Bodil Bluhm

• PhD
• Professor at UiT The Arctic University of Norway

The longevity (lifespan) and growth rates of a given species provide the basis for estimating its contributions to secondary production and energy flow in an ecosystem, for guiding management decisions, and determining recovery times after disturbances. For brittle stars, a class of echinoderms that dominate the megabenthos in various marine system...

Marine nematodes dominate the meiofauna of benthic sediments, but few studies have investigated their trophic roles. We studied the eukaryote diet composition of nematodes from surface sediments on the Arctic Barents Sea shelf, shelf break and adjacent Nansen Basin, during four seasons, using prey metabarcoding of the 18S ribosomal RNA gene. Monhys...

The projected transition of the central Arctic Ocean (CAO) into a warmer, seasonally ice-free ocean requires more knowledge of this environment to predict changes in the structure and dynamics of its ecosystems. We aimed to compare the state and underlying processes of Nansen Basin and Amundsen Basin ecosystems observed in August–September 2021 and...

The Kitikmeot Sea, in the south-central Canadian Arctic Archipelago, is an estuarine system comprised of Coronation Gulf, Bathurst Inlet, Dease Strait, and Queen Maud Gulf. It is unique in the pan-Arctic system due to three defining features: (1) shallow bounding straits to the west (Dolphin and Union Strait) and northeast (Victoria Strait) that ar...

Climate change is challenging species’ abilities to respond and function. In the Arctic, shifts in temperature and ice cover are disrupting established biological interactions and thereby ecosystem structure and function. By examining epibenthic communities in coastal and continental shelf habitats of Northeast Greenland that have been ice-locked f...

Climate change is rapidly modifying biodiversity across the Arctic, driving a shift from Arctic to more boreal ecosystem characteristics. This phenomenon, known as borealization, is mainly described for certain functional groups along sub-Arctic inflow shelves (Barents and Chukchi Seas). In this review, we evaluate the spatial extent of such altera...

Benthic (seafloor) remineralization of organic material determines the fate of carbon in the ocean and its sequestration. Bottom water temperature and labile carbon supply to the seafloor are expected to increase in a warming Arctic and correspondingly, benthic remineralization rates. We provide some of the first experimental data on the response o...

Interest in the deep Arctic Ocean is rapidly increasing from governments, policy makers, industry, researchers, and conservation groups, accentuated by the growing accessibility of this remote region by surface vessel traffic. In this review, our goal is to provide an updated taxonomic inventory of benthic taxa known to occur in the deep Arctic Oce...

Objectives Small copepods (<2 mm) compose an important constituent of the Arctic marine food web, but their trophic interactions remain largely unexplored, partly due to methodological limitations. Methods We here characterize the prey of the abundant cyclopoid Oithona similis, harpacticoid Microsetella norvegica and calanoid Microcalanus spp. fro...

Marine invertebrate habitats are experiencing warming, and oceanic carbon dioxide levels are on the rise. These changes result in shifts in species distributions. Monitoring and understanding these shifts provides vital information because each species plays a unique ecological role, and the human utilization of marine species is intrinsically link...

The polymer-facilitated flux of ice algae on Arctic shelves can initiate benthic activity and growth after the nutritionally constrained winter period. Lipid-rich ice algae are readily consumed by benthos and those entering the sediment can benefit deposit feeders. Ice algae assimilated by benthic organisms cascade up multiple trophic levels within...

On Arctic shelves, benthic food-webs are tightly linked to overlying primary production. In the seasonal ice zone, sympagic (ice-associated) primary production can be a major source of carbon for the benthos on productive inflow shelves. However, the role of sympagic organic matter is less well-understood in food webs of heavily ice-covered, less-...

Forestalling the decline of global biodiversity requires urgent and transformative action at all levels of government and society, particularly in the Arctic Ocean and adjacent seas where rapid changes are already underway. Amid growing scientific support and mounting pressure, the majority of nations have committed to the most ambitious conservati...

The Barents Sea is one of the Polar regions where current climate and ecosystem change is most pronounced. Here we review the current state of knowledge of the physical, chemical and biological systems in the Barents Sea. Physical conditions in this area are characterized by large seasonal contrasts between partial sea-ice cover in winter and sprin...

The rapid decline of Arctic sea ice makes understanding sympagic (ice-associated) biology a particularly urgent task. Here we studied the poorly known seasonality of sea-ice protist and meiofauna community composition, abundance and biomass in the bottom 30 cm of sea ice in relation to ice properties and ice drift trajectories in the northwestern B...

During the productive polar day, zooplankton and sea-ice amphipods fulfill a critical role in energy transfer from primary producers to higher trophic-level species in Arctic marine ecosystems. Recent polar night studies on zooplankton and sea-ice amphipods suggest higher levels of biological activity than previously assumed. However, it is unknown...

Amid the alarming atmospheric and oceanic warming rates taking place in the Arctic, western fjords around the Svalbard archipelago are experiencing an increased frequency of warm water intrusions in recent decades, causing ecological shifts in their ecosystems. However, hardly anything is known about their potential impacts on the until recently co...

Pelagic–benthic coupling describes the connection between surface-water production and seafloor habitats via energy, nutrient and mass exchange. Massive ice loss and warming in the poorly studied Arctic Chukchi Borderland are hypothesized to affect this coupling. The strength of pelagic–benthic coupling was compared between 2 years varying in clima...

Polar cod (Boreogadus saida) is an important trophic link within Arctic marine food webs and is likely to experience diet shifts in response to climate change. One important tool for assessing organism diet is bulk stable isotope analysis. However, key parameters necessary for interpreting the temporal context of stable isotope values are lacking,...

This dataset contains the Latin names and literature-based broad trophic and feeding occurrence (in terms of category of feeding depth zone) characteristics of 809 taxa recorded in the Barents Sea during scientific surveys by the Institute of Marine Research (IMR, Havforskningsinstituttet), Norway during the summers of 2014, 2015, and 2016. Trophic...

The rapid ongoing changes in the Central Arctic Ocean call for baseline information on the pelagic fauna. However, sampling for motile organisms which easily escape vertically towed nets is challenging. Here, we report the species composition and catch weight of pelagic fishes and larger zooplankton from 12 trawl hauls conducted in ice covered wate...

Trait-based approaches connect the traits of species to ecosystem functions to estimate the functional diversity of communities and how they may respond to environmental change. For the first time, we compiled a traits matrix across 11 traits for 28 species of Arctic ice meiofauna, including Copepoda (Subclass), Nematoda (Phylum), Acoela (Order), R...

On Arctic shelves, where primary production occurs in both the pelagic and sympagic (ice-associated) habitats, sympagic organic material (OM) can constitute a disproportionate fraction of benthic diets due to higher sinking rates and lower grazing pressure than pelagic OM. Less documented is how sympagic OM assimilation across feeding guilds varies...

Many benthic invertebrate taxa possess planktonic early life stages which drift with water currents and contribute to dispersal of the species, sometimes reaching areas beyond the current ranges of the adults. Until recently, it had been difficult to identify planktonic larvae to species level due to lack of distinguishing features, preventing dete...

Benthic communities below the photic zone are largely reliant on the export of surface-water primary production and the flux of partially degraded organic matter to the seabed, i.e. pelagic−benthic coupling. Over the past decades, however, the role of chemosynthetically produced carbon in food webs has been recognized in various habitats. Cold seep...

Ecosystem description of the Central Arctic Sea

In the Arctic, sea ice loss has already transformed the dominant sources and periodicity of primary production in some areas, raising concerns over climate change impacts on benthic communities. Considered to be excellent indicators of environmental changes, benthic invertebrates play important roles in nutrient cycling, sediment oxygenation and de...

Kelps play important roles in ecosystems as they provide structural habitat and protection, and supply food. Given these beneficial roles and observed increases in seaweed biomass and distribution ranges across the Arctic, mapping kelp occurrence around Arctic coasts is both timely and necessary for future conservation. Here, we fill spatial gaps i...

The main scientific goal of the Nansen Legacy JC2-2 cruise was to extend the project’s research activities from the northern Barents Sea shelf into the central Arctic Ocean. Specifically, JC2-2 addressed objectives of the research foci RF1, RF2 and RF3 by jointly collecting interdisciplinary samples and data at five process (P) and in-between NLEG...

While numerous regional studies of bathymetric zonation of benthic fauna globally have been done, few large-scale analyses exist, and no ocean-scale studies have focused on the Arctic Ocean to date. In the present work we, hence, examined bathymetric zonation of macro- and megabenthos over a depth range spanning from the shelf to the abyssal plain...

The Nansen Legacy Q3 cruise, 5-27 August 2019, initiated the seasonal investigations of the Nansen Legacy transect. The transect represent an environmental gradient going through the northern Barents Sea, and included 7 process stations (P1-P7) lasting 6-53 hrs. CTD stations were taken to increase the hydrographic resolution on the transect. The pr...

Arctic sea ice contains a substantial amount of living biota of which part is lost through melt and export out of the Arctic Ocean every year. It is unclear how populations can be maintained within the Arctic Ocean. A representative ice inhabitant, the amphipod Apherusa glacialis was previously assumed to spend its entire life in the sea ice habita...

Increasing ice melting in the Arctic circle is predicted to open many sea- and land-use opportunities, but these will impose additional threats and challenges to the already changing Arctic ecosystems and biodiversity as well as the livelihoods of local communities. This Voices asks: how can we anticipate and manage sea-/land-use impacts in the Arc...

Community assembly theory states that species assemble non-randomly as a result of dispersal limitation, biotic interactions, and environmental filtering. Strong environmental filtering likely leads to local assemblages that are similar in their functional trait composition (high trait convergence) while functional trait composition will be less si...

The sustainable development and environmental protection of the Arctic ecosystem is on the agenda globally. The Convention of Biological Diversity (CBD) and the UN Sustainable Development Goals call for conserving at least 10 per cent of coastal and marine areas globally. Management tools to achieve this goal include marine protected areas (MPAs) a...

Sea-ice macrofauna includes ice amphipods and benthic amphipods, as well as mysids. Amphipods are important components of the sympagic food web, which is fuelled by the production of ice algae. Data on the diversity of sea-ice biota have been collected as a part of scientific expeditions over decades, and here we present a pan-Arctic analysis of da...

The Svalbard region faces drastic environmental changes, including sea-ice loss and “Atlantification” of Arctic waters, caused primarily by climate warming. These changes result in shifts in the sea-ice-associated (sympagic) community structure, with consequences for the sympagic food web and carbon cycling. To evaluate the role of sympagic biota a...

Sea-ice declines in the European Arctic have led to substantial changes in marine food webs. To better understand the biological implications of these changes, we quantified the contributions of ice-associated and pelagic carbon sources to the diets of Arctic harp and ringed seals using compound-specific stable isotope ratios of fatty acids in spec...

To reach the goal of large-scale seaweed cultivation in Norway and the rest of Europe, new knowledge about the commercially important kelp species Saccharina latissima is needed. Efforts to maximise biomass by outplanting the seaweed in different seasons can affect seaweed quality. Here, we investigate the effects of outplanting time (February, Apr...

In many species of marine benthic invertebrates, a planktonic larval phase plays a critical role in dispersal. Very little is known about the larval biology of most species, however, in part because species identification has historically been hindered by the microscopic size and morphological similarity among related taxa. This study aimed to dete...

Assessment of Arctic deep-sea ecosystem functioning is currently an urgent task considering that ongoing sea-ice reduction opens opportunities for resource exploitation of yet understudied deep-sea regions. We used Biological Trait Analysis to evaluate ecosystem functioning and test if common paradigms for deep-sea fauna apply to benthic epifauna o...

Oil production in Arctic ice-covered areas poses a risk for pollution of the ecosystem including that within the brine channel network of sea ice. Sea-ice autotrophs contribute substantially to Arctic primary production, but are inherently difficult to test for oil exposure responses in situ. This study had two objectives, first, we developed a sui...

Joint Cruise 1-2 with R/V Kronprins Haakon addressed objectives of RF1, RF2 and RF3 on the Nansen Legacy main transect in open water and within the sea ice. The focus was on comparing the state of the physical, chemical and biological conditions in the southern and northern parts of the study area. Given this was the first research cruise on the ve...

Continental slopes – steep regions between the shelf break and abyssal ocean – play key roles in the climatology and ecology of the Arctic Ocean. Here, through review and synthesis, we find that the narrow slope regions contribute to ecosystem functioning disproportionately to the size of the habitat area (∼6% of total Arctic Ocean area). Driven by...

The Arctic Ocean is overwhelmingly forced by its lateral boundaries, and interacts with, the global system. For the development of nested conceptual models of the Arctic Ocean ecosystem we here choose the full pan-Arctic as our focal scale. Understanding the pan-Arctic scale, however, requires that we look at the underlying scales of its major comp...

The marine area of Northeast Greenland belongs to the largest national park in the world. Biodiversity assessments and tailored conservation measures often target specific physiographic or oceanographic features of an area for which detailed knowledge on their biological communities is incomplete. This study, therefore, characterizes epibenthic meg...

Alaskan Arctic shelf communities are currently experiencing dramatic changes that will likely affect ecosystem functioning of Arctic marine benthic communities. Here, functional diversity based on biological traits was used to assess differences and similarities in ecosystem functioning between 2 shelf systems that are geographically close but vary...

The Working Group on the Integrated Assessment of the Central Arctic Ocean (WGICA) aims to provide a holistic analysis of the present and future status of the ecosystem and human activities therein. Data collection in the Central Arctic Ocean (CAO) has been inconsistent both spatially and temporally, which can limit the ability to conduct comprehen...

Climate warming influences structure and function of Arctic benthic ecosystems. Assessing the response of these systems to perturbations requires long-term studies addressing key ecological processes related to recolonization and succession of species. Based on unique time-series (1980–2017), this study addresses successional patterns of hard-botto...

The Norwegian coastline covers more than 10° in latitude and provides a range in abiotic and biotic conditions for seaweed farming. In this study, we compared the effects of cultivation depth and season on the increase in biomass (frond length and biomass yield), chemical composition (protein, tissue nitrogen, intracellular nitrate and ash content)...

An important yet still not well documented aspect of recent changes in the Arctic Ocean is associated with the advection of anomalous sub-Arctic Atlantic- and Pacific-origin waters and biota into the polar basins, a process which we refer to as borealization. Using a 37-year archive of observations (1981–2017) we demonstrate dramatically contrastin...

A strong decline and thinning of the Arctic sea-ice cover over the past five decades has been documented. The former multiyear sea-ice system has largely changed to an annual system and with it the dynamics of sea-ice transport across the Arctic Ocean. Less sea ice is reaching the Fram Strait and more ice and ice-transported material is released in...

The large declines in Arctic sea-ice age and extent over the last decades could have altered the diversity of sea-ice associated unicellular eukaryotes (referred to as sea-ice protists). A time series from the Russian ice-drift stations from the 1980s to the 2010s revealed changes in community composition and diversity of sea-ice protists from the...

Half of the Arctic Ocean is deep sea (>1000 m), and this area is currently transitioning from being permanently ice-covered to being seasonally ice-free. Despite these drastic changes, it remains unclear how organisms are distributed in the deep Arctic basins, and particularly what feeds them. Here, we summarize data on auto-and heterotrophic organ...

Benthic communities change drastically in both biomass and community structure with increasing water depth on a global scale, attributed to a combination of food supply, environmental drivers, as well as physiological and competitive capacities. In the Arctic, benthic biogeographic patterns are additionally thought to be a result of the region’s gl...

Apherusa glacialis is a common, sea ice-associated amphipod found throughout the Arctic Ocean and has long been considered permanently associated with the sea ice habitat. However, pelagic occurrences of A. glacialis have also been reported. It was recently suggested that A. glacialis overwinters at depth within the Atlantic-water inflow near Svalb...

In the Arctic, sea ice loss has already transformed the dominant sources and periodicity of primary production in some areas, raising concerns over impacts of climate change on benthic communities. Benthic invertebrates play important roles in nutrient cycling, sediment oxygenation and decomposition and are very good indicators of changes. Neverthe...

The red king crab Paralithodes camtschaticus (Tilesius, 1815) is a large predator intentionally introduced to the Barents Sea and adjacent fjords in the 1960s. Its establishment has given rise to both a high-value fishery and destructive effects on seafloor habitats and communities. Given the need for accurate information on age, growth, and longev...

The red king crab Paralithodes camtschaticus (Tilesius, 1815) is a large predator intentionally introduced to the Barents Sea and adjacent fjords in the 1960s. Its establishment has given rise to both a high-value fishery and destructive effects on seafloor habitats and communities. Given the need for accurate information on age, growth, and longev...

Pelagic larval stages (meroplankton) of benthic invertebrates seasonally make up a significant proportion of planktonic communities, as well as determine the distribution of their benthic adult stages, yet are frequently overlooked by both plankton and benthic studies. Within the Arctic, the role of meroplanktonic larvae may be particularly importa...

The snow crab Chionoecetes opilioFabricius, 1788 is a newly established species in the Barents Sea. Since the first individuals were recorded in 1996, the population has increased and a fishery was initiated in 2012. Mature female snow crab caught in the central Barents Sea were investigated with regards to fecundity. Ovigerous females (N = 185) ra...

Epifaunal communities from the poorly studied Arctic deep sea of the Chukchi Borderland region were investigated to: (1) determine differences in community structure among ridges, plateau with pockmarks, and much deeper basins as three main habitat types, (2) analyse the environmental factors that might shape these communities, and (3) investigate...

In light of ongoing, and accelerating, environmental changes in the Pacific sector of the Arctic Ocean, the ability to track subsequent changes over time in various marine ecosystem components has become a major research goal. The high logistical efforts and costs associated with arctic work demand the prudent use of existing resources for the most...

Polar marine regions are facing rapid changes induced by climate change, with consequences for local faunal populations, but also for overall ecosystem functioning, goods and services. Yet given the complexity of polar marine ecosystems, predicting the mode, direction and extent of these consequences remains challenging. Trait-based approaches are...

This supplement presents image sources as one example to help overcome lack of trait data in polar (and other) areas. Pros and cons are discussed.

This supplement explains how the 323 (standardized) traits found via our literature survey of 233 marine trait-based studies where grouped into 20 topical clusters (see Supplement 1: Degen EcolIndApp1 2018). Based on these 20 clusters the Table 2 in the main text was constructed.