kmagnus

Invited Review

2009 Norderhaug KM, Christie H. Sea urchin grazing and kelp re-vegetation in the NE Atlantic. Mar Biol Res 5:515-528.

Selected publications Peer Review Journals

2012 Norderhaug KM, Christie H, Andersen GS, Bekkby T. Does the diversity of kelp forest fauna increase with wave exposure? J Sea Res 69:36-42.

2011 Norderhaug KM, Christie H. Kelp forest secondary production and variation according to wave exposure. Est Coast Shelf Sci 95:135-144.

2007 Norderhaug KM, Christie H, Fredriksen S. Is habitat size an important factor for faunal abundances on kelp (Laminaria hyperborea)? J Sea Res. 58:120-124.

2006 Norderhaug KM, Nygaard K, Fredriksen S. Importance of phlorotannin content and C:N ratio of Laminaria hyberborea in determining its palatability as food for consumers. Mar Biol Res 2: 367-371

2005 Norderhaug KM, Christie H, Fosså JH, Fredriksen S. Fish-macrofauna interactions in a kelp (Laminaria hyperborea) forest. J Mar Biol Ass UK. 85:1279-1286.

2004 Norderhaug KM. Use of red algae as hosts by kelp-associated amphipods. Mar Biol, 144:225-230.

2003 Norderhaug KM, Fredriksen S, Nygaard K. The trophic importance of Laminaria hyperborea to kelp forest consumers and the importance of bacterial degradation for food quality. Mar Ecol Prog Ser 255: 135-144

2002 Norderhaug KM, Christie H, Rinde E. Colonisation of kelp imitations by epiphyte and holdfast fauna; a study of mobility patterns. Mar Biol 141:965-973

• Wernberg, Thomas; Filbee-Dexter, Karen; Bettignies, Thibaut de; Leclerc, Jean Charles; Davoult, Dominique & Lévêque, Laurent [Show all 13 contributors for this article] (2025). Smaller plants in warmer water could have implications for future Kelp forests. Scientific Reports. 15. doi: 10.1038/s41598-025-13950-z. Full text in Research Archive Show summary

  Global warming is driving contraction of species’ ranges through migration and mortality at their warm edge. However, for most species more subtle, sub-lethal changes in performance will be a more ubiquitous response to the Anthropocene. It has been suggested that reduction in body size will be a universal response to warming for cold-water species. Here we tested this hypothesis for two dominant kelp species in the northern and southern hemispheres, respectively. We tested if populations from cool and warm environments would be morphologically distinct, with warm-water populations displaying structural features indicative of sub-optimal conditions (smaller sizes). We found empirical evidence consistent with size reduction of kelp stipes, blades, and biomass of associated epiphytes from cool to warm water in both hemispheres. These changes are ecologically significant because they affect how kelps engineer their local environment, the three-dimensional habitat they create, and the associated communities they support. Reduced size of cold-water habitat forming species such as kelps may be a sublethal effect of warming that could have widespread but previously overlooked effects on the structure of ecosystems and the services that they provide.

• Norderhaug, Kjell Magnus; Kleiven, Portia Joy Nillos; Wernberg, Thomas; Synnes, Ann-Elin; Filbee-Dexter, Karen & Espeland, Sigurd Heiberg [Show all 10 contributors for this article] (2025). More but Smaller: Marine Heatwaves Exacerbate Size Truncation in Overfished Fish Communities in the Skagerrak. Ecology and Evolution. 15(5). doi: 10.1002/ece3.71404. Full text in Research Archive Show summary

  As we are progressing through the Anthropocene, it is imperative to understand how ecosystems degraded by historical impacts respond to future pressures. Particular attention should be directed at changes in the distribution and function of foundation species due to their disproportionately important ecological roles. Forest-forming kelps are in decline and are being replaced by turf-forming algae in coastal areas globally, as a consequence of increasingly severe marine heatwaves (MHW). This replacement represents a miniaturization of the three-dimensional habitat and a change in habitat functions for many associated species. Ecologically, economically, and culturally important coastal fish species depend on kelp forests in different life stages from egg to adult and may be affected in various ways. Many of these species already suffer from centuries of overexploitation, severely reducing abundances, truncating sizes, and changing age distributions. Here, we studied an overfished coastal ecosystem and assessed the impact of the transition from kelp to turf on the structure and function of associated fish communities. Specifically, we analyzed differences in abundance, body size, and composition of benthic fish at sites with variable cover of kelp and turf. We found higher abundances of small fish with increasing cover of turf relative to kelp. We also found smaller fish within the common families of gobids and gadids. Thus, MHW exacerbate size truncation and trophic downgrading in coastal fish communities. However, no differences in abundances of fish in the water column were detected during the night, and the average size of fish at turf-dominated sites was even larger. We interpreted this as roving predatory fish during night-time being less affected by the shift in habitat and smaller-bodied prey avoiding the water column in open turf habitats.

• Piñeiro-Corbeira, Cristina; Zimmerhackel, Johanna; Barreiro, Rodolfo; Bennett, Scott; Burton, Michael & Eger, Aaron M. [Show all 14 contributors for this article] (2025). The Habitat Dependency Index: A new tool for quantifying species-habitat relationships. Ecological Indicators. ISSN 1470-160X. 175, p. 1–9. doi: 10.1016/j.ecolind.2025.113612. Full text in Research Archive Show summary

  Habitat loss is a key threat to ecosystems and species that rely on them, with direct consequences for human well-being. Quantifying the degree to which species depend on specific habitats is critical for many fields of knowledge, such as conservation biology or economic valuations, yet poses a complex challenge. We introduce a new method to objectively quantify how much species depend on a habitat by integrating their life-cycle habitat associations. Through a comprehensive literature review focusing on 36 species associated with kelp forests, we demonstrate how this ‘Habitat Dependency Index’ (HDI) effectively discriminates between closely related species and captures differences in their reliance on kelp forests. We suggest this new HDI constitutes a powerful tool for understanding the role of marine habitats in supporting fisheries, biodiversity, and other ecosystem services. Moreover, the approach is broadly applicable and can provide essential information for managing both aquatic and terrestrial ecosystems.

• Bengtsson, Mia M. B.; Helgesen, Marita; Wang, Haitao; Fredriksen, Stein & Norderhaug, Kjell Magnus (2025). Sea urchin intestinal bacterial communities depend on seaweed diet and contain nitrogen-fixing symbionts. FEMS Microbiology Ecology. ISSN 0168-6496. 101(2), p. 1–10. doi: 10.1093/femsec/fiaf006. Full text in Research Archive Show summary

  Kelp deforestation by sea urchin grazing is a widespread phenomenon globally, with vast consequences for coastal ecosystems. The ability of sea urchins to survive on a kelp diet of poor nutritional quality is not well understood and bacterial communities in the sea urchin intestine may play an important role in digestion. A no-choice feeding experiment was conducted with the sea urchin Strongylocentrotus droebachiensis, offering three different seaweeds as diet, including the kelp Saccharina latissima. Starved sea urchins served as experimental control. Amplicons of the 16S rRNA gene were analyzed from fecal pellets. One dominant symbiont (Psychromonas marina) accounted for 44% of all sequence reads and was especially abundant in the sea urchins fed seaweed diets. The starved and field-captured sea urchins consistently displayed higher diversity than the seaweed-fed sea urchins. Cloning and sequencing of the nifH gene revealed diverse nitrogen fixers. We demonstrate that the sea urchin intestinal microbiome is dynamic, with bacterial communities that are plastic, depending on diet and have the capacity for nitrogen fixation. This reflects the dietary flexibility of these sea urchins, and their intestinal microbiota could be a key component in understanding catastrophic kelp forest grazing events.

• Filbee-Dexter, Karen; Starko, Samuel; Pessarrodona, Albert; Wood, Georgina; Norderhaug, Kjell Magnus & Piñeiro-Corbeira, Cristina [Show all 7 contributors for this article] (2024). Marine protected areas can be useful but are not a silver bullet for kelp conservation. Journal of Phycology. ISSN 0022-3646. 60(2), p. 203–213. doi: 10.1111/jpy.13446. Full text in Research Archive Show summary

  Kelp forests are among the most valuable ecosystems on Earth, but they are increasingly being degraded and lost due to a range of human-related stressors, leading to recent calls for their improved management and conservation. One of the primary tools to conserve marine species and biodiversity is the establishment of marine protected areas (MPAs). International commitments to protect 30% of the world's ecosystems are gaining momentum, offering a promising avenue to secure kelp forests into the Anthropocene. However, a clear understanding of the efficacy of MPAs for conserving kelp forests in a changing ocean is lacking. In this perspective, we question whether strengthened global protection will create meaningful conservation outcomes for kelp forests. We explore the benefits of MPAs for kelp conservation under a suite of different stressors, focusing on empirical evidence from protected kelp forests. We show that MPAs can be effective against some drivers of kelp loss (e.g., overgrazing, kelp harvesting), particularly when they are maintained in the long-term and enforced as no-take areas. There is also some evidence that MPAs can reduce impacts of climate change through building resilience in multi-stressor situations. However, MPAs also often fail to provide protection against ocean warming, marine heatwaves, coastal darkening, and pollution, which have emerged as dominant drivers of kelp forest loss globally. Although well-enforced MPAs should remain an important tool to protect kelp forests, successful kelp conservation will require implementing an additional suite of management solutions that target these accelerating threats.

• Norderhaug, Kjell Magnus; Knutsen, Halvor; Filbee-Dexter, Karen; Sodeland, Marte; Jorde, Per Erik & Wernberg, Thomas [Show all 8 contributors for this article] (2024). The International Union for Conservation of Nature Red List does not account for intraspecific diversity. ICES Journal of Marine Science. ISSN 1054-3139. 81(5), p. 815–822. doi: 10.1093/icesjms/fsae039. Full text in Research Archive Show summary

  The International Union for Conservation of Nature (IUCN) Red List identifies threatened and endangered species and is a key instrument in global biodiversity conservation efforts. Our understanding of the structure and value of genetic biodiversity below the species level is rapidly increasing. Nonetheless, the IUCN assessment criteria overlook genetic variation within species. Here, we address this blind spot and discuss the principles of species conservation status classification relative to intraspecific biodiversity. We focus on coastal species, which thrive in heterogeneous environments known to drive genetic differentiation. The focal example species, Atlantic cod and sugar kelp, have contrasting life histories, are ecologically and economically important constituents of the coastal ecosystem, and are currently not classified as threatened in Norway and Canada. We expose important variation in population structure, the presence of ecotypes and genetic-environment covariation, as well as loss of ecotypes that threatens the conservation of these species. Because the genetic makeup of species directly influences their resilience, omitting this information from conservation status assessments can result in loss of adaptive capacity to future stressors, such as climate change. Consequently, recognizing and preserving intraspecific variation emerges as vital for species’ abilities to adapt to and survive in future ocean conditions.

• Gagnon, Karine; Thormar, Jonas; Fredriksen, Stein; Potouroglou, Maria; Albretsen, Jon & Gundersen, Hege [Show all 10 contributors for this article] (2024). Carbon stocks in Norwegian eelgrass meadows across environmental gradients. Scientific Reports. 14. doi: 10.1038/s41598-024-74760-3. Full text in Research Archive Show summary

  Seagrass meadows are well-known for their capacity to capture and store blue carbon in sediments. However carbon stocks vary significantly between meadows, spanning more than three orders of magnitude on both local and global scales. Understanding the drivers of seagrass carbon stocks could help improve strategies for incorporating blue carbon into management plans. Here, we measured sediment carbon stocks in eelgrass (Zostera marina) meadows and unvegetated areas along the Norwegian coast, spanning wide gradients in temperature, wave exposure, water depth, salinity, and eelgrass biomass. Carbon stocks were generally higher in eelgrass meadows than in adjacent unvegetated areas, yet they displayed considerable variation (400 − 30 000 g C m−2 at 50 cm sediment depth) even among nearby sites. Overall, the highest carbon stocks were found in deeper, muddier, sheltered meadows near river mouths. These sites likely have the highest input and retention of carbon from different sources. Consequently, they should be prioritized as conservation targets for preserving coastal blue carbon stocks. Despite ever-increasing efforts to quantify seagrass blue carbon globally, high uncertainties still persist, partly due to differing methodologies, processes, and environmental context. Blue carbon stock estimates could be improved through the coordination of standardised mapping and sampling methods.

• Smale, Daniel; Thomsen, M; Bennett, S; Duarte, Carlos M.; Eger, Aron & Filbee-Dexter, Karen [Show all 22 contributors for this article] (2023). Biodiversity and ecosystem services. In Potouroglou, Maria; Filbee-Dexter, Karen; Lutz, Steven; Grimsditch, Gabriel; Jonsson, Linda & Gundersen, Hege (Ed.), Into the Blue: Securing a Sustainable Future for Kelp Forests. GRID-Arendal. ISSN 9789280740073. p. 45–70. Full text in Research Archive
• Kartveit, Kyrre Heldal; Filbee-Dexter, Karen; Steen, Henning; Christensen, Lene & Norderhaug, Kjell Magnus (2022). Efficient spatial kelp biomass estimations using acoustic methods. Frontiers in Marine Science. 9. doi: 10.3389/fmars.2022.1065914. Full text in Research Archive Show summary

  Kelp forests are the largest vegetated marine ecosystem on earth, but vast areas of their distribution remain unmapped and unmonitored. Efficient and cost-effective methods for measuring the standing biomass of these ecosystems are urgently needed for coastal mapping, ocean accounting and sustainable management of wild harvest. Here we show how widely available acoustic equipment on vessels can be used to perform robust and large-scale (kilometer) quantifications of kelp biomass which can be used in assessments and monitoring programs. We demonstrate how to interpret echograms from acoustic systems into point estimates of standing biomass in order to create spatial maps of biomass distribution. We also explore what environmental conditions are suitable for acoustic measures. This has direct application for blue carbon accounting, coastal monitoring, management of wild seaweed harvest and the protection and conservation of marine habitats supporting high biodiversity.

• Filbee-Dexter, Karen; Feehan, Colette J.; Smale, Dan A.; Krumhansl, Kira A.; Augustine, Skye & Bettignies, Florian de [Show all 26 contributors for this article] (2022). Kelp carbon sink potential decreases with warming due to accelerating decomposition. PLoS Biology. ISSN 1544-9173. 20(8). doi: 10.1371/journal.pbio.3001702. Full text in Research Archive Show summary

  Cycling of organic carbon in the ocean has the potential to mitigate or exacerbate global climate change, but major questions remain about the environmental controls on organic carbon flux in the coastal zone. Here, we used a field experiment distributed across 28° of latitude, and the entire range of 2 dominant kelp species in the northern hemisphere, to measure decomposition rates of kelp detritus on the seafloor in relation to local environmental factors. Detritus decomposition in both species were strongly related to ocean temperature and initial carbon content, with higher rates of biomass loss at lower latitudes with warmer temperatures. Our experiment showed slow overall decomposition and turnover of kelp detritus and modeling of coastal residence times at our study sites revealed that a significant portion of this production can remain intact long enough to reach deep marine sinks. The results suggest that decomposition of these kelp species could accelerate with ocean warming and that low-latitude kelp forests could experience the greatest increase in remineralization with a 9% to 42% reduced potential for transport to long-term ocean sinks under short-term (RCP4.5) and long-term (RCP8.5) warming scenarios. However, slow decomposition at high latitudes, where kelp abundance is predicted to expand, indicates potential for increasing kelp-carbon sinks in cooler (northern) regions. Our findings reveal an important latitudinal gradient in coastal ecosystem function that provides an improved capacity to predict the implications of ocean warming on carbon cycling. Broad-scale patterns in organic carbon decomposition revealed here can be used to identify hotspots of carbon sequestration potential and resolve relationships between carbon cycling processes and ocean climate at a global scale.

• Filbee-Dexter, Karen; Wernberg, Thomas; Barreiro, Rodolfo; Coleman, Melinda A.; Bettignies, Thibaut de & Feehan, Colette J. [Show all 13 contributors for this article] (2022). Leveraging the blue economy to transform marine forest restoration. Journal of Phycology. ISSN 0022-3646. 58(2), p. 198–207. doi: 10.1111/jpy.13239. Full text in Research Archive
• Bosch, Nestor E.; Wernberg, Thomas; Langlois, Tim J.; Smale, Dan A; Moore, Pippa J. & Franco, João N [Show all 19 contributors for this article] (2021). Niche and neutral assembly mechanisms contribute to latitudinal diversity gradients in reef fishes. Journal of Biogeography. ISSN 0305-0270. 48(11), p. 2683–2698. doi: 10.1111/jbi.14237. Full text in Research Archive
• Pessarrodona, Albert; Filbee-Dexter, Karen; Alcoverro, Teresa; Boada, Jordi; Feehan, Colette J. & Fredriksen, Stein [Show all 11 contributors for this article] (2021). Homogenization and miniaturization of habitat structure in temperate marine forests. Global Change Biology. ISSN 1354-1013. doi: 10.1111/gcb.15759. Full text in Research Archive Show summary

  Humans are rapidly transforming the structural configuration of the planet's ecosystems, but these changes and their ecological consequences remain poorly quantified in underwater habitats. Here, we show that the loss of forest-forming seaweeds and the rise of ground-covering ‘turfs’ across four continents consistently resulted in the miniaturization of underwater habitat structure, with seascapes converging towards flattened habitats with smaller habitable spaces. Globally, turf seascapes occupied a smaller architectural trait space and were structurally more similar across regions than marine forests, evidencing habitat homogenization. Surprisingly, such habitat convergence occurred despite turf seascapes consisting of vastly different species richness and with different taxa providing habitat architecture, as well as across disparate drivers of marine forest decline. Turf seascapes contained high sediment loads, with the miniaturization of habitat across 100s of km in mid-Western Australia resulting in reefs retaining an additional ~242 million tons of sediment (four orders of magnitude more than the sediments delivered fluvially annually). Together, this work demonstrates that the replacement of marine forests by turfs is a generalizable phenomenon that has profound consequences for the ecology of temperate reefs.

• Haugland, Barbro Taraldset; Armitage, Caroline S.; Kutti, Tina; Husa, Vivian; Skogen, Morten D. & Bekkby, Trine [Show all 11 contributors for this article] (2021). Large-scale salmon farming in Norway impacts the epiphytic community of Laminaria hyperborea. Aquaculture Environment Interactions. ISSN 1869-215X. 13, p. 81–100. doi: 10.3354/AEI00392. Full text in Research Archive Show summary

  Large-scale finfish farms are increasingly located in dispersive hard-bottom environments where Laminaria hyperborea forests dominate; however, the interactions between farm effluents and kelp forests are poorly understood. Effects of 2 levels of salmonid fish-farming effluents (high and low) on L. hyperborea epiphytic communities were studied by sampling canopy plants from 12 sites in 2 high-energy dispersive environments. Specifically, we assessed if farm effluents stimulated fast-growing epiphytic algae and faunal species on L. hyperborea stipes—as this can impact the kelp forest community composition—and/or an increased lamina epiphytic growth, which could negatively impact the kelp itself. We found that bryozoan biomass on the stipes was significantly higher at high-effluent farm sites compared to low-effluent farm and reference sites, resulting in a significantly different epiphytic community. Macroalgal biomass also increased with increasing effluent levels, including opportunistic Ectocarpus spp., resulting in a less heterogeneous macroalgae community at high-effluent farm sites. This habitat heterogeneity was further reduced by the high bryozoan biomass at the high-effluent sites. Such changes in the epiphyte community could have implications for the faunal community that relies on the epiphytes for food and refuge. On the kelp lamina, no clear response to farm effluents was found.

• Pedersen, Morten Foldager; Filbee-Dexter, Karen; Norderhaug, Kjell Magnus; Fredriksen, Stein; Frisk, Nicolai Lond & Fagerli, Camilla With [Show all 7 contributors for this article] (2020). Detrital carbon production and export in high latitude kelp forests. Oecologia. ISSN 0029-8549. 192(1), p. 227–239. doi: 10.1007/s00442-019-04573-z. Full text in Research Archive Show summary

  The production and fate of seaweed detritus is a major unknown in the global C-budget. Knowing the quantity of detritus produced, the form it takes (size) and its timing of delivery are key to understanding its role as a resource subsidy to secondary production and/or its potential contribution to C-sequestration. We quantified the production and release of detritus from 10 Laminaria hyperborea sites in northern Norway (69.6° N). Kelp biomass averaged 770 ± 100 g C m−2 while net production reached 499 ± 50 g C m−2 year−1, with most taking place in spring when new blades were formed. Production of biomass was balanced by a similar formation of detritus (478 ± 41 g C m−2 year−1), and both were unrelated to wave exposure when compared across sites. Distal blade erosion accounted for 23% of the total detritus production and was highest during autumn and winter, while dislodgment of whole individuals and/or whole blades corresponded to 24% of the detritus production. Detachment of old blades constituted the largest source of kelp detritus, accounting for > 50% of the total detrital production. Almost 80% of the detritus from L. hyperborea was thus in the form of whole plants or blades and > 60% of that was delivered as a large pulse within 1–2 months in spring. The discrete nature of the delivery suggests that the detritus cannot be retained and consumed locally and that some is exported to adjacent deep areas where it may subsidize secondary production or become buried into deep marine sediments as blue carbon.

• Fredriksen, Stein; Filbee-Dexter, Karen; Norderhaug, Kjell Magnus; Steen, Henning; Bodvin, Torjan & Coleman, Melinda A. [Show all 8 contributors for this article] (2020). Green gravel: a novel restoration tool to combat kelp forests decline. Scientific Reports. 10, p. 1–7. doi: 10.1038/s41598-020-60553-x. Full text in Research Archive Show summary

  Kelp forests are in decline globally and large-scale intervention could be required to halt the loss of these valuable ecosystems. To date kelp forest restoration has had limited success and been expensive and unable to address the increasing scale of ecosystem deterioration. Here we developed and tested a new approach: “green gravel”. Small rocks were seeded with kelp and reared in the laboratory until 2–3 cm, before out-planting to the field. The out-planted kelp had high survival and growth over 9 months, even when dropped from the surface. This technique is cheap, simple, and does not require scuba diving or highly trained field workers. It can be up-scaled to treat large areas or even used to introduce genes from more resilient kelp populations onto vulnerable reefs. Green gravel thus overcomes some of the current major limitations of kelp restoration and provides a promising new defense against kelp forest decline.

• Filbee-Dexter, Karen; Wernberg, Thomas; Grace, S.P.; Thormar, Jonas; Fredriksen, Stein & Narvaez, C.N. [Show all 8 contributors for this article] (2020). Marine heatwaves and the collaps of marginal North Atlantic kelp forests. Scientific Reports. 10. doi: 10.1038/s41598-020-70273-x. Full text in Research Archive Show summary

  Extreme climatic events including marine heatwaves (MHWs) are becoming more frequent and severe in the Anthropocene. However, our understanding of how these events affect population dynamics of ecologically important species is limited, in part because extreme events are rare and difficult to predict. Here, we quantified the occurrence and severity of MHWs over 60 years in warm range edge kelp forests on both sides of the North Atlantic. The cumulative annual intensity of MHWs increased two- to four-fold during this period, coinciding with the disappearance of kelps. We experimentally demonstrated a relationship between strong and severe 2018 heatwaves and high kelp mortality in both regions. Patterns of kelp mortality were strongly linked to maximum temperature anomalies, which crossed lethal thresholds in both regions. Translocation and tagging experiments revealed similar kelp mortality rates on reefs dominated by healthy kelp forests and degraded sediment-laden algal ‘turfs’, indicating equal vulnerability to extreme events. These results suggest a mechanistic link between MHWs and broad-scale kelp loss, and highlight how warming can make ecosystem boundaries unstable, forcing shifts to undesirable ecosystem states under episodically extreme climatic conditions.

• Filbee-Dexter, Karen; Pedersen, Morten Foldager; Fredriksen, Stein; Norderhaug, Kjell Magnus; Rinde, Eli & Kristiansen, Trond [Show all 8 contributors for this article] (2020). Carbon export is facilitated by sea urchins transforming kelp detritus. Oecologia. ISSN 0029-8549. 192, p. 213–225. doi: 10.1007/s00442-019-04571-1. Full text in Research Archive Show summary

  With the increasing imperative for societies to act to curb climate change by increasing carbon stores and sinks, it has become critical to understand how organic carbon is produced, released, transformed, transported, and sequestered within and across ecosystems. In freshwater and open-ocean systems, shredders play a significant and well-known role in transforming and mobilizing carbon, but their role in the carbon cycle of coastal ecosystems is largely unknown. Marine plants such as kelps produce vast amounts of detritus, which can be captured and consumed by shedders as it traverses the seafloor. We measured capture and consumption rates of kelp detritus by sea urchins across four sampling periods and over a range of kelp detritus production rates and sea urchin densities, in northern Norway. When sea urchin densities exceeded 4 m−2, the sea urchins captured and consumed a high percentage (ca. 80%) of kelp detritus on shallow reefs. We calculated that between 1.3 and 10.8 kg of kelp m−2 are shredded annually from these reefs. We used a hydrodynamic dispersal model to show that transformation of kelp blades to sea urchin feces increased its export distance fourfold. Our findings show that sea urchins can accelerate and extend the export of carbon to neighboring areas. This collector–shredder pathway could represent a significant flow of small particulate carbon from kelp forests to deep-sea areas, where it can subsidize benthic communities or contribute to the global carbon sink.

• Christensen-Dalsgaard, Signe; Mattisson, Jenny; Norderhaug, Kjell Magnus & Lorentsen, Svein Håkon (2020). Sharing the neighbourhood: assessing the impact of kelp harvest on foraging behaviour of the European shag. Marine Biology. ISSN 0025-3162. 167. doi: 10.1007/s00227-020-03739-1. Full text in Research Archive Show summary

  Coastal kelp forest ecosystems create dynamic and productive habitats, supporting a wide range of epiphytic flora, invertebrates, fish and seabirds. Worldwide, kelp is harvested commercially, affecting kelp-associated animal communities. There is, however, limited knowledge of how fish and seabird respond to kelp harvest, highlighting the need to evaluate the ecological impact of harvest on all ecosystem levels. Using 6 years of GPS-tracking data, we examined the effects of kelp harvest on foraging behaviour of breeding European shags (Phalacrocorax aristotelis) from a colony in central Norway. We determined the spatial overlap between kelp harvest and foraging areas of shags and assessed the immediate, short- and long-term impacts of harvest on shag foraging behaviour. Our results demonstrated large spatial and temporal overlap in areas used by foraging shags and kelp harvest. We could not detect any clear alterations in the diving activity of shags due to kelp harvest. However, the broad temporal and spatial scale of our study constrained the detection of fine scale changes in shag behaviour in response to kelp harvest. Our study, nonetheless, identifies several issues that should be addressed before concluding on the effects of kelp harvest on seabird populations. This includes the need for experimental studies using directed and controlled harvest to investigate the effects of kelp harvest through the different trophic levels, including top predators. This is essential for ecosystem-based management of coastal resources, considering the many species composed in the coastal ecosystem.

• Vilas, Daniel; Coll, Marta; Pedersen, Torstein; Corrales, Xavier; Filbee-Dexter, Karen & Pedersen, Morten Foldager [Show all 10 contributors for this article] (2020). Kelp-carbon uptake by Arctic deep-sea food webs plays a noticeable role in maintaining ecosystem structural and functional traits. Journal of Marine Systems. ISSN 0924-7963. 203. doi: 10.1016/j.jmarsys.2019.103268. Full text in Research Archive Show summary

  The flow of non-living carbon (detritus) is considered an important process because it connects ecosystems and fuels benthic communities. In Norwegian kelp forests, 90% of the kelp production is exported to adjacent ecosystems where it can play a significant role in shaping benthic communities. We quantified the major structural and functional traits of an Arctic deep-sea ecosystem associated with kelp exports and assessed the ecological role of kelp export into the deep-sea system. We first developed a food-web model using the Ecopath with Ecosim (EwE) approach to represent the state of the deep (450 m) ecosystem of the Malangen fjord (Northern Norway) in 2017. Subsequently, we used the temporal dynamic model Ecosim to explore the structure and functioning traits of a theoretical deep-sea ecosystem projecting a decrease of kelp detritus biomass reaching the deep-sea ecosystem. Overall, our findings reveal that kelp detritus from shallow coastal areas has a small but noticeable role structuring the deep-sea ecosystem of Malangen. The temporal simulations show important differences depending on the application of mediating effects, which allow considering the detritus as a mediating group in prey-predator interaction, in addition to its direct role in trophic relationships. When mediating effects are applied, biomass increases for benthopelagic shrimps and suprabenthos groups and decreases for rays and skates, velvet belly, rabbitfish and other commercial demersal fishes under the low kelp detritus scenarios. Biomass-based and trophic-based indicators reveal a noticeable impact on the deep-sea ecosystem structure due to depletion of kelp detritus. To further assess future changes of the Arctic deep-sea ecosystems, dependencies with adjacent ecosystems, such as kelp detritus production, should be included.

• Son, Thijs Christiaan van; Nikolioudakis, Nikolaos; Steen, Henning; Albretsen, Jon; Furevik, Birgitte Rugaard & Elvenes, Sigrid [Show all 8 contributors for this article] (2020). Achieving Reliable Estimates of the Spatial Distribution of Kelp Biomass. Frontiers in Marine Science. 7. doi: 10.3389/fmars.2020.00107. Full text in Research Archive Show summary

  Kelp forests are highly productive systems that are important ecologically and commercially as well as in a blue carbon perspective. Given their importance, there is an urgent need to achieve reliable estimates of the spatial distribution of their biomass. Species distribution modelling is a powerful tool for producing such estimates, but it requires a solid framework, including important environmental covariates that have a direct effect on their biomass, a proper sampling strategy, and an independent evaluation dataset. Using Laminaria hyperborea as a model species, we developed a modelling framework considering these requirements and necessary steps to produce reliable predictions. Our modelling framework included proportion of hard substrate and bottom wave exposure, both crucial covariates that have a direct effect on the biomass of L. hyperborea, but rarely included in modelling studies. Furthermore, we devised a sampling strategy with field observations covering the whole environmental covariate space present in the study area. Subsequently, we fitted GAMs relating the field observations of the biomass of L. hyperborea to relevant environmental covariates. The best model containing the predictors bottom wave exposure, depth, and proportion hard substrate explained most of the variance in the dataset (83.1% deviance explained). This model was then used to predict the spatial distribution of biomass across the whole study area. To assess the reliability of the biomass predictions, we used an independent dataset of L. hyperborea biomass observations from the same area. This independent dataset correlated very well with spatial predictions of biomass based on our best model (R = 0.85). In total, we predicted a biomass of 457,000 tonnes in a 1,150 km2 study area on the West coast of Norway. Our modelling framework provides the means for developing a biomass model on a broader geographical scale. Such a model will be invaluable in improving kelp management regimes as well as for estimating the contribution of kelp forests to ecosystem services such as carbon sequestration and climate budgets.

• Norderhaug, Kjell Magnus; Nedreaas, Kjell Harald; Huserbråten, Mats & Moland, Even (2020). Depletion of coastal predatory fish sub-stocks coincided with the largest sea urchin grazing event observed in the NE Atlantic. Ambio. ISSN 0044-7447. 50, p. 163–173. doi: 10.1007/s13280-020-01362-4. Full text in Research Archive Show summary

  In this contribution, we propose fishery driven predator release as the cause for the largest grazing event ever observed in the NE Atlantic. Based on the evolving appreciation of limits to population connectivity, published and previously unpublished data, we discuss whether overfishing caused a grazer bloom of the sea urchin (Strongylocentrotus droebachiensis) resulting in overgrazing of more than 2000 km2 kelp (Laminaria hyperborea) forest along Norwegian and Russian coasts during the 1970 s. We show that coastal fisheries likely depleted predatory coastal fish stocks through modernization of fishing methods and fleet. These fish were important predators on urchins and the reduction coincided with the urchin bloom. From this circumstantial evidence, we hypothesize that coastal predatory fish were important in regulating sea urchins, and that a local population dynamics perspective is necessary in management of coastal ecosystems.

• Norderhaug, KM; Filbee-Dexter, K; Freitas, Carla; Birkely, Sten Richard; Christensen, Lene & Mellerud, Ida Kristin [Show all 11 contributors for this article] (2020). Ecosystem-level effects of large-scale disturbance in kelp forests. Marine Ecology Progress Series. ISSN 0171-8630. 656, p. 163–180. doi: 10.3354/meps13426. Full text in Research Archive Show summary

  Understanding the effects of ecological disturbances in coastal habitats is crucial and timely as these are anticipated to increase in intensity and frequency in the future due to increasing human pressure. In this study we used directed kelp trawling as a scientific tool to quantify the impacts of broad-scale disturbance on community structure and function. We tested the ecosystem-wide effects of this disturbance in a BACI design using two 15 km 2 areas. The disturbance had a substantial impact on the kelp forests in this study, removing 2986 tons of kelp and causing a 26% loss of total kelp canopy at trawled stations. This loss created a 67% reduction of epiphytes, an 89% reduction of invertebrates and altered the fish populations living within these habitats. The effect of habitat loss on fish was variable and depended on how the different species used the habitat structure. Our results show that large-scale experimental disturbances on habitat-forming species have ecological consequences that extend beyond the decline of the single species to affect multiple trophic levels of the broader ecosystem. Our findings have relevance for understanding how increasing anthropogenic disturbances, including kelp trawling and increased storm frequency caused by climate change, may alter ecosystem structure and function.

• Christie, Hartvig; Gundersen, Hege; Rinde, Eli; Filbee-Dexter, Karen; Norderhaug, Kjell Magnus & Pedersen, Torstein [Show all 9 contributors for this article] (2019). Can multitrophic interactions and ocean warming influence large-scale kelp recovery? Ecology and Evolution. 9(5), p. 2847–2862. doi: 10.1002/ece3.4963. Full text in Research Archive Show summary

  Ongoing changes along the northeastern Atlantic coastline provide an opportunity to explore the influence of climate change and multitrophic interactions on the recovery of kelp. Here, vast areas of sea urchin‐dominated barren grounds have shifted back to kelp forests, in parallel with changes in sea temperature and predator abundances. We have compiled data from studies covering more than 1,500‐km coastline in northern Norway. The dataset has been used to identify regional patterns in kelp recovery and sea urchin recruitment, and to relate these to abiotic and biotic factors, including structurally complex substrates functioning as refuge for sea urchins. The study area covers a latitudinal gradient of temperature and different levels of predator pressure from the edible crab (Cancer pagurus) and the red king crab (Paralithodes camtschaticus). The population development of these two sea urchin predators and a possible predator on crabs, the coastal cod (Gadus morhua), were analyzed. In the southernmost and warmest region, kelp forests recovery and sea urchin recruitment are mainly low, although sea urchins might also be locally abundant. Further north, sea urchin barrens still dominate, and juvenile sea urchin densities are high. In the northernmost and cold region, kelp forests are recovering, despite high recruitment and densities of sea urchins. Here, sea urchins were found only in refuge habitats, whereas kelp recovery occurred mainly on open bedrock. The ocean warming, the increase in the abundance of edible crab in the south, and the increase in invasive red king crab in the north may explain the observed changes in kelp recovery and sea urchin distribution. The expansion of both crab species coincided with a population decline in the top‐predator coastal cod. The role of key species (sea urchins, kelp, cod, and crabs) and processes involved in structuring the community are hypothesized in a conceptual model, and the knowledge behind the suggested links and interactions is explored.

• Duffy, J. Emmett; Benedetti-Cecchi, Lisandro; Trinanes, Joaquin A.; Muller-Karger, Frank E.; Ambo-Rappe, Rohani & Boström, Christoffer [Show all 49 contributors for this article] (2019). Toward a coordinated global observing system for seagrasses and marine macroalgae. Frontiers in Marine Science. 6:317, p. 1–26. doi: 10.3389/fmars.2019.00317. Full text in Research Archive
• Christie, Hartvig; Bekkby, Trine; Norderhaug, Kjell Magnus; Beyer, Jonny & Jørgensen, Nina Mari (2019). Can sea urchin grazing of kelp forests in the Arctic make rocky shore systems more vulnerable to oil spills? Polar Biology. ISSN 0722-4060. 42(3), p. 557–567. doi: 10.1007/s00300-018-02450-8. Full text in Research Archive Show summary

  In Arctic Norway, the risk of major marine oil spills associated with increasing offshore drilling, land terminal, and maritime transport activities is a cause for concern. Intertidal and subtidal kelp and seaweed communities found in this region are highly productive ecosystems, although sea urchin (Strongylocentrotus droebachiensis)-overgrazed areas (urchin barrens) have been and still are a widespread problem. In the present study, we developed a kelp (Laminaria hyperborea) distribution model and studied fauna distribution, dispersal and recolonisation potentials in seaweed communities, kelp forests and sea urchin-grazed areas to assess sensitivity and vulnerability of these rocky shore communities to additional stress from oil spills, especially if the oil is released close to the coast. Our results suggest that sheltered and moderately exposed rocky shore seaweed communities close to urchin barrens are the most sensitive systems when a combined ecological effect from grazing and oil spill pollution is considered. Our study may have implications for which oil spill countermeasures that represent the best environmental practice (BEP) in the northern coastal areas that already are ecologically stressed because of sea urchin overgrazing.

• Filbee-Dexter, Karen; Wernberg, Thomas; Fredriksen, Stein; Norderhaug, Kjell Magnus & Pedersen, Morten Foldager (2019). Arctic kelp forests: Diversity, resilience and future. Global and Planetary Change. ISSN 0921-8181. 172, p. 1–14. doi: 10.1016/j.gloplacha.2018.09.005. Full text in Research Archive Show summary

  The Arctic is one of the most rapidly changing places on Earth and it is a sentinel region for understanding the range and magnitude of planetary changes, and their impacts on ecosystems. However, our understanding of arctic coastal ecosystems remains limited, and the impacts of ongoing and future climate change on them are largely unexplored. Kelp forests are the dominant habitat along many rocky Arctic coastlines, providing structure and food for economically and ecologically important species. Here we synthesize existing information on the distribution and diversity of arctic kelp forests and assess how ongoing changes in environmental conditions could impact the extent, productivity, and resilience of these important ecosystems. We identify regions where the range and growth of arctic kelp are likely to undergo rapid short-term increase due to reduced sea ice cover, increased light, and warming. However, we also describe areas where kelps could be negatively impacted by rising freshwater input and coastal erosion due to receding sea ice and melting permafrost. In some regions, arctic kelp forests have undergone sudden regime shifts due to altered ecological interactions or changing environmental conditions. Key knowledge gaps for arctic kelp forests include measures of extent and diversity of kelp communities (especially northern Canada and northeastern Russia), the faunal communities supported by many of these habitats, and the role of arctic kelp forests in structuring nearby pelagic and benthic food webs. Filling in these gaps and strategically prioritizing research in areas of rapid environmental change will enable more effective management of these important habitats, and better predictions of future changes in the coastal ecosystems they support and the services that they provide.

• Trannum, Hilde Cecilie; Gundersen, Hege; Oug, Eivind; Rygg, Brage & Norderhaug, Kjell Magnus (2018). Soft bottom benthos and responses to climate variation and eutrophication in Skagerrak. Journal of Sea Research. ISSN 1385-1101. 141, p. 83–98. doi: 10.1016/j.seares.2018.08.007. Full text in Research Archive Show summary

  Skagerrak has been subject to several anthropogenic influences over the past decades, with climate change and eutrophication being considered as the most serious and large-scale disturbance factors. The present study reports monitoring data from six soft bottom stations in 50–380 m depth at the Norwegian Skagerrak coast aimed at investigating to which degree changes in environmental conditions have affected species communities and diversity. Sampling was carried out yearly in the period 1990–2010. Links between benthic community patterns and climate factors and physicochemical variables from the water mases were examined using uni- and multivariate statistical methods. Throughout the period species richness gradually increased. Although all stations showed distinct species assemblages, the community composition gradually changed towards increased importance of sensitive small molluscs and tube-building annelids concurrent with a general temperature increase and reduction of nutrients in the water masses. The trend was largely similar over the stations, indicating that large-scale changes in the Skagerrak water masses were driving factors compared to possible influences from local sources. The faunal changes during the study period thus indicate an improved status of the soft bottom benthos, which possibly could be related to a reduction in the eutrophication. On a shorter scale, species richness was found to vary in relation to North Atlantic Oscillation (NAO) Index in the previous year (decline), nutrient concentrations in spring (decline), and winter water temperature (incline).

• Nyhagen, Fredrik Oulie; Christie, Hartvig & Norderhaug, Kjell Magnus (2018). Will altered climate affect a discrete population of the sea urchin Strongylocentrotus droebachiensis? Journal of Sea Research. ISSN 1385-1101. 132, p. 24–34. doi: 10.1016/j.seares.2017.12.001. Full text in Research Archive Show summary

  The Green sea urchin Strongylocentrotus droebachiensis is a cold-water species that in the 70s and 80s was the main culprit in the major grazing of macrophytes in the Norwegian fjords and coastal areas. Recent reports have questioned a decline in the S. droebachiensis in the Oslofjord, similar to what was observed to occur in the Norwegian coastal population of S. droebachiensis after the 1990s. In surveys from 2013 we collected data on urchin density, test diameter, early urchin settlement and Gonad Index and created a framework in order to investigate if the current Inner Oslofjord populations of S. droebachiensis are different from surveys conducted in 1979 and 1992. This study found significant differences in density, diameter and settlement over time. Highest density in 1992 was at 10 and 15 m, while being at 20 m in 2013. Urchin diameter at the station with most urchins was on average 5 cm in 1992 compared to 3 cm in 2013. Settlement differed both between the number of settlers between 1992 and 2013, and season for highest settlement (summer in 1992, and autumn in 2013). The inner Oslofjord sea urchin data indicate a still healthy population, although environmental data (as temperature and salinity) have changed to less favorable conditions for this species.

• Filbee-Dexter, Karen; Wernberg, Thomas; Norderhaug, Kjell Magnus; Ramirez-Llodra, Eva & Pedersen, Morten Foldager (2018). Movement of pulsed resource subsidies from kelp forests to deep fjords. Oecologia. ISSN 0029-8549. 187(1), p. 291–304. doi: 10.1007/s00442-018-4121-7. Full text in Research Archive Show summary

  Resource subsidies in the form of allochthonous primary production drive secondary production in many ecosystems, often sustaining diversity and overall productivity. Despite their importance in structuring marine communities, there is little understanding of how subsidies move through juxtaposed habitats and into recipient communities. We investigated the transport of detritus from kelp forests to a deep Arctic fjord (northern Norway). We quantified the seasonal abundance and size structure of kelp detritus in shallow subtidal (0‒12 m), deep subtidal (12‒85 m), and deep fjord (400‒450 m) habitats using a combination of camera surveys, dive observations, and detritus collections over 1 year. Detritus formed dense accumulations in habitats adjacent to kelp forests, and the timing of depositions coincided with the discrete loss of whole kelp blades during spring. We tracked these blades through the deep subtidal and into the deep fjord, and showed they act as a short-term resource pulse transported over several weeks. In deep subtidal regions, detritus consisted mostly of fragments and its depth distribution was similar across seasons (50% of total observations). Tagged pieces of detritus moved slowly out of kelp forests (displaced 4‒50 m (mean 11.8 m ± 8.5 SD) in 11‒17 days, based on minimum estimates from recovered pieces), and most (75%) variability in the rate of export was related to wave exposure and substrate. Tight resource coupling between kelp forests and deep fjords indicate that changes in kelp abundance would propagate through to deep fjord ecosystems, with likely consequences for the ecosystem functioning and services they provide.

• Araújo, Rita M. dos Santos Fernandes de; Assis, Jorge; Aguillar, Ricardo; Airoldi, Laura; Bárbara, Ignacio & Bartsch, Inka [Show all 27 contributors for this article] (2016). Status, trends and drivers of kelp forests in Europe: an expert assessment. Biodiversity and Conservation. ISSN 0960-3115. 25(7), p. 1319–1348. doi: 10.1007/s10531-016-1141-7. Full text in Research Archive
• Norderhaug, K. M.; d'Auriac, M. B. Angles; Fagerli, C. W.; Gundersen, H.; Christie, H. & Dahl, K. [Show all 7 contributors for this article] (2016). Genetic diversity of the NE Atlantic sea urchin Strongylocentrotus droebachiensis unveils chaotic genetic patchiness possibly linked to local selective pressure. Marine Biology. ISSN 0025-3162. 163(36). doi: 10.1007/s00227-015-2801-y. Full text in Research Archive Show summary

  We compared the genetic differentiation in the green sea urchin Strongylocentrotus droebachiensis from discrete populations on the NE Atlantic coast. By using eight recently developed microsatellite markers, genetic structure was compared between populations from the Danish Strait in the south to the Barents Sea in the north (56–79°N). Urchins are spread by pelagic larvae and may be transported long distances by northwards-going ocean currents. Two main superimposed patterns were identified. The first showed a subtle but significant genetic differentiation from the southernmost to the northernmost of the studied populations and could be explained by an isolation by distance model. The second pattern included two coastal populations in mid-Norway (65°N), NH and NS, as well as the northernmost population of continental Norway (71°N) FV. They showed a high degree of differentiation from all other populations. The explanation to the second pattern is most likely chaotic genetic patchiness caused by introgression from another species, S. pallidus, into S. droebachiensis resulting from selective pressure. Ongoing sea urchin collapse and kelp forests recovery are observed in the area of NH, NS and FV populations. High gene flow between populations spanning more than 22° in latitude suggests a high risk of new grazing events to occur rapidly in the future if conditions for sea urchins are favourable. On the other hand, the possibility of hybridization in association with collapsing populations may be used as an early warning indicator for monitoring purposes.

• Ramirez-Llodra, Eva; Rinde, Eli; Gundersen, Hege; Christie, Hartvig; Fagerli, Camilla With & Fredriksen, Stein [Show all 10 contributors for this article] (2016). A snap shot of the short-term response of crustaceans to macrophyte detritus in the deep Oslofjord. Scientific Reports. 6. doi: 10.1038/srep23800. Full text in Research Archive Show summary

  A test deployment of a time-lapse camera lander in the deep Oslofjord (431 m) was used to obtain initial information on the response of benthic fauna to macroalgal debris. Three macroalgal species were used on the lander baited plate: Fucus serratus, Saccharina latissima and Laminaria hyperborea and observed during 41.5 hours. The deep-water shrimp Pandalus borealis were attracted to the macroalgae rapidly (3 min after the lander reached the seafloor), followed by amphipods. Shrimp abundances were significantly higher in areas covered by macroalgae compared to the adjacent seafloor and the number of shrimp visiting the macroalgae increased with time. Amphipods arrived 13 hours later and were observed mainly on decaying L. hyperborea. The abundance of amphipods on L. hyperborea increased rapidly, reaching a peak at 31 h after deployment. These initial observations suggest that debris from kelp forests and other macroalgal beds may play an important role in fuelling deep benthic communities in the outer Oslofjord and, potentially, enhance secondary production of commercial species such as P. borealis.

• Christie, Hartvig & Norderhaug, Kjell Magnus (2016). Secondary production. In Olafsson, Emil (Eds.), Marine Macrophytes as Foundation Species. CRC Press. ISSN 9781315370781. p. 161–176. Full text in Research Archive
• Krumhansl, Kira A.; Okamoto, Daniel K.; Rassweiler, Andrew; Novak, Mark; Bolton, John J. & Cavanaugh, Kyle C. [Show all 37 contributors for this article] (2016). Global patterns of kelp forest change over the past half-century. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 113(48), p. 13785–13790. doi: 10.1073/pnas.1606102113. Full text in Research Archive
• Bekkby, Trine; Angeltveit, Gro; Gundersen, Hege; Tveiten, Lise Ann & Norderhaug, Kjell Magnus (2015). Red sea urchins (Echinus esculentus) and water flow influence epiphytic macroalgae density. Marine Biology Research. ISSN 1745-1000. 11(4), p. 375–384. doi: 10.1080/17451000.2014.943239. Full text in Research Archive Show summary

  The importance of forests of the kelp Laminaria hyperborea along the Norwegian coast is related to the three dimensional structure that they create together with the associated macroalgae. Today, kelp forests have recovered in several areas after an extensive overgrazing by green sea urchins (Strongylocentrotus droebachiensis). However, red sea urchins (Echinus esculentus) have been observed grazing on kelp and algae in recently recovered kelp forests. Apart from grazing pressure, the abundance of algae depends on environmental conditions, such as light and water flow. The main aim of this study was to analyse how densities of red sea urchins, wave exposure and current speed influence densities of epiphytic macroalgae associated with kelp stipes. Our results show that the density of red sea urchins had a negative effect on macroalgal densities. In the welldeveloped kelp forest (i.e. in a late successional stage found in the southern region), macroalgal density decreased with depth and increased with water flow, both in terms of waves and currents. Wave forces had a higher effect than tidal-driven currents. In the recently recovered kelp forests (in the northern region), we found lower densities of epiphytic macroalgae in shallow compared to deep waters, most likely caused by red sea urchin grazing. Our study concludes that water flow is important for the ecological function of the kelp forest through the influence on habitat-forming epiphytic macroalgae, and that grazing by red sea urchins might severely affect kelp forest resilience in recently recovered areas.

• Norderhaug, Kjell Magnus; Gundersen, Hege; Pedersen, Are; Moy, Frithjof Emil; Green, Norman Whitaker & Walday, Mats Gunnar [Show all 11 contributors for this article] (2015). Effects of climate and eutrophication on the diversity of hard bottom communities on the Skagerrak coast 1990-2010. Marine Ecology Progress Series. ISSN 0171-8630. 530, p. 29–46. doi: 10.3354/meps11306. Full text in Research Archive Show summary

  Eutrophication is one of the most serious environmental problems in the Skagerrak, and climate change may increase eutrophication in the future. This study focused on the effects of eutrophication and climate, and the interactions between these 2 factors, on biodiversity in rocky bottom communities on the outer Skagerrak coast. Monitoring data from the period 1990 to 2010 including macroalgae, sessile fauna and physical and hydrochemical data were analysed. In total, 45% of the total variance in the communities could be explained by physical factors and factors related to climate and eutrophication. The most important factors regulating species richness, diversity and community structure were wave exposure level and other factors varying with depth and biogeographical region. The benthic ecosystems were overall dominated by perennial and annual algae and rich communities of sessile macroinvertebrates. Climate variation and eutrophication variables had small but consistent impacts on the communities. Periods with high particle concentrations and with extreme temperatures negatively impacted benthic diversity. The responses to nutrients were variable and dependant on season and species. In January, when measurements best reflect available nutrients in the system, the species richness and diversity responses were concave, with the greatest richness and diversity in periods with intermediate nutrient concentrations. This pattern may indicate that our communities were in an elevated eutrophication state in periods with high nutrient concentrations and in the enrichment phase in periods with low concentrations. The study highlights the importance of regarding multiple stressors in combination and indicates that climate change may decrease benthic diversity in the Skagerrak in the future.

• Fagerli, Camilla With; Stadniczenko, Sandra Gran; Pedersen, Morten Foldager; Christie, Hartvig C; Fredriksen, Stein & Norderhaug, Kjell Magnus (2015). Population dynamics of Strongylocentrotus droebachiensis in kelp forests and barren grounds in Norway. Marine Biology. ISSN 0025-3162. 162(6), p. 1215–1226. doi: 10.1007/s00227-015-2663-3. Full text in Research Archive
• Ling, Scott D.; Scheibling, Robert E.; Rassweiler, Andrew; Johnson, Craig R.; Shears, Nick T. & Connell, Sean D. [Show all 20 contributors for this article] (2015). Global regime shift dynamics of catastrophic sea urchin overgrazing. Philosophical Transactions of the Royal Society of London. Biological Sciences. ISSN 0962-8436. 370(1659), p. 1–10. doi: 10.1098/rstb.2013.0269. Full text in Research Archive
• Rinde, Eli; Christie, Hartvig C; Fagerli, Camilla With; Bekkby, Trine; Gundersen, Hege & Norderhaug, Kjell Magnus [Show all 7 contributors for this article] (2014). The influence of physical factors on kelp and sea urchin distribution in previously and still grazed areas in the NE Atlantic. PLOS ONE. 9(6). doi: 10.1371/journal.pone.0100222. Full text in Research Archive Show summary

  The spatial distribution of kelp (Laminaria hyperborea) and sea urchins (Strongylocentrotus droebachiensis) in the NE Atlantic are highly related to physical factors and to temporal changes in temperature. On a large scale, we identified borders for kelp recovery and sea urchin persistence along the north-south gradient. Sea urchin persistence was also related to the coast-ocean gradient. The southern border corresponds to summer temperatures exceeding about 10 C, a threshold value known to be critical for sea urchin recruitment and development. The outer border along the coast-ocean gradient is related to temperature, wave exposure and salinity. On a finer scale, kelp recovery occurs mainly at ridges in outer, wave exposed, saline and warm areas whereas sea urchins still dominate in inner, shallow and cold areas, particularly in areas with optimal current speed for sea urchin foraging. In contrast to other studies in Europe, we here show a positive influence of climate change to presence of a long lived climax canopy-forming kelp. The extent of the coast ocean gradient varies within the study area, and is especially wide in the southern part where the presence of islands and skerries increases the area of the shallow coastal zone. This creates a large area with intermediate physical conditions for the two species and a mosaic of kelp and sea urchin dominated patches. The statistical models (GAM and BRT) show high performance and indicate recovery of kelp in 45–60% of the study area. The study shows the value of combining a traditional (GAM) and a more complex (BRT) modeling approach to gain insight into complex spatial patterns of species or habitats. The results, methods and approaches are of general ecological relevance regardless of ecosystems and species, although they are particularly relevant for understanding and exploring the corresponding changes between algae and grazers in different coastal areas.

• d'Auriac, Marc Angles; Hobæk, Anders; Christie, Hartvig C; Gundersen, Hege; Fagerli, Camilla With & Haugstetter, Johannes [Show all 7 contributors for this article] (2014). New microsatellite loci for the green sea urchin Strongylocentrotus droebachiensis using universal M13 labelled markers. BMC Research Notes. 7(1). doi: 10.1186/1756-0500-7-699. Full text in Research Archive

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• Norderhaug, Kjell Magnus; Haugland, Barbro Taraldset; Gulliksen, Bjørn; Gonzalez-Mirelis, Genoveva; Ross, Rebecca & Tandberg, Anne Helene S. [Show all 7 contributors for this article] (2025). Rødlista – marint gruntvann | Artsdatabanken. doi: https:/artsdatabanken.no/Naturtyper/Rodlista-naturtyper/Om-Rodlista/Vurderte-naturtyper/Rodlista-marint-gruntvann. Full text in Research Archive Show summary

  Oppdatering av rødlistene for marine dyphavs-habitater (iflg NiN 3.0) iflg IUCN sine kriterier.

• Norderhaug, Kjell Magnus; Haugland, Barbro Taraldset; Gulliksen, Bjørn; Gonzalez-Mirelis, Genoveva; Ross, Rebecca & Tandberg, Anne Helene S. [Show all 7 contributors for this article] (2025). Rødlista – marint dypvann | Artsdatabanken. doi: https:/artsdatabanken.no/Naturtyper/Rodlista-naturtyper/Om-Rodlista/Vurderte-naturtyper/Rodlista-marint-dypvann. Full text in Research Archive Show summary

  Oppdatering av rødlistene for marine dyphavs-habitater (iflg NiN 3.0) iflg IUCN sine kriterier.

• Gagnon, Karine; Thormar, Jonas; Fredriksen, Stein; Potouroglou, Maria; Albretsen, Jon & Gundersen, Hege [Show all 10 contributors for this article] (2024). Carbon storage capacity of Norwegian eelgrass meadows across environmental gradients. Full text in Research Archive
• Norderhaug, Kjell Magnus; Nedreaas, Kjell Harald; Huserbråten, Mats Brockstedt Olsen & Moland, Even (2023). Overfishing caused the largest sea urchin grazing event observed in the NE Atlantic. Full text in Research Archive
• Wernberg, Thomas; Filbee-Dexter, Karen; Norderhaug, Kjell Magnus & Hancke, Kasper (2023). The Value of the World’s Kelp Forests. Full text in Research Archive
• Zimmerhanckle, Johanna; Filbee-Dexter, Karen; Norderhaug, Kjell Magnus & Wernberg, Thomas (2023). Valuation methods and evidence for ecosystem services from kelp forests. Full text in Research Archive
• Pineiro-Corbeira, Cristina; Norderhaug, Kjell Magnus; Filbee-Dexter, Karen & Wernberg, Thomas (2023). The value of kelp forests for supporting fisheries. Full text in Research Archive
• Norderhaug, Kjell Magnus (2022). Macroalgae aquaculture - A new blue industry in Norway. Full text in Research Archive
• Norderhaug, Kjell Magnus (2022). Den blå skogen er viktigere enn du tror. Full text in Research Archive
• Gundersen, Hege; Hancke, Kasper & Norderhaug, Kjell Magnus (2022). Ecosystem services of kelp in Scandinavia. Full text in Research Archive
• Wathne, Cecilie Linn; Sander, Gunnar; Gundersen, Hege; Norderhaug, Kjell Magnus; Lutz, Steven & Bryan, Tanya (2021). Våre blå skoger er i dårlig tilstand. Full text in Research Archive
• Bekkby, Trine; Andersen, Guri Sogn; Angeltveit, Gro; Broch, Ole Jacob; Bøe, Reidulv & Christie, Hartvig C [Show all 21 contributors for this article] (2019). Added values from the large-scale and long-lasting program for mapping marine habitats. Full text in Research Archive
• Bekkby, Trine; Christie, Hartvig C; Norderhaug, Kjell Magnus; Beyer, Jonny & Jørgensen, Nina Mari (2019). Sea urchin grazing of kelp forests in the Arctic and the impact on the recovery of rocky shore communities after oil spills. Full text in Research Archive
• Torp, ØH; Fagerli, Camilla With; Fredriksen, Stein; Hancke, Kasper & Norderhaug, Kjell Magnus (2018). Factors affecting Saccharina latissima, concerning growth, recruitment and competition. Full text in Research Archive
• Gundersen, Hege; Bekkby, Trine; Norderhaug, Kjell Magnus & Oug, Eivind (2018). Marint gruntvann. Full text in Research Archive
• Thormar, Jonas; Steen, Henning; Son, Thijs Christiaan van; Bosgraaf, Sebastian; Christensen, Lene & Mellerud, Ida Kristin [Show all 8 contributors for this article] (2017). Fish Assemblages in Coastal Vegetation. Full text in Research Archive
• Fagerli, Camilla With; Stadniczenko, Sandra Gran; Pedersen, Morten foldager; Christie, Hartvig C; Fredriksen, Stein & Norderhaug, Kjell Magnus (2016). Are skeletal ossicles in echinoids unreliable chronometers? Reply to Russell and Narváez comment on “Population dynamics of Strongylocentrotus droebachiensis in kelp forests and barren grounds in Norway” by Fagerli et al. 2015. Marine Biology. ISSN 0025-3162. 163(7), p. 160–161. doi: 10.1007/s00227-016-2928-5. Full text in Research Archive
• Gundersen, Hege; Norderhaug, Kjell Magnus & Borchgrevink, Harald Bonaventura (2016). Overgjødsling og varmere vann kan bety trøbbel i Skagerrak. [Internet]. forskning.no. Full text in Research Archive
• Gitmark, Janne Kim; Norderhaug, Kjell Magnus; Rinde, Eli; Gundersen, Hege; Christie, Hartvig C & Bekkby, Trine (2016). Effect of wave exposure and current speed on kelp morphology and the associated fauna communities. Full text in Research Archive
• Bekkby, Trine; Rinde, Eli; Norderhaug, Kjell Magnus; Fagerli, Camilla With; Angeltveit, Gro & Gitmark, Janne Kim [Show all 9 contributors for this article] (2016). Interactive dynamics between abiotic factors, sea urchins and kelp forests. Full text in Research Archive
• Norderhaug, Kjell Magnus & Gundersen, Hege (2016). National report status. Presentation at OSPAR working group meeting. Full text in Research Archive
• Gundersen, Hege; Norderhaug, Kjell Magnus; Rinde, Eli; Johnsen, Torbjørn Martin; Meeren, Gro Ingleid van der & Nilssen, Kjell Tormod [Show all 7 contributors for this article] (2015). Kyst. In Framstad, Erik (Eds.), Naturindeks for Norge 2015. Tilstand og utvikling for biologisk mangfold. Miljødirektoratet. p. 50–58. Full text in Research Archive Show summary

  Naturindeksen viser tilstand og utvikling for biologisk mangfold i Norge ved å sammenfatte informasjon om 301 indikatorer fra ni hovedøkosystemer. De fleste indikatorene representerer bestander for karakteristiske stedegne arter i disse økosystemene. Informasjonen om indikatorene er basert på data fra overvåking, modellestimater og ekspertvurderinger. Indikatorverdiene er skalert mot sin verdi i en referansetilstand med tilnærmet intakt biologisk mangfold. Naturindeksen viser store forskjeller i tilstand for biologisk mangfold mellom økosystemene. Verdien av naturindeksen er høyest for ferskvann og de marine økosystemene og lavest for skog og åpent lavland. Naturindeksen viser klarest tilbakegang for våtmark og åpent lavland, mens marine pelagiske økosystemer har vist framgang. Også skog viser en svak framgang. Indikatorene i naturindeksen er særlig følsomme for påvirkning fra beskatning og klima i de marine økosystemene og fra arealbruk i de øvrige økosystemene. Indikatorene omfatter også 154 arter av nasjonal forvaltningsinteresse. Naturindeksens rammeverk og indikatorer kan også brukes til å belyse utviklingen for ulike økosystemtjenester som er viktige for menneskers velferd. Biologisk mangfold, tilstand, økosystemer, naturindeks, Biodiversity, state, ecosystems, nature index

• Gundersen, Hege; Norderhaug, Kjell Magnus; Rinde, Eli; Johnsen, Torbjørn Martin; Meeren, Gro Ingleid van der & Nilssen, Kjell Tormod (2015). Kystøkosystemet. Full text in Research Archive
• Norderhaug, Kjell Magnus; Bekkby, Trine & Christie, Hartvig (2015). Kystøkosystemer i endring. Full text in Research Archive
• Bekkby, Trine; Rinde, Eli; Norderhaug, Kjell Magnus; Angeltveit, Gro; Gitmark, Janne K. & Gundersen, Hege [Show all 8 contributors for this article] (2015). Understanding variation and changes in kelp forest ecosystems using modelling approaches. Full text in Research Archive
• Angeltveit, Gro; Bekkby, Trine; Gundersen, Hege; Tveiten, Lise Ann & Norderhaug, Kjell Magnus (2015). Vannbevegelse og kråkeboller påvirker tareskogen. Naturen. ISSN 0028-0887. 1, p. 37–41. Full text in Research Archive Show summary

  Tareskogen er et svært produktivt og viktig økosystem. På tarestilken vokser store mengder alger («påvekstalger»), hvilket gir stortareskogen en unik, tredimensjonal struktur. Disse tareskogene kalles «havets regnskog» på grunn av den store artsrikdommen. I flere tiår har store deler av tareskogen langs norskekysten vært nedbeitet av den grønne kråkebollen (Strongelyocentrotus droebachiensis). «Havets regnskog» forsvant og ble erstattet av en «ørken» av stein, der bare grønne kråkeboller levde. En mulig årsak til dette kan være kaldtvannsperioden på 1960-tallet kombinert med det store fiskepresset i samme periode. I dag er tareskogene på vei tilbake og selve stortaren (Laminaria hyperborea) har god gjenvekst i Trøndelag og Nordland. Men er den like artsrik som før? For å fungere som en artsrik «regnskog» trenger tareskogen algene som vokser på stilkene. Den røde kråkebollen (Echinus esculentus) spiser alger på taren. I ung tareskog har denne få naturlige fiender og opptrer i større antall enn i gammel, etablert tareskog. Dette reduserer den økologiske stabiliteten i ung tareskog og gjør den mer sårbar. I tillegg til beiting fra de røde kråkebollene, påvirker vannets bevegelse, det vil si bølger og strøm, mengden påvekstalger på stortarestilken ved å bevege tarebladene slik at lys og næringsstoffer slipper til, samt ved å øke algenes evne til å ta opp næringsstoffer.

• Fagerli, Camilla With; Norderhaug, Kjell Magnus; Christie, Hartvig C; Rinde, Eli; Bekkby, Trine & Gundersen, Hege [Show all 7 contributors for this article] (2015). Gjenvekst i tareskog – en positiv effekt av klimaendringer. Naturen. ISSN 0028-0887. 3, p. 134–139. Full text in Research Archive
• Bekkby, Trine; Gundersen, Hege; Rinde, Eli; Norderhaug, Kjell Magnus; Gitmark, Janne Kim & Christie, Hartvig C (2014). Effekten av bølger og strøm på stortarens morfologi. VANN. ISSN 0042-2592. 2, p. 215–222. Full text in Research Archive Show summary

  Vannbevegelse har stor påvirkning på tare, både negativt ved å skade eller rive løs planten og positivt ved å forbedre lysforhold og karbon- og næringsopptak. Vi har studert hvordan bølgeeksponering og strømhastighet virker sammen på stortarens (Laminaria hyperborea) morfologi. Vi samlet inn tareplanter på 27 stasjoner på Mørekysten og registrerte alder og egenskaper knyttet til tarens lengde og styrke. Vi fant at høy grad av vannbevegelse (både i form av bølger og strøm) påvirket tarestilkens tykkelse og festeorganets (som fester taren til underlaget) vekt. Bølgeeksponeringen hadde større effekt enn strøm, og strøm hadde større effekt ved lave enn ved høye nivåer av bølgeeksponering. Stilklengden var påvirket av bølgeeksponering, men ikke av strøm. Våre resultater antyder at den sterke, orbitale og stokastiske formen for bevegelse som kommer fra bølger har en større effekt enn det jevne draget fra strøm.

• Steen, Henning; Kartveit, Kyrre Heldal; Dupont, Nicolas & Norderhaug, Kjell Magnus (2025). Tareundersøkelser i Nordland 2020-24 |. Havforskningsinstituttet. Full text in Research Archive Show summary

  Havforskningsinstituttet har i perioden 2020-24 gjennomført undersøkelser av taresamfunn på kyststrekningen Bindal (65° 13’ N) – Vega (65° 33’ N) i Nordland. Deler av denne kyststrekningen ble åpnet for kommersiell høsting av stortare (Laminaria hyperborea) i 2022, etter en prøvehøstingsperiode i 2013-17. Effekter av den tidligere prøvehøstingen på taresamfunn og kråkebolleforekomster ble undersøkt ved hjelp av undervannsvideo langs transekter og innsamlinger av tareplanter på utvalgte stasjoner for studier av morfologi, alder, assosiert biomangfold (epifyttsamfunn) og kråkebollerekruttering. Resultatene fra disse undersøkelsene indikerer at stortarevegetasjonens størrelse og biomasse er reetablert 5 år etter høsting, mens begroingssamfunnene (epifyttene) knyttet til tarestilkene er reetablert 8 år etter høsting og da lik tilsvarende observert i uhøstede referanseområder. Resultatene tyder på at forekomstene av kråkeboller er på et moderat nivå og at reetableringen av tare på høstefeltene ikke har vært hemmet av kråkebollebeiting.

• Skern-Mauritzen, Mette; Jørgensen, Lis Lindal; Kleiven, Alf Ring; Meeren, Gro Ingleid van der; Meeren, Terje van der & Moland, Even [Show all 9 contributors for this article] (2025). Naturavtalens Mål 3 om vern og beskyttelse – krav til implementering i en norsk marin kontekst. Havforskningsinstituttet. Full text in Research Archive Show summary

  På oppdrag fra Fiskeridirektoratet vurderer vi i denne rapporten spesifikt hvordan Mål 3 i Naturavtalen, som etablerer globale mål for vern og bevaring av marint naturmangfold med tilhørende krav, kan forstås og operasjonaliseres i en norsk kontekst for å realisere Naturavtalens overordnede mål. Videre presenterer vi en prosess for identifisering av kandidatområder for vern og bevaring i tråd med kravene i Mål 3, samt identifiserer relevante datakilder og kunnskapsgrunnlag. Vurderingen fokuserer særlig på krav som omhandler økologiske og biologiske elementer, og prosesser, som faller inn under Havforskningsinstituttets kompetanseområder.

• Norderhaug, Kjell Magnus; Wathne, Cecilie Linn; Filbee-Dexter, Karen; Rogne, Sissel; Strand, Hans Kristian & Wernberg, Thomas [Show all 13 contributors for this article] (2025). Restaurering av tareskog i Norge — Rapport I - Statusrapport. Havforskningsinstituttet. Full text in Research Archive Show summary

  Den 14. juni 2024 fattet Stortingets anmodningsvedtak 789: «Stortinget ber regjeringen legge frem en plan og foreslå tiltak for å systematisk restaurere norsk tareskog langs kysten for å bedre det marine miljø.». Vedtaket følges opp av Nærings- og fiskeridepartementet (NFD) i samarbeid med Klima- og Miljødepartementet (KLD). Oppdraget er gitt til Havforskningsinstituttet i tildelingsbrevet for 2025. Det skal løses i samarbeid med Fiskeridirektoratet.

• Kleiven, Alf Ring; Thorstensen, Helene Skjeie; Norderhaug, Kjell Magnus; Meeren, Gro Ingleid van der; Dunlop, Katherine Mary & Thorbjørnsen, Susanna Huneide [Show all 12 contributors for this article] (2024). Hvor godt fungerer marine bevaringsområder? En litteraturstudie. SALT Rapport nr. 1090. Full text in Research Archive Show summary

  SALT og Havforskningsinstituttet har på oppdrag fra Miljødirektoratet utarbeidet en «Kunnskapssyntese om virkninger av marine verneområder for økosystemfunksjon og potensial for høsting i omkringliggende områder» (saksnummer 2024/3032). Med bakgrunn i Stortingsmeldingen Heilskapleg nasjonal plan for bevaring av viktige område for marin natur har regjeringen et uttalt mål om å styrke kunnskapen om effekter av marine verneområder i Norge, og ønsker å få gjennomført en kunnskapssyntese om virkninger av marine verneområder for økosystemfunksjon og muligheter for høsting av levende ressurser i omkringliggende områder.

• Kleiven, Alf Ring; Thorbjørnsen, Susanna Huneide; Meeren, Gro Ingleid van der; Freitas, Carla; Naustvoll, Lars Johan & Moland, Even [Show all 11 contributors for this article] (2024). Raet nasjonalpark — Kunnskap og råd for bevaring av marint naturmangfold. Havforskningsinstituttet. Full text in Research Archive Show summary

  På oppdrag for prosjektet «Bevar Raet» har av forskningsinstituttet utarbeidet en rapport om kunnskapsstatus for sjøområdene i og rundt Raet nasjonalpark. Formålet med rapporten er å bidra med et kunnskapsgrunnlag for at det marine økosystemet i Raet nasjonalpark kan gjenoppbygges til et robust nivå. Rapporten viser at Raet nasjonalpark per i dag kan klassifiseres som «ubeskyttet». Ut i fra dagens restriksjonsnivå kan det ikke forventes positive effekter på alders- og størrelsessammensetning, biomasse, biologisk mangfold samt robusthet mot klimaendringer. Raet nasjonalpark er derfor ikke regulert slik at det kan fungere etter hensikten med å bevare plantelivet, dyrelivet og naturtyper. Ved å dele opp Raet nasjonalpark i soner med ulik grad av beskyttelse (spesielt regulering av fiskeri) vil det være mulig å oppnå effektiv bevaring av naturmangfoldet. Samtidig bør det rettes økt fokus på vannkvalitet i indre kystområder, både med tanke på overvåkning og tiltak.

• Aarflot, Johanna Myrseth; Naustvoll, Lars Johan; Moy, Frithjof Emil; Norderhaug, Kjell Magnus; Berg, Florian & Kvamme, Cecilie [Show all 12 contributors for this article] (2024). Pilotprosjekt for vurdering av samlet påvirkning i Oslofjorden – ytre del. Havforskningsinstituttet. Full text in Research Archive Show summary

  Stor befolkningstetthet, høy menneskelig aktivitet og miljøutfordringer gjør at det er viktig å vurdere menneskelig påvirkning i Oslofjorden samlet. Denne rapporten presenterer en tverrsektoriell fremstilling av samlet påvirkning i et avgrenset område i ytre deler av fjordsystemet, som inkluderer Ytre Hvaler og Færder Nasjonalparker. Arbeidet omfatter en gjennomgang av menneskelig aktivitet (f.eks. fiskeri, turisme, avløp) som kan legge press på ulike deler av det marine økosystemet, og som kan forvaltes i dag. Risiko for negativ påvirkning vurderes basert på hvor eksponert økosystemkomponenter er for påvirkninger, og hvilken effekt påvirkningene er forventet å gi. Dette gir en systematisk evaluering av informasjon fra mange kilder, som kombinert med ekspertvurderinger benyttes til å vekte større og mindre viktige påvirkninger og fremstille risiko på tvers av økosystemet. Formålet er å danne et felles grunnlag for diskusjon om helhetlig, direkte, negativ påvirkning på økosystemet sett på tvers av sektorer og forvaltningsansvar. Metoden som benyttes i denne rapporten har tidligere blitt benyttet i flere andre risikovurderinger for marine økosystem både i Norge og internasjonalt, både i regi av ICES, OSPAR og gjennom en rekke forskningsprosjekter. Metoden er hentet fra et tidligere EU-prosjekt, Options for Delivering Ecosystem-based Marine Management (ODEMM), og kalles gjerne «ODEMM-metoden» eller «CoastRisk-metoden» da den også ble benyttet i CoastRisk-prosjektet (2019-2024). Vurdering av risiko basert på hvor eksponert deler av økosystemet er og hvilken effekt en påvirkning kan ha, anses som en mer fornuftig tilnærming for å vurdere risiko fra aktiviteter som allerede foregår i et område, sammenlignet med sannsynlighet × konsekvens som er det mange er vant til å forbinde med risikobegrepet. Akuttutslipp og uhells-hendelser inngår ikke i vurderingene her, og vi har tatt utgangspunkt i den type aktivitet som vil oppstå i løpet av et normalår, fortrinnsvis årene 2022-2023 der hvor data har vært tilgjengelig. Høsting, miljøgifter, mikroplast, fysisk påvirkning og næringssalter er de 5 påvirkningene som gir størst bidrag til risiko fra samlet påvirkning, i sum bidrar disse til over 70 % av den totale risikoscoren for området. Dette er påvirkninger som anses å ha forholdsmessig vid utbredelse i området, tilføres regelmessig ila. et normalår, knyttes til flere sektorer og har kronisk til akutt effekt på flere økosystemkomponenter. Skalldyr, bunnfisk, ålegress, bløtbunnsfauna og tidlige livsstadier fisk er økosystemkomponentene med høyest risiko for en samlet negativ påvirkning. Flere av økosystemkomponentene er heterogene grupper (f.eks. skalldyr, bunnfisk) og risikoen vil variere avhengig av undergruppe og levested. En evaluering av konfidens for de vurderingene som er gjort viser at det er generelt høy konfidens for at økosystemkomponenter er eksponert for høsting og næringssalter, men lavere konfidens knyttet til miljøgifter og mikroplast. De to sistnevnte er også persistente påvirkninger som ikke forventes å forlate økosystemet de neste 100 årene, noe som kan gi akkumulerte effekter over tid og er særlig viktig for bærekraftig forvaltning av menneskelig påvirkning. Vi har også foretatt en grovskala vurdering av resiliensen til økosystemkomponenter, dvs. hvor lang tid det forventes å ta for en økosystemkomponent å bygge seg opp igjen etter en negativ påvirkning. Bunnfisk, sjøfugl, ålegress, sjøpattedyr og hardbunnsfauna (koraller) er økosystemkomponentene vurdert å ha lavest resiliens i dette området.

• Marquez, Jonatan Fredricson; Meeren, Gro Ingleid van der; Meeren, Terje van der; Albretsen, Jon; Ross, Rebecca & Steen, Henning [Show all 43 contributors for this article] (2024). Liste over forvaltningsrelevante naturenheter - Oppfølgende informasjon til rapporten "Forvaltningsrelevante naturenheter i sjø". Havforskningsinstituttet. Full text in Research Archive Show summary

  I forbindelse med forvaltningens oppgave om å lage en framtidig samlet offentlig instruks for kartlegging av marin natur, bestilte fiskeridirektoratet i en oversikt over der havforskningsinstituttet ville foreslå som "Forvaltningsrelevante naturenheter i sjø". Denne rapporten ble levert og publisert 29.04.2024. I den rapporten foreslo Havforskningsinstituttet å utvide begrepet naturenheter til også å omfatte funksjonsområder for arter, og områder viktig for struktur og sentrale økosystemprosesser. Totalt ble det foreslått 20 abiotiske fysiske enheter, 3 biotiske fysiske enheter, 6 hovedgrupper av funksjonsområder (for totalt 46 arter) og 9 struktur og prosessområder som kunne danne grunnlag for kartlegging av marin natur. Denne rapporten er en utdyping av rapporten "Forvaltningsrelevante naturenheter i sjø", der alle naturenhetene som er foreslått blir nærmere forklart samt at det presenteres et perspektiv på ulike aspekter som kan være viktig for prioritering av hva som skal kartlegges. Enkelte naturenheter har fått mindre endringer i navn og innhold til det opprinnelige forslaget, men den første rapporten har vært førende for innhold. Det kan være aktuelt å revidere hvilke naturenheter som vil være viktige og om noen naturenheter ikke nødvendigvis har samme betydning for forvaltningen på et senere tidspunkt.

• Cavanaugh, K; Krumhansl, Kira; Buschmann, AH; Wernberg, Thomas; Beas-Luna, R & Bekkby, Trine [Show all 16 contributors for this article] (2023). Chapter 2 Status, trends and future projections. Into the Blue: Securing a Sustainable Future for Kelp Forests. United Nations Environment Programme, 144 p. United Nations Environment Programme Report DEP/2505/NA, ISBN 978-92-807-4007-3. United Nations Environment Programme Report. Full text in Research Archive
• Steen, Henning; Christensen, Lene & Norderhaug, Kjell Magnus (2023). Tilstandsvurdering av Høstefelt for Stortare i Rogaland og Vestland i 2023. Havforskningsinstituttet. Full text in Research Archive Show summary

  Havforskningsinstituttet gjennomførte i april-mai 2023 video- og akustikkundersøkelser av A-felt for stortarehøsting i Rogaland og Vestland fylker, et snaut halvår før disse feltene er planlagt åpnet for tarehøsting i perioden 1. september 2023 – 31 august 2024. Tilsvarende undersøkelser ble også gjennomført på referansestasjoner i områder der tarehøsting ikke er tillatt. På bakgrunn av tarevegetasjonens tilstand gjøres en vurdering av hvert enkelt felts egnethet for tarehøsting kommende sesong. Selv om stortare dominerte bunnfloraen på de fleste stasjoner, ble det observert til dels store geografiske variasjoner i vegetasjonshøyde og biomassetetthet. På grunn av lav biomassetetthet av stortare frarådes tarehøsting på felt 51A (i Rogaland) og feltene 81A, 96A og 106A (i Vestland) i 2023/24. På enkelte stasjoner ble det også tatt prøver som indikerer at stortareplantene samlet inn i områder høstet 4 år tidligere ikke er størrelsesmessig forskjellig, men er yngre, har mindre festeorgan og påvekst av epifytter, enn plantene samlet inn i referanseområder. På grunn av lav biomassetetthet med betydelig innslag av unge, lite utviklede stortareplanter frarådes høsting på felt 46A (i Rogaland) og 161A (i Vestland) før 01.05.2024. Tettheten av kråkeboller var gjennomgående lav og stortarevegetasjons tilstand på øvrige undersøkte A-felt i Rogaland og Vestland anses som tilstrekkelig god til å kunne åpnes for tarehøsting 1 september 2023.

• Potouroglou, Maria; Filbee-Dexter, Karen; Lutz, Steven; Grimsditch, Gabriel; Jonsson, Linda & Sander, Gunnar [Show all 60 contributors for this article] (2023). Into the Blue: Securing a Sustainable Future for Kelp Forests. GRID-Arendal. ISSN 9789280740073. Full text in Research Archive
• Albretsen, Jon; Arneberg, Per; Assmann, Karen; Assmy, Philipp; Bohlin-Nizzetto, Pernilla & Børsheim, Knut Yngve [Show all 49 contributors for this article] (2023). Status for miljøet i norske havområder - Rapport fra Overvåkingsgruppen 2023. Havforskningsinstituttet. Full text in Research Archive Show summary

  I denne rapporten gir Overvåkingsgruppen, for første gang, en felles vurdering av miljøtilstanden i Barentshavet og havområdene utenfor Lofoten, Norskehavet og Nordsjøen med Skagerrak. Det er også første rapport som bruker resultater fra det nylig utviklede fagsystemet for vurdering av økologisk tilstand. I denne rapporten dekkes to hovedtemaer: (1) Dominerende trekk i status og utvikling i økosystemet i alle tre havområdene, basert på vurderingene av økologisk tilstand, Overvåkingsgruppens rapport om forurensning fra 2022, indikatorer fra Overvåkingsgruppen som ikke er dekket under vurdering av økologisk tilstand, samt rapporter og annen relevant informasjon fra forskning, og (2) en vurdering av karbonbinding i marint plankton, marine vegetasjonstyper og marine sedimenter. I tillegg er det gitt en oppsummering for endringer i ytre påvirkning, vurdering av kunnskapsbehov samt en vurdering av indikatorverdier i forhold til referanseverdier og tiltaksgrenser. Vurderingen av dominerende trekk i utvikling og tilstand av miljøet som er gitt i kapittel 2, utgjør Overvåkingsgruppens bidrag til Faglig forums samlerapport om det faglige grunnlaget for revisjon og oppdatering av de helhetlige forvaltningsplanene for norske havområder.

• Løkkeborg, Svein; Bakkeplass, Kjell Gunnar; Diesing, Markus; Gjøsæter, Harald; Gonzalez-Mirelis, Genoveva & Hvingel, Carsten [Show all 10 contributors for this article] (2023). Effekter av bunntråling - Sammenstilling av kunnskap om bunnpåvirkning fra trål og snurrevad relevant for norske farvann. Havforskningsinstituttet. Full text in Research Archive Show summary

  Rapporten gir en sammenstilling av publisert kunnskap om hvordan bunnhabitater og bunndyr påvirkes (fysiske, kjemiske og biologiske effekter) av fiske med bunntrål og snurrevad. Det legges hovedvekt på påvirkninger fra fisketrål og reketrål som er relevant for norske forhold. Rapporten beskriver utbredelsen av sårbare habitater i norske havområder, og det presenteres kart som viser hvor det fiskes med fisketrål, reketrål og snurrevad. Bunntråling er den menneskelige aktiviteten som i geografisk utstrekning har størst påvirkning på havbunnen.

• Espeland, Sigurd Heiberg; Norderhaug, Kjell Magnus; Thormar, Jonas; Kleiven, Portia Joy Nillos; Aanonsen, Inger Aline Norberg & Saltskår, Jostein [Show all 11 contributors for this article] (2022). Metoder for kartlegging av oppvekstområder for kystnære bestander av fisk. Havforskningsinstituttet. Full text in Research Archive Show summary

  Program for kartlegging av gyte- og oppvekstområder for kommersielt viktige arter i kystsonen» vil gjennom prosjektperioden kartlegge fisk i ulike habitater for å avgjøre hva som utgjør viktige oppvekstområder for fisk på kysten an Norge. Fiskeyngel har vært registrert i 4 ulike områder i kystsonen fra sør til nord i Norge på tvers av et bredt utvalg av miljøparametere og habitater. Betydelig utvikling har vært nødvendig for å finne egnede metoder for representativ innsamling av yngel og denne rapporten dokumenterer metoder brukt i prosjektet.

• Norderhaug, Kjell Magnus; Freitas, Carla; Espeland, Sigurd Heiberg; Albretsen, Jon; Christensen-Dalsgaard, Signe & Ohldieck, Martin Junker [Show all 10 contributors for this article] (2021). Bærekraftig taretråling - Vurdering av bærekraftskriterier ved Vikna. Havforskningsinstituttet. Full text in Research Archive
• Moland, Even; Synnes, Ann-Elin; Naustvoll, Lars Johan; Freitas, Carla; Norderhaug, Kjell Magnus & Thormar, Jonas [Show all 15 contributors for this article] (2021). Krafttak for kysttorsken - Kunnskap for stedstilpasset gjenoppbygging av bestander, naturtyper og økosystem i Færder- og Ytre Hvaler nasjonalparker. Havforskningsinstituttet. Full text in Research Archive Show summary

  Ytre Oslofjord har en unik kystnatur av svært stor verdi for både fastboende og tilreisende. Færder- og Ytre Hvaler nasjonalparker ligger side om side ytterst i fjorden, og skal sikre naturverdiene for kommende generasjoner. Nasjonalparkene har utformet egne forvaltningsplaner og -mål, som gjenspeiler et ønske om å legge best mulig til rette for at fiskearter, fugler, planter og insekter skal fortsette å trives innenfor parkenes grenser. Generelle mål for naturverdiene er at de skal opprettholdes med god økologisk funksjon, og et høyt biologisk mangfold.

• Norderhaug, Kjell Magnus; Hansen, Pia Kupka; Fredriksen, Stein; Grøsvik, Bjørn Einar; Naustvoll, Lars Johan & Steen, Henning [Show all 7 contributors for this article] (2021). Miljøpåvirkning fra dyrking av makroalger — Risikovurdering for norske farvann. Havforskningsinstituttet. Full text in Research Archive Show summary

  Det er økende interesse for makroalgedyrking, og miljøforholdene langs norskekysten er godt egnet for denne type akvakultivering. Denne rapporten beskriver et faggrunnlag for forvaltning av tillatelser for makroalgekultivering og gir risikovurderte råd i forhold til miljøpåvirkningen fra algedyrkingsanlegg på dagens produksjonsnivå og ved en forventet framtidig oppskalering av aktiviteten i norske farvann. Det anbefales at forvaltningen av algedyrking tilpasses miljøpåvirkningen den representerer og som i vesentlige henseender skiller seg fra fiskeoppdrett med generelt mindre miljøpåvirkning. Begrenset erfaringsbakgrunn gjør at det er generelt sparsom kunnskap om miljøeffektene fra algedyrkingsanlegg, spesielt store anlegg som foreløpig ikke er tatt i bruk i Norge. Samlet sett vurderes spredning av fremmede arter som den største trusselen mot miljøet. Det største kunnskapsbehovet er knyttet til spredning av arter, inkludert fremmede arter, mikroorganismer og sykdommer, og gener.

• Bettignies, Thibaut de; Bettignies, Florian de; Bartsch, Inka; Bekkby, Trine; Boiffin, A & Amezúa, P Casado de [Show all 35 contributors for this article] (2021). Background Document for Kelp Forests habitat. OSPAR. Full text in Research Archive Show summary

  This Background Document on Kelp Forest habitat has been developed by OSPAR following the inclusion of this species on the OSPAR List of threatened and/or declining species and habitats (OSPAR Agreement 2008-6). The inclusion of the feature on the list was supported by an analysis against the Texel-Faial criteria (OSPAR Agreement 2019-03), as presented in the case report (publication 358/2008). This Background Document provides proposals for action and includes measures that could be taken to improve the conservation status of the species. In agreeing to the publication of this document the OSPAR Contracting Parties have indicated the need to further review these proposals. However, the publication of this background document does not imply any formal endorsement of these proposals by the OSPAR Commission. On the basis of the further review of these proposals, OSPAR will continue its work to ensure the protection of Kelp Forest habitat, where necessary in cooperation with other competent organisations. This background document may be updated to reflect further developments or additional information that become available on the status of the species.

• Norderhaug, Kjell Magnus; Son, Thijs Christiaan van; Nikolioudakis, Nikolaos; Thormar, Jonas; Moy, Frithjof Emil & Knutsen, Jan Atle [Show all 8 contributors for this article] (2020). Biomassemodell for stortare - Ressursmodell for fremtidens forvaltning. Havforskningsinstituttet. Full text in Research Archive Show summary

  En romlig biomassemodell for stortare er utviklet i et pilotområde med gode data for bunn-, dyp- og miljøforhold og med høy oppløsning. Modellen predikerer en total stortarebiomasse på 457 000 tonn innenfor området. Korrelasjonen mellom modellen og uavhengige data var på hele 0,85 og stemte dermed svært godt overens med virkeligheten. Pilotmodellen er første skritt i utviklingen av en ressursmodell for hele Norge som kan gi forvaltning og næring en oversikt over stortareressursene og legge til rette for bærekraftig høsting av denne rike ressursen.

• Steen, Henning; Norderhaug, Kjell Magnus & Moy, Frithjof Emil (2020). Tareundersøkelser i Nordland i 2019. Havforskningsinstituttet. Full text in Research Archive Show summary

  Havforskningsinstituttet har i perioden 2013-2019 gjennomført undersøkelser i forbindelse med prøvehøsting av stortare (Laminaria hyperborea) på kyststrekningen Sømna (65° 20’ N) – Vega (65° 33’ N) i Nordland. Det ble i 2019 gjennomført oppfølgende undersøkelser av taresamfunnene på felt som ble prøvehøstet i 2013, 2014 og 2017, samt i nærliggende områder som ikke har vært tarehøstet tidligere (referanseområder). I tillegg ble det gjennomført kartlegging av tarevegetasjonen og kråkebolleforekomster i utvalgte breddegradssektorer på kyststrekningen fra Herøy (66° 02’ N) til Bodø (67° 22’ N). Tarevegetasjonen ble undersøkt ved hjelp av undervannsvideo og innsamlinger av tareplanter for studier av morfologi, alder, veksthistorikk, epifytter og kråkebollerekrutter. Undersøkelsene i de tidligere prøvehøstede områdene viser at selv om høstefeltene raskt rekoloniseres av små stortareplanter og tarebiomassen restitueres i løpet av fire år, kreves en hvileperiode på seks år for reetablering av epifyttstruktur og rekruttvegetasjon. Videoobservasjonene viser at tettheten av kråkebolle var lav på de fleste stasjoner undersøkt i Nordland i 2019, og kråkebollebeiting har hatt liten effekt på tarevegetasjonens reetablering i de tidligere prøvehøstede områdene. På kyststrekningen Herøy - Bodø er stortarevegetasjonen best utviklet i ytre, vestlige deler av de undersøkte sektorene. Tettheten av juvenile grønne kråkeboller (Strongylocentrotus droebachiensis) observert i de innsamlede tareplantenes festeorgan (hapter) økte fra sør til nord. Veksthistorikkanalyser av innsamlede tareplanter indikerer at den årlige stilktilveksten er langsommere på kyststrekningen Herøy – Bodø, enn i sørligere områder.

• Naustvoll, Lars Johan; Thormar, Jonas; Lundsør, Elisabeth; Kroglund, Tone; Norderhaug, Kjell Magnus & Moy, Frithjof Emil (2020). ØKOKYST – delprogram Klima. Årsrapport 2019. Miljødirektoratet. Full text in Research Archive Show summary

  ØKOKYST- Økosystemovervåkning i kystvann – har til hensikt å kartlegge, overvåke og rapportere miljøtilstand langs norskekysten i henhold til vannforskriften. Delprogram Klima inkludere områder i Skagerrak og ved Skrova. Basert på biologiske parameter variere tilstanden mellom «svært god» til «moderat» tilstand i 2019. Samlet vurdering basert på støtteparameter gir «god» (II) til «svært dårlig» (V). For flere av vannforekomsten er det kun midlertidig vurdering i 2019.

• Norderhaug, Kjell Magnus; Skjermo, Jorunn; Kolstad, Kari; Broch, Ole Jacob; Ergon, Åshild & Handå, Aleksander [Show all 9 contributors for this article] (2020). Mot en ny havnæring for tare? : Muligheter og utfordringer for dyrking av alger i Norge. Havforskningsinstituttet. Full text in Research Archive Show summary

  Behovet for bærekraftig produksjon av mat fra havet har aktualisert dyrking av tang og tare. Selv om potensialet for dyrking er stort i Norge er produksjonen på prøvestadiet på grunn av utfordringer knyttet til marked, produksjon, miljø og forvaltning. I denne rapporten har Havforskningsinstituttet, SINTEF og NMBU sammen undersøkt mulighetene for utvikling av en bærekraftig ny havnæring og hva som skal til for å lykkes med lønnsom produksjon av alger. Rapporten kommer også med anbefalinger i forhold til å initiere forskning og innovasjon som kan stimulere til utvikling av en lønnsom og bærekraftig taredyrkingsindustri i Norge.

• Naustvoll, Lars Johan; Lundsør, Elisabeth; Thormar, Jonas; Norderhaug, Kjell Magnus; Kroglund, Tone & Moy, Frithjof Emil (2019). ØKOKYST - delprogram Klima. Årsrapport 2018. Miljødirektoratet. Full text in Research Archive Show summary

  ØKOKYST- Økosystemovervåkning i kystvann – har til hensikt å kartlegge, overvåke og rapportere miljøtilstand langs norskekysten i henhold til vannforskriften. Delprogram Klima inkludere områder i Skagerrak og ved Skrova. Basert på biologiske parameter variere tilstanden mellom «svært god» til «dårlig» tilstand i 2018. Samlet vurdering basert på støtteparameter gir «god» tilstand ved begge stasjonene i 2018.

• Gundersen, Hege; Bekkby, Trine; Oug, Eivind; Norderhaug, Kjell Magnus; Fredriksen, Stein & Rinde, Eli (2018). Marin gruntvann. Norsk rødliste for naturtyper 2018. Artsdatabanken. Full text in Research Archive
• Steen, Henning; Norderhaug, Kjell Magnus & Moy, Frithjof Emil (2018). Tareundersøkelser i Nordland i 2018. Havforskningsinstituttet. Full text in Research Archive
• Naustvoll, Lars Johan; Moy, Frithjof Emil; Dolven, Jane Karine Lønne & Norderhaug, Kjell Magnus (2018). ØKOKYST-delprogram Klima. Årsrapport 2017. Miljødirektoratet. Full text in Research Archive Show summary

  ØKOKYST- Økosystemovervåkning i kystvann – har til hensikt å kartlegge, overvåke og rapportere miljøtilstand langs norskekysten i henhold til vannforskriften. Delprogram Klima inkludere områder i Skagerrak og ved Skrova. Basert på biologiske parameter variere tilstanden mellom «svært god» til «dårlig» tilstand I 2017. Samlet vurdering basert på støtteparameter viser at stasjonene variere mellom «svært god» til «svært dårlig» i 2017.

• Steen, Henning; Norderhaug, Kjell Magnus & Moy, Frithjof Emil (2018). Tareundersøkelser i Nordland i 2017. Havforskningsinstituttet. Full text in Research Archive Show summary

  Havforskningsinstituttet har i perioden 2013-2017 gjennomført undersøkelser i forbindelse med prøvehøsting av stortare (Laminaria hyperborea) sør i Nordland. I forkant av prøvehøstingen i 2017 ble tarevegetasjonen undersøkt ved hjelp av undervannsvideo og tareinnsamlinger for studier av morfologi, alder, veksthistorikk og epifytter. Det ble også gjennomført oppfølgende undersøkelser av taresamfunnene på felt som ble prøvehøstet i 2013-2016 og i nærliggende områder som ikke har vært tarehøstet tidligere (referanseområder). Undersøkelsene viste god gjenvekst av stortare på høstefeltene som til nå har vært lite påvirket av beiting fra kråkeboller. Forekomstene av rød kråkebolle (Echinus esculentus) ser imidlertid ut til å ha økt i forhold til tidligere år i den nordligste delen av det undersøkte området på både høstede og ikke-høstede stasjoner. Fire år etter den første prøvehøstingen i 2013 var stortarevegetasjonens størrelses-, alder- og epifyttstruktur, samt tettheten av tarerekrutter i undervegetasjonen, fortsatt ikke tilbake på samme nivå som før høsting. Tarevegetasjonens- og kråkebollebestandenes utvikling i området bør derfor følges videre for å framskaffe et bedre kunnskapsgrunnlag for en framtidig bærekraftig forvaltning av stortareressursene i denne regionen. Fiskeundersøkelser som ble startet før prøvehøsting i 2017 vil bli fulgt opp med nye undersøkelser i 2018 for å teste eventuelle effekter på fisk og skalldyr.

• Hansen, Pia Kupka; Husa, Vivian; Bannister, Raymond; Kutti, Tina; Norderhaug, Kjell Magnus & Naustvoll, Lars Johan [Show all 7 contributors for this article] (2017). Vurdering av egnethet av utslippsindikator for næringssalter og organisk materiale på produksjonsområdenivå. Havforskningsinstituttet. Full text in Research Archive
• Norderhaug, Kjell Magnus; Gundersen, Hege; Høgåsen, Tore; Johnsen, Torbjørn Martin; Severinsen, Gunnar & Vedal, Jens [Show all 8 contributors for this article] (2016). Eutrophication status for Norwegian waters. National report for the third application of OSPARs Common Procedure. Miljødirektoratet. Full text in Research Archive
• Walday, Mats Gunnar; Gundersen, Hege; Gitmark, Janne Kim; Bekkby, Trine; Norderhaug, Kjell Magnus & Pedersen, Are (2015). Videreutvikling av makroalgeindeksene for klassifisering av miljøtilstand i kystvann. Miljødirektoratet. Full text in Research Archive Show summary

  NIVA har i den foreliggende rapport vurdert relevant datatilgang for om indikatorene for nedre voksegrense (MSMDI) og fjæresone (RSLA/RSL) kan videreutvikles til å gjelde flere økoregioner, men også erfaring med de eksisterende indikatorene – fra det praktiske feltarbeid til vurdering av indeksens funksjonalitet. Vi har foreslått og prioritert områder og vanntyper for videreutvikling av de eksisterende indekser. Vi har i tillegg foreslått utvikling av en ny kombinert indeks som både bruker fjæresoneundersøkelser (RSLA) og undersøkelser av nedre voksegrense basert på bruk av droppkamera.

• Norderhaug, Kjell Magnus; Bakke, Torgeir Heggelund; Berge, John A; Fagerli, Camilla With; Tveiten, Lise Ann & Gitmark, Janne Kim [Show all 7 contributors for this article] (2015). Miljøundersøkelser rundt vraket av MS Server. Norsk institutt for vannforskning (NIVA). ISSN 9788257766511. Full text in Research Archive Show summary

  NIVA har gjennomført miljøundersøkelser rundt vraket av MS Server. Resultatene var entydige og hovedkonklusjonen fra undersøkelsene er at vraket av MS Server ikke har negativ påvirkning på miljøet med hensyn på tre viktige undersøkte indikatorer for den marine miljøkvaliteten: biomangfold på hardbunn, miljøgifter i blåskjell og hormonforstyrrelser hos snegl.

• Gundersen, Hege; Norderhaug, Kjell Magnus; Christie, Hartvig C; Moy, Frithjof Emil; Hjermann, Dag Øystein & Vedal, Jens [Show all 9 contributors for this article] (2014). Tallknusing av sukkertaredata. Norsk institutt for vannforskning (NIVA). ISSN 9788257764722. Full text in Research Archive Show summary

  Norsk institutt for vannforskning (NIVA) og Havforskningsinstituttet (HI) har gjennomført prosjektet «Tallknusing av sukkertare-data», på oppdrag fra Miljødirektoratet. Gjennom prosjektet har tilgjengelige data som kan forklare bortfall av sukkertare Saccharina latissima blitt statistisk analysert. Dataserier som er sammenstilt inkluderer datasett fra overvåking (KYS, KYO, ØKOKYST, IO og YO) og forskning (Sukkertareprosjektet og SaccRef) på sukkertare, samt relevante datasett om dens antatte påvirkningsfaktorer (RID, NVE, eKlima, Havforskningsinstituttets hydrografiske målestasjoner, fiskeridata, NAO, samt geofysiske GIS-lag). Analyser viser en generell nedgang i tilstanden av sukkertare på Sør-Vestlandet og Vestlandet, mens Skagerrak i tillegg har opplevd en markant nedgang i indre kystområder med påfølgende oppgang i løpet av 2000-tallet. De viktigste variablene som påvirket sukkertare i denne analysen er flere faktorer som har tilknytning til klimaendringer, tilførsler av næringssalter og partikler og det er sannsynlig at flere faktorer virker sammen. Forekomst av torsk hadde ingen målbar effekt for tilstanden av sukkertare. Selv om forklaringsgraden i analysene var lav var resultatene noenlunde konsistente og gjenspeiler et sett av flere faktorer som kan settes i sammenheng med klimaendringer og næringssalter som de viktigste påvirkningsfaktorene. I rapporten blir det pekt på mulige justeringer i den videre overvåkingen av de store sukkertareforekomstene, og det gis forslag på undersøkelser som kan gjennomføres for å avdekke årsakssammenhenger mellom ulike påvirkningsfaktorer og nedgang i sukkertare i de ulike regionene på Sør- og Vestlandet.

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