of copper sensitivity in copepods. Using a generalized additive modeling approach, we find that temperature increases copper toxicity when above approximately 25 ℃. Counter to our expectations; salinity does not influence copper sensitivity across copepod species. Unsurprisingly, nauplii are more susceptible to copper exposure than adult copepods, and benthos-associated harpacticoids are less sensitive to copper than pelagic calanoids. Our final model can predict sensible specific-specific copper concentrations for future experiments, thus giving an informed analytical approach to range testing in future dose-response experiments. Our model can also potentially improve ecological risk assessment by accounting for environmental differences. The approach can be applied to other toxicants and taxa, which may reveal underlying patterns otherwise obscured by taxonomic and experimental variability.

• Kaartvedt, Stein; Ugland, Karl I.; Heuschele, Jan David & Solberg, Ingrid (2021). Coordinated gas release among the physostomous fish sprat (Sprattus sprattus). Scientific Reports. 11(1). doi: 10.1038/s41598-021-92585-2. Fulltekst i vitenarkiv Vis sammendrag

  Previous experimental studies suggest that the production of sound associated with expelling gas from an open swimbladder may play a role in communication. This would suggest non-random gas release. We used deployed echosounders to study patterns of gas release among a ford population of sprat (Sprattus sprattus). The echosounder records concurrently revealed individual fsh and their release of gas. The gas release primarily occurred at night, partly following recurrent temporal patterns, but also varying between nights. In testing for non-randomness, we formulated a datadriven simulation approach. Non-random gas release scaled with the length of the analyzed time intervals from 1 min to 6 h, and above 30 min the release events in more than 50% of the intervals were signifcantly connected.

• Lode, Torben; Heuschele, Jan David; Andersen, Tom; Titelman, Josefin; Hylland, Ketil & Borgå, Katrine (2021). Density-Dependent Metabolic Costs of Copper Exposure in a Coastal Copepod. Environmental Toxicology and Chemistry. ISSN 0730-7268. 40(9), s. 2538–2546. doi: 10.1002/etc.5141. Fulltekst i vitenarkiv Vis sammendrag

  Traditional ecotoxicology methods involving copepods have focused on exposure of pooled individuals and averaged responses, but there is increasing awareness of the importance of individual variation. Many biological traits are density dependent, and decisions to use single-individual or pooled exposure may affect responses to anthropogenic stressors. We investigated how conspecific density as a biotic stressor affects behavioral and respiratory responses to copper (Cu) exposure in the coastal copepod Tigriopus brevicornis. Adults were incubated at densities of 1, 2, or 4 individuals per replicate in 3.2 mL of exposure medium (23 µg Cu L–1 or control). Our results show an interaction of Cu exposure and density on respiration. The Cu exposure increased respiration, but this effect diminished with increasing density. We also found reduced swimming activity with increasing density. We propose 2 nonexclusive alternative explanations for the density-dependent respiratory increase of Cu exposure: 1) a behavioral stress response to low conspecific density, or 2) increased Cu exposure due to increased swimming activity. We emphasize the importance of considering density-dependency in responses when designing and interpreting ecotoxicology studies.

• Trapp, Aubrey; Heuschele, Jan David & Selander, Erik (2021). Eavesdropping on plankton—can zooplankton monitoring improve forecasting of biotoxins from harmful algae blooms? Limnology and Oceanography. ISSN 0024-3590. 66(9), s. 3455–3471. doi: 10.1002/lno.11891. Fulltekst i vitenarkiv Vis sammendrag

  Harmful algae bloom (HAB) forecasting has developed rapidly over recent decades, but predicting harmful levels of marine biotoxins in shellfish is still a challenge. New discoveries suggest that predator-prey interactions may be an important driver in the formation of HABs. Key species of harmful algae respond to copepod infochemicals with increased toxin production. In addition, copepods feed selectively on less defended prey, which may further promote harmful taxa. Here we explore if eavesdropping on predator-prey dynamics by monitoring zooplankton can improve HAB forecasting. We first examine an 8-yr time series including copepod biomass, harmful algae cells (Dinophysis spp.), and diarrhetic shellfish toxins in blue mussels (Mytilus edulis) using generalized additive models. Models including copepod biomass more accurately predicted okadaic acid in mussels than phytoplankton alone. We then apply this connection more narrowly by analyzing the specific copepod exudates known to induce toxin production, copepodamides, from the mussels sampled in biotoxin monitoring. Adding copepodamide data from shellfish extracts increased model performance compared to copepod biomass. Results suggest that including grazing effects through copepodamide measurements may provide a cost-efficient way to improve accuracy and lead time for predicting the accumulation of microalgal toxins in shellfish.

• Jager, Tjalling; Heuschele, Jan David; Lode, Torben & Borgå, Katrine (2021). Analysing individual growth curves for the copepod Tigriopus brevicornis, while considering changes in shape. Journal of Sea Research. ISSN 1385-1101. 174(102075). doi: 10.1016/j.seares.2021.102075. Fulltekst i vitenarkiv Vis sammendrag

  Understanding growth and development over ontogeny, and the effects of stressors on life history, requires bioenergetic analysis, for example using models based on dynamic energy budget theory. Such analyses require precise and accurate determination of the animal's biomass or biovolume over time. Automated imaging offers great advantages by allowing size measurements at a high temporal resolution and the possibility to follow individual animals, thus providing detailed growth trajectories as well as handles on inter-individual variation in growth. Here we report on a re-analysis of images from a life-cycle experiment with the coastal harpacticoid copepod Tigriopus brevicornis. Biovolume was estimated by approximating the organism's shape by a generalised ellipsoid. This analysis confirmed, rather unsurprisingly, that the moult from the last naupliar to the first copepodite stage is accompanied by a major change in shape. However, within the naupliar and copepodite stages, more gradual elongation was observed. These changes in shape imply that total body length is a poor proxy for body size throughout the developmental stages, and is therefore not suitable for bioenergetic analysis. Volumetric length (cubic root of estimated body volume) is far more appropriate. Interestingly, growth ceases for some 1.5 days around the moult to the first copepodite stage. Such a growth stop was not observed in earlier studies of several other copepod species. Furthermore, the growth rate of the copepodites exceeded that of the nauplii. These complexities in the life history of T. brevicornis pose challenges for bioenergetic analysis that will require determination of additional traits (e.g., feeding and respiration rates) to unravel.

• Lode, Torben; Heuschele, Jan David; Andersen, Tom; Titelman, Josefin; Hylland, Ketil & Borgå, Katrine (2020). Contrasting Effects of Predation Risk and Copper on Copepod Respiration Rates. Environmental Toxicology and Chemistry. ISSN 0730-7268. 39(9), s. 1765–1773. doi: 10.1002/etc.4804. Fulltekst i vitenarkiv Vis sammendrag

  Natural biotic and anthropogenic stressors can interact to alter contaminant toxicity. Energetic restrictions are potential mechanisms causing this pattern. To identify processes underlying observed effects of predation risk and copper (Cu) on delayed copepod age at maturity, we examined how these 2 stressors affect respiration rates. We tested 2 very different copepod species: the large, pelagic calanoid Calanus finmarchicus and the small, semibenthic harpacticoid Tigriopus brevicornis. Adult individuals were exposed for 12 h to the treatments: predation risk, Cu (23 µg L−1), combined predation risk and Cu (23 µg L−1), or control. Oxygen concentrations were monitored continuously. The 2 species differed in their responses. We found no clear effects of either stressor in C. finmarchicus. In T. brevicornis, predation risk increased respiration rates, whereas Cu alone had little impact. In contrast, combined exposure to predation risk and Cu interacted to reduce respiration rates to less than expected. We further observed an effect of sex because female‐biased T. brevicornis replicates were more sensitive to both predation risk (increased respiration rates) and Cu exposure (reduced respiration rates). The present study provides further evidence that predation risk can interact with copepod responses toward Cu exposure. Interactive effects of biotic stressors ought to be considered to improve future marine environmental monitoring. Environ Toxicol Chem 2020;39:1765–1773. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

• Heuschele, Jan David; Lode, Torben; Andersen, Tom & Titelman, Josefin (2020). The Hidden Dimension: Context‐Dependent Expression of Repeatable Behavior in Copepods. Environmental Toxicology and Chemistry. ISSN 0730-7268. 39(5), s. 1017–1026. doi: 10.1002/etc.4688. Fulltekst i vitenarkiv Vis sammendrag

  In ecotoxicology and aquatic ecology, we often ignore responses of individuals and focus on average responses. However, both terrestrial and aquatic animals display consistent behavioral differences between individuals. The distribution of behavioral differences within a population contains vital information for predicting population responses to novel environmental challenges. Currently, individual data for behavioral and physiological traits of small marine invertebrates are few, partly because such variation is lost within published group means and assumed normality. We tested the combined effects of an inorganic contaminant (copper) and a biological stressor (i.e., chemical cues of a fish predator) on activity in a marine copepod. Although direct stress effects were weak, individuals behaved consistently differently, depending on the context. Individual differences in behavior were only expressed under the influence of kairomones, but not by copper exposure alone. This finding indicates that copepods express repeatable and context‐dependent behavior. We also demonstrate how large variations in behavioral data can hide consistent differences between individuals. Environ Toxicol Chem 2020;39:1017–1026. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

• Sahlmann, Andrea Silke; Lode, Torben; Heuschele, Jan David; Borgå, Katrine; Titelman, Josefin & Hylland, Ketil (2019). Genotoxic Response and Mortality in 3 Marine Copepods Exposed to Waterborne Copper. Environmental Toxicology and Chemistry. ISSN 0730-7268. 38(10), s. 2224–2232. doi: 10.1002/etc.4541. Fulltekst i vitenarkiv
• Heuschele, Jan David; Lode, Torben; Andersen, Tom; Borgå, Katrine & Titelman, Josefin (2019). An affordable and automated imaging approach to acquire highly resolved individual data—an example of copepod growth in response to multiple stressors. PeerJ. 7, s. 1–22. doi: 10.7717/peerj.6776. Fulltekst i vitenarkiv Vis sammendrag

  Individual trait variation is essential for populations to cope with multiple stressors and continuously changing environments. The immense number of possible stressor combinations and the influence of phenotypic variation makes experimental testing for effects on organisms challenging. The acquisition of such data requires many replicates and is notoriously laborious. It is further complicated when responses occur over short time periods. To overcome such challenges, we developed an automated imaging platform to acquire temporally highly resolved individual data. We tested this platform by exposing copepods to a combination of a biotic stressor (predator cues) and a toxicant (copper) and measured the growth response of individual copepods. We tested the automatically acquired data against published manually acquired data with much lower temporal resolution. We find the same general potentiating effects of predator cues on the adverse effects of copper, and the influence of an individual’s clutch identity on its ability to resist stress, between the data obtained from low and high temporal resolution. However, when using the high temporal resolution, we also uncovered effects of clutch ID on the timing and duration of stage transitions, which highlights the importance of considering phenotypic variation in ecotoxicological testing. Phenotypic variation is usually not acknowledged in ecotoxicological testing. Our approach is scalable, affordable, and adjustable to accommodate both aquatic and terrestrial organisms, and a wide range of visually detectable endpoints. We discuss future extensions that would further widen its applicability.

• Wolf, Raoul & Heuschele, Jan David (2018). Water Browning Influences the Behavioral Effects of Ultraviolet Radiation on Zooplankton. Frontiers in Ecology and Evolution. 6, s. 1–8. doi: 10.3389/fevo.2018.00026. Fulltekst i vitenarkiv Vis sammendrag

  In the last decades, limnic water bodies in the Northern hemisphere have experienced a noticeable browning, i.e., increasing levels of dissolved organic matter (DOM). While the effects on primary producers is usually considered negative (light attenuation), zooplankton is thought to benefit from increased DOM, which absorbs harmful ultraviolet radiation (UVR). However, behavioral alterations due to browning in zooplankton have not yet been studied. We investigated the effects of a DOM gradient, alone and in combination with UVR, on the swimming behavior of Daphnia magna. Making use of a computer-controlled imaging system, we repeatedly filmed individuals over 6 h and analyzed the video material to unravel effects on exploration behavior and other motility patterns. The results show that increasing DOM buffers the detrimental effects of UVR on swimming behavior. This is likely due to attenuation of UVR by DOM. Interestingly, DOM also raised the overall swimming activity independent of UVR exposure. Our findings highlight the importance of DOM in freshwater systems, not only because of its physico-chemical properties, but also due to its higher-level effects on zooplankton communities.

• Lode, Torben; Heuschele, Jan David; Andersen, Tom; Titelman, Josefin; Hylland, Ketil & Borgå, Katrine (2018). Predation Risk Potentiates Toxicity of a Common Metal Contaminant in a Coastal Copepod. Environmental Science and Technology. ISSN 0013-936X. 52(22), s. 13535–13542. doi: 10.1021/acs.est.8b03685. Fulltekst i vitenarkiv
• Heuschele, Jan David; Ekvall, Mikael T.; Bianco, Giuseppe; Hylander, Samuel & Hansson, Lars-Anders (2017). Context-dependent individual behavioral consistency in Daphnia. Ecosphere. 8:e01679(2), s. 1–9. doi: 10.1002/ecs2.1679. Fulltekst i vitenarkiv
• Heuschele, Jan David; Ekvall, Mikael T.; Mariani, Patrizio & Lindemann, Christian (2017). On the missing link in ecology: improving communication between modellers and experimentalists. Oikos. ISSN 0030-1299. 126(8), s. 1071–1077. doi: 10.1111/oik.03885. Fulltekst i vitenarkiv
• Selander, Erik; Heuschele, Jan David & Larsson, Ann I. (2017). Hydrodynamic properties and distribution of bait downstream of a zooplankton trap. Journal of Plankton Research. ISSN 0142-7873. 39(6), s. 1020–1027. doi: 10.1093/plankt/fbx024. Fulltekst i vitenarkiv
• Selander, Erik; Heuschele, Jan David; Nylund, Göran M.; Pohnert, Georg; Pavia, Henrik & Bjærke, Oda [Vis alle 9 forfattere av denne artikkelen] (2016). Solid phase extraction and metabolic profiling of exudates from living copepods. PeerJ. 2016(1), s. 1–18. doi: 10.7717/peerj.1529. Fulltekst i vitenarkiv
• Heuschele, Jan David; Nemming, Louise; Tolstrup, Lea; Kiørboe, Thomas; Nylund, Göran M. & Selander, Erik (2016). The sex specific metabolic footprint of Oithona davisae. Journal of Sea Research. ISSN 1385-1101. 117, s. 1–6. doi: 10.1016/j.seares.2016.09.004. Fulltekst i vitenarkiv
• Heuschele, Jan David; Ceballos, Sara; Borg, Christian Marc Andersen; Bjærke, Oda; Isari, Stamatina & Lasley-Rasher, Rachel [Vis alle 10 forfattere av denne artikkelen] (2014). Non-consumptive effects of predator presence on copepod reproduction: insights from a mesocosm experiment. Marine Biology. ISSN 0025-3162. 161(7), s. 1653–1666. doi: 10.1007/s00227-014-2449-z. Fulltekst i vitenarkiv
• Sainmont, Julie; Gislason, Astthor; Heuschele, Jan David; Webster, Clare N.; Sylvander, Peter & Wang, Miao [Vis alle 7 forfattere av denne artikkelen] (2014). Inter- and intra-specific diurnal habitat selection of zooplankton during the spring bloom observed by Video Plankton Recorder. Marine Biology. ISSN 0025-3162. 161, s. 1931–1941. doi: 10.1007/s00227-014-2475-x. Fulltekst i vitenarkiv
• Heuschele, Jan David; Eliassen, Sigrunn & Kiørboe, Thomas (2013). Optimal mate choice patterns in pelagic copepods. Oecologia. ISSN 0029-8549. 172(2), s. 399–408. doi: 10.1007/s00442-012-2516-4. Fulltekst i vitenarkiv
• Heuschele, Jan David & Kiørboe, Thomas (2012). The smell of virgins: mating status of females affects male swimming behaviour in Oithona davisae. Journal of Plankton Research. ISSN 0142-7873. 34(11), s. 929–935. doi: 10.1093/plankt/fbs054. Fulltekst i vitenarkiv
• Heuschele, Jan David; Salminen, Tiina & Candolin, Ulrika (2012). Habitat change influences mate search behaviour in three-spined sticklebacks. Animal Behaviour. ISSN 0003-3472. 83(6), s. 1505–1510. doi: 10.1016/j.anbehav.2012.03.027. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Heuschele, Jan David (2026). Combining citizen science with assisted image classification to determine taxa composition in Norwegian seaweeds. Fulltekst i vitenarkiv
• Heuschele, Jan David & Johannessen, Ida (2026). Forskning på livet i havet - webinar 3. Fulltekst i vitenarkiv
• Johannessen, Ida & Heuschele, Jan David (2026). Folkeforskning - Forskning på livet i havet. Fulltekst i vitenarkiv
• Heuschele, Jan David & Garvang, Even Sletteng (2026). Hopp Hopp Hoppekreps - A Norwegian children's song about copepods. doi: 10.5281/ZENODO.22082053. Fulltekst i vitenarkiv Vis sammendrag

  "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.

• Supraha, Luka; Heuschele, Jan David & Leu, Eva (2026). From Ice to Open Water: Response of Arctic Mircoalgae to Changing Environmental Drivers. Fulltekst i vitenarkiv
• Heuschele, Jan David & Johannessen, Ida (2026). Forskning på livet i havet - Webinar 2. Fulltekst i vitenarkiv
• Nyeggen, Margot Ulfsdatter; Christiansen, Svenja; Garvang, Even Sletteng; Andersen, Tom; Heuschele, Jan David & Titelman, Josefin (2025). Zooplankton community dynamics in Oslofjorden. Fulltekst i vitenarkiv
• 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. Fulltekst i vitenarkiv Vis sammendrag

  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.

• Heuschele, Jan David & Johannessen, Ida (2025). Forskning på livet i havet - webinar 1. Fulltekst i vitenarkiv
• Heuschele, Jan David; Markova, Yana; Striebel, Maren; Andersen, Tom & Titelman, Josefin (2025). Uferflucht - Shore avoidance and other zooplankton dynamics in a coastal ecosystem. Fulltekst i vitenarkiv
• Heuschele, Jan David (2025). Uferflucht in a dynamic coastal habitat, or from POICE to MACROCOP. Fulltekst i vitenarkiv
• 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. Fulltekst i vitenarkiv
• Heuschele, Jan David (2025). Plankton i Oslofjorden. Fulltekst i vitenarkiv
• Heuschele, Jan David (2025). Introduction to the MACROCOP project - The hidden role of copepods in coastal macroalgae for marine ecosystem functioning. Fulltekst i vitenarkiv
• 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. Fulltekst i vitenarkiv
• Albini, Dania; Lutier, Mathieu; Heimböck, Martin Paul; Heuschele, Jan David; Søreide, Janne & Jackson, Michelle C [Vis alle 7 forfattere av denne artikkelen] (2024). Temporal patterns in multiple stressors shape the vulnerability of overwintering Arctic zooplankton. Fulltekst i vitenarkiv
• Borgå, Katrine; McKinney, Melissa A.; Giebichenstein, Julia; Dinh, van Khuong; Gravelle, Amalie Marie Bårnås & Heuschele, Jan David [Vis alle 10 forfattere av denne artikkelen] (2023). The influence of climate change on accumulation and toxicity of pollutants in Arctic marine food webs. Fulltekst i vitenarkiv
• Heuschele, Jan David; Lode, Torben; Bruserud, Hilde; Brochmann, Solveig; Dingstad, Trym Røil & Wolf, Raoul [Vis alle 7 forfattere av denne artikkelen] (2023). The population development of splash pool organisms under copper and predation risk exposure in field conditions. Fulltekst i vitenarkiv
• Heuschele, Jan David; Lode, Torben; Bruserud, Hilde; Brochmann, Solveig; Dingstad, Trym R & Wolf, Raoul [Vis alle 7 forfattere av denne artikkelen] (2023). Development of splash pool populations under copper and predation risk exposure in field conditions. Fulltekst i vitenarkiv
• Heuschele, Jan David; Dinh, Khuong V.; Lode, Torben; Jager, Tjalling & Borgå, Katrine (2022). Copper sensitivity in three common Arctic copepods. Fulltekst i vitenarkiv
• Lode, Torben; Dingstad, Trym R; Heuschele, Jan David & Borgå, Katrine (2022). Effect of historic aquaculture activity on copepod sensitivity to combined copper and predation risk exposure. Fulltekst i vitenarkiv
• Wolf, Raoul; Heuschele, Jan David; Wagner, Martin & Tollefsen, Knut-Erik (2019). Promoting data literacy to improve statistics in ecotoxicology. Fulltekst i vitenarkiv
• Lindemann, Christian & Heuschele, Jan David (2018). From peers to public: Obstacles, benefits and impact of cross-methodological communication. Fulltekst i vitenarkiv
• Vindenes, Yngvild; Broch, Catharina & Heuschele, Jan David (2018). Når oppveksten styres av temperatur - bidrag til Forskningstorget 2018. Fulltekst i vitenarkiv Vis sammendrag

  For de aller fleste dyr på jorda, er lengden på barndommen ikke et spørsmål om alder alene, men om hvor kaldt eller varmt miljøet i oppveksten har vært. For 99% av alle dyr på jorda er det temperaturen som bestemmer hvor raskt livsklokken tikker. Blant disse dyrene finner vi dafnier (vannlopper) som lever i små og store dammer der temperaturen kan skifte raskt og mye. Kom til vår bod og regn ut din egen dafnie-alder, hils på kalde og varme dafnier, og lær mer om hvordan temperatur påvirker lengden på barndommen og levealderen til disse dyrene.

• 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. Fulltekst i vitenarkiv
• 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. Fulltekst i vitenarkiv Vis sammendrag

  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.

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