Stein Fredriksen

University of Oslo · Department of Biosciences

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...

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 experi...

Brown algae (Phaeophyceae) are habitat‐forming species in coastal ecosystems and include kelp forests and seaweed beds that support a wide diversity of marine life. Host‐associated microbial communities are an integral part of phaeophyte biology, and whereas the bacterial microbial partners have received considerable attention, the microbial eukary...

Hanging gardens - comparing fauna communities in kelp farms and wild kelp forests. https://iss2023.net/2022/08/22/hanging-gardens-do-floating-kelp-farm-communities-resemble-natural-kelp-forests/ Listen to the presentation on YouTube: https://www.youtube.com/watch?v=rhl4qiqncFU

A growing need for food is causing increased interest for seaweed farming globally. This requires the knowledge of the industry’s effects on the marine environment. We therefore aimed to explore the communities hosted by a kelp farm compared to that of wild kelp forests. The study was performed in mid-western Norway. Kelp associated fauna were coll...

Vertebrata lanosa is an intertidal red algal species that grows epiphytically on Ascophyllum nodosum, a brown fucoid alga. V. lanosa received culinary interest in the recent years due to its truffle-like taste and it is currently only harvested from natural populations. This study has focused on the growth of the species in lab cultures and investi...

Introduction Saccharina latissima is a canopy-forming species of brown algae and, as such, is considered an ecosystem engineer. Several populations of this alga are exploited worldwide, and a decrease in the abundance of S. latissima at its southern distributional range limits has been observed. Despite its economic and ecological interest, only a...

Talk at the Annual meeting of the Norwegian Association of Marine Scientists, 22-23.11.2022, Asker, Norway

Saccharina latissima is the most important habitat-forming kelp in sheltered areas of North-Atlantic, and there is also an increasing interest in cultivation and utilization of S. latissima. The cultivation activity may introduce a risk of “crop-to-wild” gene flow from the cultivated crops to natural populations. A baseline study to examine genetic...

We conducted a short-term field sampling complemented with time integrating stable isotope analysis to holistically investigate status and ecological interactions in a remote NE Atlantic Zostera marina meadow. We found high nutrient water concentrations, large biomass of fast-growing, ephemeral macroalgae, low abundance, and biodiversity of epifaun...

Våre undersøkelser i Oslofjorden viser forekomst av flere av de samme fremmede artene som det som er funnet i tidligere undersøkelser. Vi fant både stillehavsøsters, japansk spøkelseskreps, strømgarn, japansk sjølyng, djeveltunge og tøffelnegl. Flest arter og individer ble observert på den innerste stasjonen i indre Oslofjord (Oksval) og på Ula på...

The aim was to acquire knowledge about a selection of marine habitats in the Oslofjord, while also gaining practical experience with the NiN habitat classification system as a tool to meet the needs of management authorities. We also wanted to gain knowledge about changes in habitats previously mapped by the National Program for Mapping Biodiversit...

NIVA og UiO skal på feltarbeid på Søre Sunnmøre i september 2021 (uke 35 og 36). Vi skal da besøke områder med blæretang med ulik grad av fragmentering/flekkvishet, dvs. områder der tangen naturlig er heldekkende («single large»), der vi har mellomstore flekker («several small») or der vi har små flekker («lots of tiny»), se Figur 1, og områder med...

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 miniaturizati...

Coralline red algae in the non-geniculate genera Clathromorphum, Phymatolithon and Lithothamnion are important benthic ecosystem engineers in the photic zone of the Arctic and Subarctic. In these regions, the systematics and biogeography of Clathromorphum and Phymatolithon have mostly been resolved whereas Lithothamnion has not, until now. Seventy-...

Background Brown algae (Phaeophyceae) are essential species in coastal ecosystems where they form kelp forests and seaweed beds that support a wide diversity of marine life. Host- associated microbial communities are an integral part of phaeophyte biology. The bacterial microbial partners of phaeophytes have received far more attention than microbi...

Formålet med prosjektet har vært å skaffe kunnskap om et utvalg marine naturtyper i Oslofjorden, og samtidig skaffe praktisk erfaring med NiN-systemet som verktøy for å dekke miljøforvaltningens behov. Gjennom feltkartlegging har vi skaffet kunnskap om endringer i naturtyper som er kartlagt tidligere i Nasjonalt program for kartlegging av biologisk...

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 s...

The aim was to acquire knowledge about a selection of marine habitats in the Oslofjord, while also gaining practical experience with the NiN habitat classification system as a tool to meet the needs of management authorities. We also wanted to gain knowledge about changes in habitats previously mapped by the National Program for Mapping Biodiversit...

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...

Summary of a large ecological quantitative impact assessment for alien species in Norway. Additional information and data repository: Sandvik H et al (2020) Data from: Ecological impact assessments of alien species in Norway. Dryad Digital Repository, https://doi.org/10.5061/dryad.8sf7m0cjc

1 . Due to globalisation, trade and transport, the spread of alien species is increasing dramatically. Some alien species become ecologically harmful by threatening native biota. This can lead to irreversible changes in local biodiversity and ecosystem functioning, and, ultimately, to biotic homogenisation. 2 . We risk‐assessed all alien plants, a...

The Arctic Ocean is a unique ecosystem hosting a biodiversity that has not yet been elucidated in full detail. There is increasing evidence that there are more kelp species constricted to Arctic/sub‐Arctic habitats hitherto not well investigated, such as Hedophyllum nigripes, which is morphologically very similar to cold‐temperate Laminaria digitat...

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...

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 signi cant and well-known role...

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 r...

We present the results of an inventory and status assessment of alien species in Norway. The inventory covered all known multicellular neobiota, 2496 in total, 1039 of which were classified as naturalised. The latter constitute c. 3% of all species known to be stably reproducing in Norway. These figures are higher than expected from Norway’s latitu...

Abstract In the course of the ongoing global intensification and diversification of human pressures, the study of variation patterns of biological traits along environmental gradients can provide relevant information on the performance of species under shifting conditions. The pronounced salinity gradient, co‐occurrence of multiple stressors, and a...

This study analyses the combined impact of two types of ocean water flow, wave exposure and ocean currents, on kelp Laminaria hyperborea abundance, taking other environmental co-variables into account. The dataset covers many ecoregions along the NE Atlantic (Norwegian) coast, including both the Skagerrak, the North Sea and the Norwegian Sea, from...

Several floristic studies on macroalgae of Svalbard have been published, but as access to the archipelago is difficult, these studies are scattered and often only cover single sites and habitats. Kongsfjorden, Isfjorden and Hornsund are the three most comprehensively investigated areas, and most of the species information comes from these three fjo...

On rocky substrata along shallow water cold-temperate and Arctic coastlines, large brown seaweeds (“kelps”) form structure- and organism-rich habitats of vast ecological significance. The distribution of these ecosystem engineers is largely controlled by the prevailing temperature, light regime and substrate availability, but can also be influenced...

Knowledge of genetic diversity among wild populations is becoming increasingly important as more species are recognized for their bioeconomic value. Industrialization of natural resources, such as kelp in the marine shallow sublittoral zone through cultivation and wild-harvesting, may lead to extensive translocation and local population decimation....

Talk at the Norwegian Association of Marine Scientists annual meeting in Tromsø, Norway.

Talk at the Norwegian Association of Marine Scientists annual meeting in Tromsø, Norway.

Coralline algae form extensive maerl and rhodolith habitats that support a rich biodiversity. Calcium carbonate harvesting as well as trawling activities threatens this ecosystem. Eleven species were recorded so far as maerl-forming in NE Atlantic, but identification based on morphological characters is unreliable. As for most red algae, we now use...

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...

The CoralAlg-project, funded by the Norwegian Biodiversity Information Center, aims at assessing the coralline species diversity of maerl beds along the Norwegian coast. Toward this goal, molecular systematic methods were used along with traditional morphological studies for species identification. Corallines typically show high levels of morpholog...

Sediment cores were collected from an area off the west coast of Norway, where a well-established kelp community made up mainly of Laminaria hyperborea is found. Chemical analyses of the sectioned sediment cores were made, which included organic carbon, carbohydrates and phenols. These were used to collate the sediments in order to establish whethe...

Arctic West Spitsbergen in Svalbard is currently experiencing gradual warming due to climate change showing decreased landfast sea-ice and increased sedimentation. In order to document possible changes in 2012–2014, we partially repeated a quantitative diving study from 1996 to 1998 in the kelp forest at Hansneset, Kongsfjorden, along a depth gradi...

Eelgrass meadows are a common feature in shallow waters along the Norwegian coast, where they provide a habitat for a diverse infaunal community. Recreational boat anchoring and moorings physically scour seagrass and may affect the ecosystem functioning and resilience of the system to natural and anthropogenic disturbances. A small-scale eelgrass (...

A comprehensive expert consultation was conducted in order to assess the status, trends and the most important drivers of change in the abundance and geographical distribution of kelp forests in European waters. This consultation included an on-line questionnaire, results from a workshop and data provided by a selected group of experts working on k...

Benthic algal vegetation was investigated at 10 sites in Isfjorden, Svalbard. Five sites were visited during summer 2010 and five during summer 2012. Both the littoral and sublittoral vegetation were sampled, the littoral by hand-picking and use of a throwable rake and the sublittoral using a triangular dredge. A total of 88 different taxa were reg...

Supplementary files to doi.org/10.3402/polar.v34.25994

Nutrient pollution and reduced grazing each can stimulate algal blooms as shown by numerous experiments. But because experiments rarely incorporate natural variation in environmental factors and biodiversity, conditions determining the relative strength of bottom-up and top-down forcing remain unresolved. We factorially added nutrients and reduced...

A northward trend of declining abundance of sea urchins (Strongylocentrotus droebachiensis) and increasing kelp recovery along the coast of Norway has provided an opportunity to explore whether the decline of sea urchins can be explained by systematic variations in demographic or fitness-related traits. The population density of sea urchins in mid-...

The stipes of older Laminaria hyperborea individuals are heavily covered by epiphytic assemblages that are dominated by macroalgae, and we hypothesized that the production of these algae may contribute significantly to total primary production of the kelp forest ecosystem. The epiphytic assemblages on the stipes of Laminaria were dominated by poten...

This paper focuses on the marine foundation eelgrass species, Zostera marina , along a gradient from the northern Baltic Sea to the north‐east Atlantic. This vast region supports a minimum of 1480 km ² eelgrass (maximum >2100 km ² ), which corresponds to more than four times the previously quantified area of eelgrass in Western Europe. Eelgrass mea...

We did a survey on macroalgal diversity along a transect off Hansneset (78°39′N, 11°57′E), Kongsfjorden, western Svalbard, between 0- and >15-m depths in 2012/2013. One major intention was to compare our data to a similar study performed in 1996/1998 at the same site and to document possible changes. We identified 58 spe- cies of macroalgae, 12 Chl...

In central Norway, populations of the green sea urchin Strongylocentrotus droebachiensis are collapsing, but the factors controlling its population density have not yet been elucidated. Through field sampling, we identified several sea urchin predators and investigated their predation rates on recently settled S. droebachiensis in laboratory experi...

During the growth season of February to May, a release of stored nitrate into the sea water medium was observed in a night and day incubation of 2-3 year old plants of Laminaria hyperborean A large part of the released nitrate appears to be assimilated by photosynthesis during the day. This is at variance with the common consensus that stored nitra...

Supporting info item

Background/Question/Methods Ecosystem processes are mediated by interactions between resource supply, consumer pressure, and community composition, with the balance shifting along environmental gradients. A frontier in basic and applied ecology is understanding how these multifarious processes interact, and organizing the complexity into predicti...

Background/Question/Methods Two fundamental, and related, challenges to prediction in ecology are complexity and idiosyncrasy. How do we evaluate the importance of multiple, interacting factors in mediating ecological structure and processes? And how do we assess whether the results are general? One promising way forward is the comparative-experi...

Patterns of potential recruitment, survival, age-structure, density, biomass and primary production were stud