Janne E. Søreide

University Centre in Svalbard | UNIS · Department of Arctic Biology

The European Arctic, which includes the Svalbard archipelago, is situated in one of the areas showing most notable changes due to global warming and associated cascade events and processes. The main driving factor, temperature rise, is continuing to cause a large-scale overall decline in ice, from glacier retreating, less coastal land-fast ice to t...

Benthic organisms typically possess a planktonic propagule stage in the form of larvae or spores, which enables them to spread over large distances before settlement, and promotes tight pelago-benthic coupling. However, factors driving dispersal and epibenthos recruitment in shallow hard-bottom Arctic communities are poorly known. We therefore cond...

Sea-ice microalgae are a key source of energy and nutrient supply to polar marine food webs, particularly during spring, prior to open-water phytoplankton blooms. The nutritional quality of microalgae as a food source depends on their biomolecular (lipid:protein:carbohydrate) composition. In this study, we used synchrotron-based Fourier transform i...

The Arctic polar nights bring extreme environmental conditions characterised by cold and darkness, which challenge the survival of organisms in the Arctic. Additionally, multiple anthropogenic stressors can amplify the pressure on the fragile Arctic ecosystems during this period. Determining how multiple anthropogenic stressors may affect the survi...

Recent research highlighted significant marine biological activity during the Arctic winter, with poorly known implications for the biological carbon pump. We used moored instruments to (1) track the development of the pelagic food web of a high‐Arctic marine ecosystem from winter to spring, and (2) assess the role of zooplankton‐mediated processes...

Arctic sea-ice diatoms fuel polar marine food webs as they emerge from winter darkness into Spring. Through their photosynthetic activity they manufacture the nutrients and energy that underpin secondary production. Sea-ice diatom abundance and biomolecular composition vary in space and time. With climate change causing short-term extremes and long...

Sea ice algae have a broad salinity tolerance but can experience stress during rapid decreases in salinity that occur with seasonal ice melt and during ice sample melt. This study investigated the impact of salinity on the photophysiological responses of bottom-ice algal communities from two Svalbard fjords (Tempelfjorden and Van Mijenfjorden). To...

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...

This study compares the active and resting metabolic rates of species and life stages of copepods during the Arctic winter. Measurements were taken on individuals, and rates were described as functions of body mass. Differences in metabolic rate between species and life stages with the same mass were taken as evidence of distinct lifestyles. Copepo...

Svalbard is one of the fastest warming regions in the Arctic including massive loss in fjord sea ice both in terms of area coverage, ice thickness and duration. Sea ice is a habitat for a wide variety of microscopic flora and fauna, and we know little about the impact of accelerated loss of sea ice on this unique sea ice community. Here, we present...

Tourism has been booming in Svalbard and has almost returned to pre-pandemic levels. At the same time, the island is a hotspot of rapid and cascading climate and environmental changes, which are already placing natural and social systems under stress. There is more precipitation, less sea ice, and glaciers are shrinking at an increasing rate. Prese...

Kelps are a dominant macrophyte group and primary producer in Arctic nearshore waters that provide significant services to the coastal ecosystem. The quantification of these services in the Arctic is constrained, however, by limited estimates of kelp depth extent, which creates uncertainties in the area covered by kelp. Here, we test the environmen...

Climate-driven alterations of the marine environment are most rapid in Arctic and subarctic regions, including Hudson Bay in northern Canada, where declining sea ice, warming surface waters and ocean acidification are occurring at alarming rates. These changes are altering primary production patterns that will ultimately cascade up through the food...

Although studies of the Arctic region have a long history there are still many aspects that require research. Benthic species are important in the studies of environmental impact. However, there is currently very little understanding of what factors drive the process of benthic larval recruitment and assemblage development. This field study, conduc...

The Nansen Legacy Polar Cod Connectivity cruise aimed at unravelling polar cod and capelin population connectivity and relation to the physical and chemical environment in Svalbard’s fjords. The main focus areas were Isfjorden, Kongsfjorden, Storfjorden and the South-East of Svalbard. A total of 36 stations were visited to collect of information on...

Fjord systems are transition zones between land and sea, resulting in complex and dynamic environments. They are of particular interest in the Arctic as they harbour ecosystems inhabited by a rich range of species and provide many societal benefits. The key drivers of change in the European Arctic (i.e., Greenland, Svalbard, and Northern Norway) fj...

The high Arctic Svalbard tidal flat ecosystem is impacted by global warming, which could allow invasion by additional species with changes in the environment supporting their growth. The transport of additional species to Svalbard could be aided by an increase in the numbers of people traveling there. Anthropogenic activities related with global wa...

A warmer Arctic with less sea ice will likely improve macroalgae growth conditions, but observational data to support this hypothesis are scarce. In this study, we combined hydroacoustic and video inspections to compare the depth of growth, density and thickness of macroalgae (>10 cm) meadows in two contrasting climate regimes in Svalbard 1) the wa...

This cruise was the second of in total four seasonal cruises with RV Kronprins Haakon in 2019/20 focusing on biology in the project Arven etter Nansen (AeN). This seasonal cruise was named Q4 (Q4= 4th quarter of the year) investigating in total 17 stations of the established AeN transect along 34 E in the Northern Barents Sea and adjacent Arctic Ba...

Climate change has affected the Arctic Ocean (AO) and its marginal seas significantly. The reduction of sea ice in the Arctic region has altered the magnitude of photosynthetically available radiation (PAR) entering the water column, impacting primary productivity. Increasing cloudiness in the atmosphere and rising turbidity in the coastal waters o...

The Nansen Legacy (NL) JC3 cruise (19.02.-11.03.2022) aimed to fill regional, temporal and scientific gaps following the earlier NL cruises, in particular during the winter-to-spring transition and in the northern part of the NL transect to the Nansen Basin. Joint physical, chemical, and biological sampling and experiments for new technology addres...

Seasonal patterns in mesozooplankton composition, vertical distribution, and timing of reproduction are challenging to study in the open sea due to ocean currents and mix of populations of different origins. Sill fjords, on the other hand, with restricted water exchange, are ideal locations for studying taxa- and community-specific adaptations to t...

Arctic coasts, which feature land-ocean transport of freshwater, sediments, and other terrestrial material, are impacted by climate change, including increased temperatures, melting glaciers, changes in precipitation and runoff. These trends are assumed to affect productivity in fjordic estuaries. However, the spatial extent and temporal variation...

In the Arctic shelf seas, the mesozooplankton biomass is dominated by the arctic copepod Calanus glacialis, but its boreal congeneric C. finmarchicus is expanding northwards. Even though it is already there, C. finmarchicus may not be able to truly establish itself in the Arctic seas and potentially replace C. glacialis. We compared metabolic and d...

The calanoid copepod Calanus glacialis dominates the mesozooplankton biomass in the Arctic shelf seas, but its smaller North Atlantic sibling Calanus finmarchicus is expanding northwards and may potentially replace it if the climate continues to warm. Here we studied the population structure, overwintering strategies, gonad maturation and egg produ...

Climate change-driven increases in air and sea temperatures are rapidly thawing the Arctic cryosphere with potential for remobilization and accumulation of legacy persistent organic pollutants (POPs) in adjacent coastal food webs. Here, we present concentrations of selected POPs in zooplankton (spatially and seasonally), as well as zoobenthos and s...

The Arctic is greatly impacted by climate change. The increase in air temperature drives the thawing of permafrost and an increase in coastal erosion and river discharge. This leads to a greater input of sediment and organic matter into coastal waters, which substantially impacts the ecosystems by reducing light transmission through the water colum...

The Arctic is greatly impacted by climate change. The increase in air temperature drives the thawing of permafrost and an increase in coastal erosion and river discharge. This leads to a greater input of sediment and organic matter into coastal waters, which substantially impacts the ecosystems by reducing light transmission through the water colum...

Rapidly warming Arctic is facing significant shifts in the zooplankton size-spectra manifested as increasing numbers of the small-sized copepod Oithona similis. Here we present a unique continuous data set covering 22 months, on its copepodite structure along with environmental drivers in the Atlantic-influenced high Arctic fjord Isfjorden (Spitsbe...

The thecosome pteropods Limacina helicina and L. retroversa are important contributors to the zooplankton community in high-latitude environments but little is known about their distribution and life cycle under polar conditions. We collected the early life stages (< 1 mm) of the thecosome population in 2012 and 2013 at a bi-weekly to monthly resol...

The impact of the rapidly changing Arctic on zooplankton community structure and seasonal behaviour is not yet understood. Here we examine 6 months of under-ice zooplankton observations from the N-ICE2015 expedition (January to June 2015) in the Nansen Basin and on the Yermak Plateau north of Svalbard. Stratified sampling in the water column was do...

Recent observations from high-latitude marine ecosystems indicate that non-consumptive mortality may be particularly high in Arctic zooplankton during the polar night. Here we have estimated the contribution of dead organisms to the mesozooplankton community in the high Arctic (Svalbard 78–81oN) during the polar night (January), in spring (May) and...

Understanding the diversity and functioning of Arctic sea ice ecosystems is vital to evaluate and predict the impact of current and future climate change. In the microscopic communities inhabiting the brine channels inside sea ice, nematodes often dominate numerically and act as bacterivores and herbivores. Despite nematodes great abundances and kn...

In high Arctic fjords, riverine inputs of freshwater and terrestrial particles give rise to turbid plumes in the nearshore zone during melt season and thus act as a major impediment to light availability and primary productivity within the water column. However, the remoteness of Arctic fjords limits our understanding of key drivers of these plumes...

Small copepods are the most diverse and numerous group in high-latitude zooplankton, yet our knowledge of important species remains poor because of the difficulties involved in correct species identification. In this study, we use a molecular method of identification, a species-specific polymerase chain reaction, to provide the first description of...

The marine pelagic primary production is an important energy source for most Arctic ecosystems, both marine and terrestrial. Single‐celled algae in the water column and in sea ice are at the base of the food web. There are two main drift patterns for sea ice and the upper polar mixed layer in the Arctic Ocean: the Beaufort Gyre (BG) and the Transpo...

Coastal waters are among the most productive regions in the Arctic (Leu et al. 2015; Smola et al. 2017; Ardyna et al. 2020). In these areas, a strong coupling exists between the sea and the land, and the shallow depths create a tight pelagic-benthic coupling (McGovern et al. 2020). These regions are also critical breeding and foraging grounds for m...

Meroplankton comprise mainly of pelagic larvae of benthic invertebrates and play an important role as consumers and prey in coastal ecosystems. During a year-round study in Isfjorden (Svalbard Archipelago; >78°N), two locations (stations North and South) were sampled every third month to capture seasonal dynamics of meroplankton at high-latitudes,...

In the North Atlantic and the Arctic Ocean, four species of the copepod genus Calanus dominate the zoo-plankton biomass. Because of their morphological resemblance, knowledge of their respective distribution range has long been biased by misidentification, until the recent use of molecular tools uncovered numerous areas of sympatry. As hybridizatio...

Climate-change driven increases in temperature and precipitation are leading to increased discharge of freshwater and terrestrial material to Arctic coastal ecosystems. These inputs bring sediments, nutrients and organic matter (OM) across the land-ocean interface with a range of implications for coastal ecosystems and biogeochemical cycling. To in...

Isfjorden, a broad Arctic fjord in western Spitsbergen, has shown significant changes in hydrography and inflow of Atlantic Water (AW) the last decades that only recently have been observed in the Arctic Ocean north of Svalbard. Variability and trends in this fjord’s climate and circulation are therefore analysed from observational and reanalysis d...

Satellite remote sensing offers a unique opportunity to gain insight into seasonally and spatially dynamic processes in Arctic coastal ecosystems. It can be used to estimate key water quality parameters, including suspended particulate matter (SPM) concentration with a higher temporal resolution and synoptic coverage. The present study aims to...

Pelagic communities play a key role in Arctic ecosystems. Although zooplankton occupy several different trophic levels in the food chain, their primary niche is often considered that of a link between pelagic and ice-associated primary production on one side and higher trophic levels on the other. In fact, most of the biological energy (organic car...

Calanus is one of the best studied genera of Arctic zooplankton, but still we know very little about the males since they are short-lived and mainly present in winter. Their short lifespan compared to females is assumed to be a combination of high mating activity, no feeding and consequential depletion of lipid stores. In this study we tested 1) if...

Pelagic larvae of benthic organisms comprise a substantial part of the coastal Arctic zooplankton community in spring–summer. We studied the timing, growth, and pelagic duration of Cirripedia larvae in Adventfjorden, a high-Arctic fjord in Spitsbergen, Svalbard. Two distinct abundance peaks were found: one in early May (~ 25.000 ind. m−3) and anoth...

Adult males of Calanus copepods in the Arctic are mainly observed between late autumn and late spring, and are seldom recorded during summer. Due to logistical constraints, there are still relatively few studies on zooplankton in high-latitude regions during the winter, and subsequently, little is known about Calanus males. Here, we present data on...

The theory of life‐history evolution investigates how growth‐reproduction trade‐offs drive evolution of body size in uni‐ and multivoltine (one or more generations per year) arthropods. Existing theory does not predict how the length of the feeding season (season length hereafter) affects body size in semivoltine (i.e., juvenile period longer than...

Recruitment process is one of the first steps of community development and has a substantial consequence for population dynamics and structure. The main aim of the project was to investigate seasonal variability of larvae recruitment in the Arctic fjord-Isfjorden (West Spitsbergen) in relation to location (two sites under the influence of Atlantic...

Barnacles (Crustacea: Cirripedia) are an important group of organisms in marine ecosystems, but they are also meaningful from the human perspective. They have big potential for biofouling, which is a significant vector for transferring invasive species. Furthermore, spreading over large distances and colonization of new territories is possible due...

Arctic marine ecosystems support fisheries of significant and increasing economic and nutritional value. Commercial stocks are sustained by pelagic food webs with relatively few keystone taxa mediating energy transfer to higher trophic levels, and it remains largely unknown how these taxa will be affected by changing climate and the influx of borea...