Pieńkowski AJ*¹², Husum K³, Belt ST⁴, Ninnemann U⁵, Köseoğlu D⁵, Divine DV³, Smik L⁴, Knies J⁶⁷, Hogan K⁸, Noormets R²
¹Adam Mickiewicz University, Poznań, Poland, ²The University Centre in Svalbard (UNIS), Longyearbyen, Svalbard, Norway, ³Norwegian Polar Institute, Tromsø, Norway, ⁴University of Plymouth, Plymouth, UK, ⁵University of Bergen, Bergen, Norway, ⁶Geological Survey of Norway, Trondheim, Norway, ⁷UiT The Arctic University of Norway, Tromsø, Norway, ⁸British Antarctic Survey, Cambridge, UK
While climate model simulations provide valuable insight into potential future Arctic sea-ice scenarios, marine geological archives offer key information on how sea ice responded to substantial climatic warming in the past, particularly during periods characterized by warmer-than-present conditions. The HTM (Holocene Thermal Maximum), ~10.0-6.0 cal ka BP, was the last major period of warm climate expressed in warmer air and ocean temperatures across the globe. Although a result of orbitally-forced summer insolation, the HTM constitutes a valuable parallel to the greenhouse-gas-driven setting of a current (and near-future) warmer world. At higher latitudes in the Northern hemisphere, the HTM has been proposed as an interval of reduced sea ice and increased Atlantic water inflow, similar to a projected future warmer Arctic Ocean. Two sediment archives elucidate the early Holocene HTM evolution of high Arctic seasonal sea ice in the northern Barents Sea (>80 °N), a key area for Atlantic-Arctic Ocean water interaction in a hotspot of current climate warming. HBI (highly-branched) biomarkers (IP₂₅, IPSO₂₅, HBI III, HBI IV) unequivocally demonstrate the persistence of spring seasonal sea-ice as high as 55% between 11.7 and 9.1 cal ka BP. Concomitant high δ18O in benthic foraminifera and elevated phytoplankton biomarker (HBI III, HBI IV) concentrations indicate the influence of warm Atlantic-derived bottom water and peak bioproductivity, respectively. Our results highlight the nuanced and complex cryospheric response to climate warming, showing High Arctic sea ice persisting in a setting of warmer-than-present spring and summer conditions under a concomitant increased inflow of subsurface Atlantic Water. This raises important questions about the fate of Arctic sea ice, oceanography, and ecosystems (including commercially important fisheries) in an increasingly warmer climate driven by anthropogenic factors.
Szeligowska M*¹
¹Institute of Oceanology Polish Academy of Sciences, Sopot, Poland
The retreat of tidewater glaciers and them becoming land based is expected to decrease the productivity of the polar fjords as a result of, among others, changes in nutrient supply, stratification and transport of particulate and dissolved matter from land. However, as polar coastal waters expand due to the loss of marine ice, these newly ice-free areas are claimed by primary and secondary producers, and they might act as new and considerable sinks of atmospheric carbon. Thus, this work aimed to map the changes in the glacial bays’ area in the West Spitsbergen fjords by using summer-time Landsat satellite images (1976-2022) and estimate gains in primary and zoobenthic production and carbon burial using existing regional data. In the period 1976 – 2022, the West Spitsbergen glacial bays with marine-terminating glaciers increased by around 200 km², with the highest contribution from Hornsund (around 100 km²). Importantly, the surge event led to a decrease in the Van Keulenfjorden area by around 42 km². Due to the glacial dynamics, the net increases in primary production, zoobenthic production and organic carbon burial were estimated as 7.7, 1.6 and 2.0 Gg C per year, respectively. While these constitute only a fraction of the globally estimated rates, emerging marine habitats in the polar regions could gain more relevance considering the scale of marine ice loss and the high efficiency of organic carbon burial in fjords.
Sen A*¹², Sandig A³, Michel L⁴, Knies J⁵⁶
¹The University Centre in Svalbard, Longyearbyen, Norway, ²Nord University, Bodø, Norway, ³Wageningen University, Wageningen, Netherlands, ⁴University of Liége, Liége, Belgium, ⁵Norwegian Geological Survey, Trondheim, Norway, ⁶Centre for Ice, Cryosphere and Climate, Tromsø, Norway
Petroleum is well known to be highly prevalent in the Arctic, and arguably governs much of the commercial and political dynamics of the region. Though petroleum reserves tend to be located deep below the seafloor, recently the benthos in the Hopen Deep region south of Svalbard was observed to be saturated with petroleum; with oil even escaping into the water column and forming slicks on the sea surface. We used a highly interdisciplinary approach to characterize the ecology of the Hopen oil seep benthos and how the physical and chemical environment drives ecosystem function. Despite the presence of potentially toxic oil and gas, communities were diverse with high abundances of taxa. The local physico-chemical environment was measurably varied and heterogeneous, which drives site specific communities and species turnover, thereby increasing overall diversity. Chemosynthetically fixed carbon appears to be a major part of the food web, with contributions to higher level trophic levels surpassing what has been seen at Arctic gas seeps. The Hopen ecosystem appears thus to not be highly linked to photosynthesis which could suggest that oil seeps could affect pelagic benthic coupling (known to traditionally be tight on Arctic shelves). Since the Hopen seep covers a large area of the seafloor, and there is potential for similar systems to exist across the Arctic, the presence of such ecosystems should be considered in key processes within the Arctic marine ecosystem.
Rosland M*¹, Hatlebakk M¹, Søreide J², Aberle N¹³
¹Norwegian University of Science and Technology, Trondheim, Norway, ²University Centre in Svalbard, Longyearbyen, Norway, ³Hamburg University, Hamburg, Germany
Plankton are the basis of marine food-webs and are good indicators of the impact of climate change on marine ecosystems. It is ideal to study plankton in the Barents Sea as they are adapted to both the Arctic and Atlantic water flowing in. Phytoplankton usually forms intense blooms in the spring, but in winter the low irradiance due to ice-cover and deep mixing, lead to sparse biomass of plankton. Fall and winter seasons are times of the year where little knowledge about plankton dynamics exists due to limited access to these areas during the dark period. Here we present seasonal data from the Nansen Legacy cruises in August and December 2019 and March and May 2021 taken from stations P1, P4 and P7 in the Barents Sea, to study plankton dynamics and food-web interactions. The aim was to analyse seasonal growth and grazing rates of phytoplankton, micro-/mesozooplankton and copepods and to compare these between seasons. Based on dilution experiments, estimates on growth and grazing rates of plankton organisms were obtained. Data analyses showed that Bacillariophyceae were the most abundant phytoplankton group in spring, with the most abundant genus being Fragilariopsis spp. and Thalassiosira spp., while unspecified flagellates and the dinoflagellate Gymnodinium spp. dominated the plankton in the winter. Overall, a higher abundance and diversity of phytoplankton was found in the spring compared to the winter, an observation that is in line with previous findings from the Barents Sea ecosystem.
Palacz A¹, Grigoratou M*², Briggs N³, Ciavatta S², Greco M⁴, Kedra M¹, Koski M⁵, Lindemann C⁶ ⁷, Visser A⁵, Yumruktepe VÇ⁸, Wiedmann I⁹
¹Institute of Oceanology of Polish Academy of Sciences, Sopot, Poland, ²Mercator Ocean International, Toulouse, France, ³National Oceanography Centre, Southampton, UK, ⁴Spanish National Research Council, Barcelona, Spain, ⁵DTU Aqua, Copenhagen, Denmark, ⁶Norwegian Institute for Water Research, Bergen, Norway, ⁷University of Bergen, Bergen, Norway, ⁸Nansen Environmental and Remote Sensing Center, Bergen, Norway, ⁹UiT The Arctic University of Norway, Tromsø, Norway
Significant knowledge gaps remain in mapping and forecasting future changes in marine carbon cycling. In particular, the changing role of biological processes in the uptake and sequestration of carbon from the atmosphere remains highly uncertain. At the same time, there has long been a mismatch between data needed to inform and evaluate climate and ecosystem models, and data products available from in-situ and remote sensing observations. The challenge is even bigger in the polar regions, especially in the Arctic, where we observe the greatest impacts of climate change while suffering from a scarcity of observations. Insufficient or ineffective communication among researchers across the observations-modeling interface as well as across the interface of inorganic-organic carbon variables exacerbates the problem. Here we will present the preliminary results of a working group action organized by the Horizon2020 project ECOTIP and EU4OceanObs projects. The action brings together a group of multidisciplinary experts from both the observing and modeling communities to agree on a priority list of biological and biogeochemical data products that are crucial for advancing the modeling of the biological carbon pump in the Arctic seas. We will also illustrate the integration of these data products with international efforts like the Integrated Ocean Carbon Research, the GOOS specification sheets, Copernicus Green Ocean, and IPCC reports.
Nowicki R*¹, Borgå K², Wing Gabrielsen G¹³, Søreide J¹, Varpe ع⁴⁵
¹The University Centre in Svalbard, Longyearbyen, Svalbard, Norway, ²University of Oslo, Oslo, Norway, ³Norwegian Polar Institute, Tromsø, Norway, ⁴Norwegian Institute for Nature Research, Bergen, Norway, ⁵University of Bergen, Bergen, Norway
A fundamental adaptation of many Arctic marine organisms is the development of large, lipid-rich energy stores, such as to withstand seasonal periods of low productivity. As a result, many species undergo pronounced seasonal changes in body condition, as energy stores are built up and depleted over an annual cycle. Polar cod (Boreogadus saida) is a key, energy dense, fish species in Arctic marine ecosystems, acting as a trophic connection between primary consumers and higher trophic levels. We collected polar cod from the Barents Sea during early spring (March), late spring (April/ May), late summer (August) and early winter (November/ December). We use morphometric parameters (length and weight) and condition indices (hepatosomatic and gonadosomatic index) to assess seasonal variations in body condition. Preliminary results show body condition varied seasonally, being significantly lower in spring months compared to summer and winter. We establish relationships of body condition, age, and sex, to assess potential seasonal variations occurring through a life cycle and associated with reproduction. We also directly measure energy content (kilojoules per gram, dry weight) using calorimetry, estimate seasonal changes in energy content and analyse relationships between body condition and energy content. Such seasonally resolved baselines will give insight into the resilience of this key species to intensified environmental and anthropogenic stressors expected in a future Arctic.
McKay R*¹, Osanen J¹, Else B², Michel C³, Campbell K¹
¹UiT The Arctic University of Norway, Tromsø, Norway, ²University of Calgary, Calgary, Canada, ³Fisheries and Oceans Canada (DFO), Winnipeg, Canada
The heterogeneity of sea ice microorganism communities presents a challenge in our understanding of sea ice primary production and its representation in modelling future scenarios. While most studies focus on the bottom centimeters of sea ice, less is known of how net community production (NCP), which is the balance between microbial photosynthesis and metabolic respiration, changes throughout the vertical profile of the ice column. In this study, two locations of land-fast first-year sea ice were routinely sampled 27 April to 4 June 2022 over a spring bloom near to the community of Cambridge Bay and the Canadian High Arctic Research Station (CHARS). Sample sites were selected due to their contrasting sub-ice turbulence regimes that are thought to promote differences in nutrient availability. Overall, comparatively low NCP and chlorophyll a values were observed in this region, however, variability in bloom magnitude and composition were found to be influenced by turbulence driven nutrient levels. Patterns within this inter-site comparison emerge as measurements of NCP, flow cytometry, DOC, POC and chlorophyll a are explored relative to turbulence driven nutrient availability. The study highlights the changes brought about by different turbulence regimes throughout spring melt and presents some of the first measurements of NCP throughout the ice column in the Arctic. The study is a component of the BREATHE (Bottom-sea ice Respiration and nutrient Exchanges Assessed for THE Arctic) research project funded by the Norwegian Research Council.
Mazurkiewicz M¹, Pawłowski J¹, Pawlowska J¹, Barrenechea Angeles IA², Grzelak K¹, Deja K¹, Zaborska A¹, Włodarska-Kowalczuk M*¹
¹Institute of Oceanology Polish Academy of Sciences, Sopot, Poland, ²UiT The Arctic University of Norway, Tromsø, Norway
Arctic coastal ecosystems are increasingly exposed to dramatic environmental changes and multiple stressors arising from climate warming. The effects of these stressors on benthic biodiversity have been well recognized for large size biota (macrozoobenthos) analyzed using traditional (morphology based) methods. In this study we applied sediment eDNA together with morphology-based species inventories to compare the effects of glacially mediated disturbance on benthic macrofauna, meiofauna and Foraminifera in a Svalbard fjord. Three genetic markers targeting metazoans (COI), meiofauna (18S VIV2) and Foraminifera (18S 37f) were used. Macrofauna (analysed morphologically) showed a clear change in taxonomic composition and a dramatic cline in diversity in response to glacially mediated disturbance. Such patterns were not observed for macrofauna taxa recorded in metabarcoding datasets. Nematoda and Foraminifera morphological and molecular data demonstrated a gradual change in both alpha diversity and taxonomic composition and more subtle responses to environmental changes along the fjord axis. These differences indicate that patterns of response described for macrobenthos (most commonly used in impact studies) should not be directly transposed to meiofaunal biota. The study also confirms the usefulness of sedimentary DNA metabarcoding as a complementary tool to assess the biodiversity changes in Arctic ecosystems, particularly suitable for analysis of meiobenthos.
Majaneva S*¹², Martell L³, Soto Angel J³, Verhaegen G⁴, Mańko M⁵, Ronowicz M⁶, Hosia A³
¹Akvaplan-niva, Trondheim, Norway, ²Norwegian University of Science and Technology, Trondheim, Norway, ³University of Bergen, Bergen, Norway, ⁴Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany, ⁵University of Gdańsk, Gdańsk, Poland, ⁶Institute of Oceanology PAN, Sopot, Poland
Gelatinous zooplankton are a key component of Arctic communities, with central roles in trophic networks and the biological carbon pump. Yet, data on them remain scarce, and they are often neglected in zooplankton and benthic surveys due to perceived methodological challenges as well as identification difficulties. With the Arctic facing rapid anthropogenic changes, there is a dire need for baseline biodiversity and ecological data on the gelatinous zooplankton. We argue that simple measures to include these organisms in zooplankton and benthic surveys from the planning phase can substantially increase both data gain from the sampling effort and our understanding on the structure and functioning across the entire pelagic community, as well as benthic-pelagic coupling. Here, we show that engaging gelatinous zooplankton specialists and slightly modifying sample processing workflows can generate substantial data on gelatinous zooplankton diversity, distributions, and abundances without the need to necessarily increase sampling effort. Such data are fundamental for establishing a holistic baseline of ecosystem structure and functioning as well as a solid foundation for future work on metabarcoding and eDNA applications for monitoring biodiversity, ecosystem functioning, and climate impacts.
Kvernvik AC*¹, Gabrielsen TM², Krabberød AK³, Vader A¹
¹University Centre in Svalbard (UNIS) Longyearbyen, Norway, ²University of Agder, Kristiansand, Norway, ³ University of Oslo, Oslo, Norway
Phytoplankton are the base of the Arctic food web, and changes here will be the first sign of ecosystem shifts, with unknown consequences for the Barents Sea ecosystem. Productivity patterns in Arctic phytoplankton are controlled by many physical and chemical factors where the availability of light and nutrients are deemed most important. The light climate in the Arctic is primarily controlled by seasonal changes in solar elevation, ranging from periods of midnight sun (polar day) to periods when the sun remains below the horizon (polar night). The duration of sea ice cover, ice thickness, snow cover, and mixed layer depths are also key parameters influencing the light climate in the Arctic. To cope with variable light climate, phytoplankton employ various mechanisms involving short- and long-term physiological changes. Each species of phytoplankton possesses distinctive adaptive characteristics that determine its distribution and activities. Increasing our understanding of these adaptations enables better prediction of their occurrence and the consequences of environmental changes on phytoplankton communities. To address this, we used metatranscriptomics, which involves transcript sequencing from the entire community, from different seasons and along a north-south transect in the Barents Sea. This approach provides a snapshot of the main active organisms and the predominant activities performed by a specific community in response to changing conditions.
Kuklinski P*¹, Iglikowska A², Borszcz T¹, Chelchowski M¹, Kedra M¹, Przytarska J¹, Hop H³, Humphreyes-Williams E⁴, Najorka J⁴, Ronowicz M¹, Sowa A¹, Włodarska-Kowalczuk M¹, Drewnik A¹, Grabowska M¹, Krzemińska M¹, Voronkov A⁵, Piwoni-Piórewicz A²
¹Institute of Oceanology Polish Academy of Sciences, Sopot, Poland, ²University of Gdansk, Gdansk, Poland, ³Norwegian Polar Institute, Tromsø, Norway, ⁴The Natural History Museum, London, United Kingdom, ⁵Institute of Marine Research, Tromsø, Norway
Calcifiers are organisms that produce calcareous skeletons. Their skeletal CaCO3 consists of mainly Ca2+ and CO32- but also a range of minor and trace elements. Due to warming, sea-ice retreat in the Arctic Ocean is leading to higher pCO2 values in the surface waters reducing CaCO3 saturation state. Carbonate undersaturation in the water may impact calcareous skeletons in many ways e.g., carbonate dissolution. Yet to what degree these changes will influence organisms depend on level of biological versus environmental control of their calcification processes. Organisms with a strong biological control will be able to withstand external environmental variations as they can adapt to changes over time. We analysed mineralogical and chemical content of all major calcifying benthic biota occurring in the Arctic waters including Bryozoa, Echinodermata, Brachiopoda, Mollusca and Crustacea from locations differing in environmental conditions. All together 1271 specimens belonging to 165 species were analysed. The mineralogy of skeletons was found to be group-specific e.g., echinoderms were exclusively calcitic while gastropods mostly aragonitic. Species-related differences in element concentrations were statistically significant and occurred regardless of environmental differences. This observation implies the dominance of biological processes regulating mineralogical and elemental uptake into the skeleton over factors related to the variability of abiotic environmental conditions.
Jungblut S*¹, Niklass J², Brand M³, Buschbaum C⁴, Paar M⁵, Bartsch I⁶, Molis M²
¹Marine Botany, University of Bremen, Bremen, Germany, ²UiT The Arctic University of Norway, Tromsø, Norway, ³Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Helgoland, Germany, ⁴Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, List/Sylt, Germany, ⁵University of Rostock, Rostock, Germany, ⁶Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
Many parameters of the marine physical environment of the Arctic are rapidly changing. Especially in coastal areas the ongoing cryosphere loss has profound effects on shallow subtidal habitats and communities, including shifts in distribution of seaweed biomass and species composition along the depth gradient. The objective of this study was to assess whether and, if so, by how much biomass, total abundance, and taxon composition of the seaweed-associated fauna had changed concomitantly. In Kongsfjorden, Svalbard, the seaweed-associated fauna at Hansneset has been sampled at 2.5, 5, 10, and 15 m in 1996/98, 2012/13, and 2021. Taxonomic composition differed considerably between 1996/98 and 2012/13, while it remained similar to the latter in 2021. Taxonomic composition varied also with depth and this effect was independent on year of observation. The fauna biomass increased with depth between 2.5 and 15 m in 1996/98. Contrarily, it decreased with depth in 2012/13. In 2021, peak biomass was found at 5 m depth, while the remaining depths showed similar values of about 30-50% less. Overall, biomass and abundance of the seaweed-associated fauna increased about twofold, on average, between 2012/13 and 2021, returning to 1996/98 values. While mainly cirripeds caused this increase in biomass, the biomass of bryozoans decreased from 2012/13 to 2021.
Hatlebakk M*¹, Viljanen M¹, Grant S¹, Johnsen G¹²
¹Norwegian University of Science and Technology, Trondheim, Norway, ²University Centre in Svalbard, Longyearbyen, Norway
Light is the most important cue of life, regulating individual behavior and synchronizing behavior within and across species. Though the polar night is perceived as dark for the human eye, the light climate is highly dynamic with several ambient light sources detectable for the arctic organisms: Diffused light from the sun below the horizon, the moon which can increase the light by 100-fold from new to full moon, aurora borealis can be strong enough to be detected, and artificial light is becoming more abundant with increasing human activity in the Arctic. By acoustic measurements, it has been observed that the zooplankton perform vertical migration following the moon cycle during the polar night. In spring and fall when diel vertical migration is mediated by the sun, this is linked to optimizing feeding in the photic zone vs predator avoidance by hiding at depth at night. Preliminary results from the polar night indicate that the microplankton community is active and responding to light intensities similar to that of the full moon, thus locating the scarce food resources may potentially be less costly at certain phases of the moon cycle. In January 2023, experiments were conducted to investigate the activity level of Calanus copepods through the different moon phases by incubating them under light conditions imitating the moon cycle. Animals were observed in a dark room for video recording, with the aim of investigating if swimming activity changes through the moon phases.
Goraguer L*¹², Assmy P¹, Kohlbach D¹, Chierici M³, Dąbrowska AM⁴, Gradinger R², Jones E³, Marquardt M², Tatarek A⁴, Vader A⁵, Wiktor JM⁴, Wold A¹
¹Norwegian Polar Institute, Tromsø, Norway, ²UiT The Arctic University of Norway, Tromsø, Norway, ³Institute of Marine Research, Tromsø, Norway, ⁴Institute of Oceanology Polish Academy of Sciences, Sopot, Poland, ⁵The University Centre in Svalbard, Longyearbyen, Norway
The Barents Sea experiences strong seasonal variability. The observed increase of warm Atlantic water inflow results in reduction of sea ice cover and influence the timing, duration, magnitude, and protists composition of the blooms. In this study, we assess the relationship between the spatial and seasonal variability in protist plankton biomass and taxonomic composition in the northwestern Barents Sea. Sampling was conducted during March, May and July 2021, August 2019, August 2018 and December 2019. Depth-integrated stocks of major groups of protists (diatoms, dinoflagellates, flagellates, and ciliates), and environmental factors as sea-ice extent, temperature, salinity, inorganic nutrients, chlorophyll a, particulate organic carbon and nitrogen concentrations were investigated. Spring bloom was recorded between May and July, which started earlier in Atlantic-influenced waters. Diatoms of the genus Thalassiosira were dominant, while mixotrophic flagellates, dinoflagellates and ciliates contributed significantly to protist biomass in August, with interannually difference due to earlier and more extensive sea ice retreat in 2018 compared to 2019. In winter, Chl a concentrations were low. Dinoflagellates (especially genus Gymnodinium) dominated the community in December and March with ciliates being abundant at some regions in December. The observed succession differences reflected the water masses (Atlantic versus Arctic) and the duration of the ice cover ones.
Giebichenstein J*¹, Harju M² , Varpe س, Gabrielsen GW⁴, Andersen T¹, Borgå K¹
¹University of Oslo, Oslo, Norway, ²Norwegian Institute for Air Research (NILU), Tromsø, Norway, ³University of Bergen, Bergen, Norway, ⁴Norwegian Polar Institute, Tromsø, Norway
Arctic marine organisms are susceptible to multiple stressors, such as climate change, increased human activities such as fisheries and tourism, and pollutant exposure. Combined, these stressors are expected to alter food web composition and the transport, fate, and effect of pollutants within it. In a highly seasonal environment that can directly impact pollutant availability, storage, and transformation, knowledge of annual pollutant dynamics is crucial, particularly during the understudied polar night. We therefore analyzed chemical and dietary descriptors to determine how seasonal changes in energy acquisition and allocation impact annual dynamics of pollutant accumulation and transfer in the pelagic Barents Sea food web. Chemicals analyzed included a wide range of persistent organic pollutants such as DDT and PCBs in eleven different taxa, spanning from copepods (Calanus spp., Calanus hyperboreus) to macrozooplankton (Themisto spp., Thyssanoessa spp., Meganyctiphanes norvegica, Chaetognatha, and Clione limacina) to fishes (Boreogadus saida, Mallotus villosus, Gadus morhua). As diet is one of the main uptake routes of pollutants into biota, we measured stable isotopes of carbon (δ¹³C) and nitrogen (δ¹⁵N). These yield time-integrated information about an organism’s carbon source and trophic position, to assess the food web structure and link pollutant levels with diet across the seasons.
Gawinski C*¹, Daase M¹², Ormańczyk MR³, Kwasniewski S³, Svensen C¹
¹UiT The Arctic University of Norway, Tromsø, Norway, ²The University Centre in Svalbard, Longyearbyen, Svalbard, Norway, ³Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland
Zooplankton show strong seasonal variations in abundance, biomass, and production in Arctic marine ecosystems, due to seasonal changes in food availability and quality. Because of the difficulties of conducting research in the Arctic in winter, copepod reproductive rates for this time of the year are poorly understood but are essential for assessing population dynamics and calculating secondary production in an annual context. Here, we present estimates of annual copepod secondary production, covering Atlantic to Arctic influenced domains in the northern Barents Sea (76 °N to 82 °N). In our calculations we used weight-specific egg production rates obtained from experiments conducted in August and December 2019, October 2020, and March, May, and August 2021 at temperatures between -1.5 and 3 °C aboard R/V Kronprins Haakon. We made comparisons with production estimates based on a widely used growth rate model by Hirst and Lampitt (1998). In spring most of the copepod secondary production was from large copepods of the genus Calanus, while in summer, autumn and winter the greater part of secondary production of copepods was from small-sized taxa.
Ferrando S¹², Carlig E³, Aicardi S¹, Christiansen JS⁴, Lynghammar A⁴, Karamushko OV⁵, Rask Møller P⁶, Ghigliotti L*³
¹DISTAV - University of Genova, Genoa, Italy, ²National Biodiversity Future Center, Palermo, Italy, ³National Research Council of Italy, Institute for the study of the Anthropic impacts and the Sustainability of the marine environment (IAS), Genoa, Italy, ⁴Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway, ⁵Murmansk Marine Biological Institute, Murmansk, Russia, ⁶Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark
The ice cod Arctogadus glacialis is a gadid species endemic of the Arctic Ocean. It is mainly associated to coastal habitats and continental shelves, sometimes in brackish waters. Despite a circumpolar distribution, and coastal preference, information on the life history and reproductive features of A. glacialis is sparse. The time of spawning is controversial and both winter and summer spawning have been suggested. However, specimens with well-developed gonads have not been reported prior to the present work. In the frame of the international TUNU Programme (UiT The Arctic University of Norway), we studied the reproductive traits of A. glacialis collected in September 2022 during the TUNU VIII expedition to Northeast Greenland. A. glacialis occurred at all sampling locations, with peak abundances in secluded fjords such as Bessel Fjord and Brede Fjord. Here we report on the results of integrated macroscopic and histological analyses of gonads from 12 adult (female N=7, male N=5) A. glacialis collected in Brede Fjord. With a total length ranging between 225 to 355 mm, the analyzed specimens were larger than other conspecifics studied so far for reproductive traits. Macroscopic examination of the gonads showed only one immature female, whereas eleven specimens were clearly mature and in a pre-spawning state with gonadosomatic indices ranging between 8-15% for females and 7-10% for males.
Eikrem W*¹², Vader A³, Hofgaard A⁴, Edvardsen B⁴
¹Norwegian Institute for Water Research, Oslo, Norway, ²Natural History Museum, University of Oslo, Oslo, Norway, ³The University Centre in Svalbard, Longyearbyen, Norway, ⁴Department of Biosciences, University of Oslo, Oslo, Norway
At the southern-most station along the S-N transect, P7, the pelagic protist community was characterized by both high diversity and abundance. Large diatom species dominated the community, and large dinoflagellates and Phaeocystis pouchetii were also abundant. Moving north and into the ice, the protist community in the water column changed. Smaller organisms and heterotrophic species became more prominent. The larger diatom species became much scarcer but were still present. The community in the ice cores was dominated by pennate diatoms, but dinoflagellates and in particular the heterotrophic species were also abundant. In addition, green flagellates, cryptomonads, chrysophytes, and haptophytes were frequent. The sea-ice showed the highest chlorophyll-a values and had larger cells. In the melt ponds the salinity was low, but variable (2.8-5.7). The chlorophyll-a values there were low, and the species composition varied, and the taxa present were associated with brackish and freshwater as well as a benthic lifestyle.
Durazzano T*¹, Svensen C¹, Visser A², Søreide J³, Hop H⁴
¹UiT The Arctic University of Norway, Tromsø, Norway, ²DTU Technical University of Denmark, Lyngby, Denmark, ³UNIS University Centre in Svalbard, Longyearbyen, Norway, ⁴Norwegian Polar Institute, Tromsø, Norway
Copepods are crucial in the Arctic marine pelagic ecosystem as they serve as a vital link between microbial processes and higher-level consumers. They are present in most aquatic environments and constitute a large fraction of mesozooplankton in the pelagic realm, approximately 70% of the total biomass. They also show a wide range of different ecological roles. Furthermore, copepods are good environmental indicators as they react strongly to changes in the water column. They also have high abundances and short life cycles; hence, they are excellent candidates for the study of ecosystem responses to climate variability because populations have the potential to reflect event-scale changes. However, our understanding of copepod assemblages and their functional roles is still limited, especially at high latitudes. Given that the Arctic shows extreme seasonality and a greatly variable oceanic environment and that such environmental variability affects the respective copepod community structures, it is crucial to address this gap in knowledge and evaluate copepod community structures in different seasons. A cutting-edge approach to unveiling the structure of planktonic communities is "trait-based ecology". One of its primary goals is to predict how ecosystems function and how they will change in response to perturbations based on information about the distribution of traits within the species pool. This approach focuses on the individual and its measurable characteristics, known as functional traits. Functional traits are essential in capturing an individual's Darwinian fitness, which refers to their reproductive success. In this approach, the individual is considered the primary level at which selection and adaptation occur. Therefore, the performance and responses of individuals affect those of populations, communities, and ecosystems. To study seasonality, it is not only important to relate abundances and distributions, but there is also a need to gain a functional understanding of how different seasons shape community structures and their ecological services. In order to do so, it is possible to group functionally similar species based on their functional traits. These usually occupy distinct ecological niches, and the ecosystem processes related to these groups are expected to vary across seasons. Defining the community structure in relation to seasonality is important to better understand the underlying seasonal environmental drivers. This approach is here used to model copepod community assemblages in the Barents Sea.
Duarte P*¹, Castro De La Guardia L¹
¹Norwegian Polar Institute, Tromsø, Norway
The upscaling of pelagic and sympagic primary production (PP) over large ocean regions is challenging due to the lack of in situ measurements at high spatial and temporal resolution and the lack of remote sensing techniques for ice covered areas, or else, for areas with high cloud cover. We present results obtained with a coupled ocean and sea ice physical-biogeochemical model, implemented for a large region around Svalbard at 4 km horizontal resolution (S4K). The model is based on the two-way coupling of the Regional Ocean Modeling System and the Los Alamos Sea Ice Model. The ocean is resolved vertically in 35 terrain following coordinates, whereas 7 layers are considered for the sea ice and one for the snow. Biogeochemical (bgc) processes are computed for the ocean by a dynamically stoichiometric model including nutrients, dissolved oxygen, inorganic carbon, diatoms, flagellates, and detritus. In the case of sea ice, the bgc model includes nutrients and diatoms and corresponding processes are computed over the vertical extent of the brine network, using a bgc dynamic grid. Model results were used to compute phytoplankton and ice algal PP in the North-West Barents, with the former ranging between 20 and 60 gC mˉ² yrˉ¹, and the latter ranging between 0.15 and 0.3 gC mˉ² yrˉ¹, leading to a total production of ~9 TgC, of which 0.4% can be attributed to ice alga. We use the model results to quantify the relative role of different drivers on interannual PP variability.
Wang C*¹, Wang J¹, Debernard J¹
¹Norwegian Meteorological Institute, Oslo, Norway
The Arctic sea ice has been undergoing a dramatic decrease in recent decades, in particular in September when the Arctic sea ice is at the minimum. The sea ice decline in the Barents-Kara Sea is responsible for one-third of the pan-Arctic winter sea ice loss over the past four decades. In particular, the northern Barents Sea hosts the most pronounced loss of Arctic winter sea ice. The Barents Sea is experiencing exceptional warming, which is strongly connected to the reduction of sea ice and increase of SST. Numerical simulations showed that the sea surface heat flux contributed 80% of the increase in energy of the upper layer of the Arctic Ocean. Thus, the surface heat flux plays an important role in the Arctic climate system. Barents-2.5 km is a primarily operational ocean and sea ice modeling and prediction system at met.no. It is a full coupled ocean (ROMS) and sea ice (CICE) model covering the Barents Sea and areas around Svalbard, and forced with a high resolution numerical weather prediction (NWP) system, Arome-Arctic. Using the remote sensing products of CERES-SYN and reanalysis data of ERA5, the surface heat fluxes in Barents-2.5 km were validated and evaluated.
Schlichtholz P*¹
¹Institute of Oceanology of the Polish Academy of Sciences, Sopot, Poland
Winter atmospheric variability in the Arctic-Eurasian region is investigated in relation to the previous summer anomalies of Atlantic Water temperature (AWT) in the Barents Sea using observations and reanalysis data from the period 1978-2018. The emphasis is on differences between the LATE and EARLY epochs selected based on a large sea-ice loss in the Barents-Kara Seas in the mid-2000s. It is shown that the linkages of Eurasian climate variability to the AWT anomalies that were significant in the EARLY epoch deteriorated in the LATE epoch. In particular, the detrended AWT anomalies explained 77% of the interannual variance of lower-tropospheric synoptic eddy activity (poleward eddy heat flux at 925 hPa) over northern Eurasia and 55% of the interannual variance of surface air temperature over midlatitude Eurasia in the EARLY epoch but a negligible fraction (<5%) of these variances in the LATE epoch. Analysis of sea surface temperature variability in the Arctic-North Atlantic region shows that the strong Arctic-Eurasian linkages in the EARLY epoch may have resulted from the atmospheric response to a large-scale surface re-emergence of ocean temperature anomalies. The features of winter Eurasian climate variability that have lost their connection to coherent ocean temperature anomalies in the Arctic-North Atlantic region have become related to other predictors.
Mohamed B*¹², Nilsen F³, Skogseth R³, Rose S⁴
¹GeoHydrodynamics and Environment Research (GHER), University of Liège, Liège, Belgium, ²Oceanography Department, Faculty of Science, Alexandria University, Alexandria, Egypt, ³Department of Arctic Geophysics, University Centre in Svalbard, Longyearbyen, Norway, ⁴National Space Institute, Technical University of Denmark, Lyngby, Denmark
Global sea level rise (SLR) is one of the most certain consequences of climate change. However, this rise is neither uniform in time nor in space but varies depending on both the time period considered and the geographic region. The Barents Sea (BS) is considered one of the most vulnerable regions to climate change, as it is expected to be ice-free by the middle of this century. In this context, this work aims to quantify relevant sea level changes in the Barents Sea over the period (1993 -2020) by calculating trends and variations in the main driving forces of sea level, including thermosteric, halosteric, and atmospheric contributions. To this end, we used gridded satellite-based sea level anomalies (SLA) provided by the Denmark Technical University (DTU) to estimate overall SLA variability, reanalysis of temperature and salinity profiles to estimate thermosteric/halosteric contribution, and ERA5 data for atmospheric contribution. Our preliminary results show that the basin’s average SLR between 1993 and 2020 is about 2.35±0.45 mm/year. Significant spatial variability in SLA trends is observed, with the maximum trend (up to 5 mm/year) in the southern Barents Sea, while non-significant (p > 0.05) trends are observed in the northern Barents Sea. The thermosteric effect is the main factor contributing to sea level rise in most areas of BS, especially in the south BS, which is largely influenced by the inflow of warm Atlantic water. In the northeastern part of BS, the halosteric trend acts to increase the steric sea level, while in the western and southern parts, the halosteric trend leads to a decrease in sea level. The trend of the atmospheric component shows a very small and non-significant contribution to the trend of the sea level in the whole region.
Sortland JM*¹², Renner A², Skarðhamar J², Itkin P¹, Koenig Z³
¹Department of Physics and Technology, UiT The Arctic University of Norway, Tromsø, Norway, ²Institute of Marine Research, Tromsø, Norway, ³Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway
The Barents Sea is an important inflow shelf to the Arctic Ocean where water mass modification and transformation processes take place that can have major impact on stratification and the halocline in the Eurasian Central Arctic. In this study, we analyse hydrographic conditions and circulation patterns on the Nansen Legacy (NL) main transect, a south-to-north section involving 25 stations across the central Barents Sea and the continental slope north of Svalbard. In particular, we examine seasonal variations in water mass characteristics and distribution, including properties and location of the Polar Front, and circulation patterns across the NL transect and their impact on water mass transformation. The dataset includes CTD, S-ADCP and L-ADCP profiles collected along the transect during 11 NL cruises between 2018-2022, with special focus on the NL joint cruises (JC2-1 and JC3) and the Q-cruises (Q1, Q2, Q3 and Q4). We investigate atmospheric drivers, such as wind and air temperature, and sea ice conditions, including concentration and other ice properties from remote sensing, to assess the physical drivers causing modifications of the water column properties.
Tao D¹², Rosendahl A¹, Li C¹²³
¹Geophysical Institute, University of Bergen, Norway, ²2Bjerknes Centre for Climate Research, Norway, ³Lamont-Doherty Earth Observatory, Columbia University, USA
Cyclones with different origins have different warming impacts in the Arctic region. We investigate wintertime cyclones in the Arctic-Atlantic corridor (Greenland Sea, Norwegian Sea, Barents Sea) sorted according to cyclogenesis location in the 1) midlatitudes, 2) subarctic region or 3) high Arctic region. Thermodynamically, these cyclone groups differ in their vertical profiles of area-mean equivalent potential temperature. The midlatitude group has the warmest cyclones overall, but the Arctic and subarctic groups have much larger spreads, including very cold cyclones as well as warm ones whose profiles reach values close to the warmest ones in the midlatitude group. Warm cyclones in all groups are accompanied by a tilted North-Atlantic jet stream, but for the subarctic and Arctic group, the jet configuration is essential in transporting warm, moist air to high latitudes prior to cyclogenesis. Cold cyclones in the high Arctic group are associated with a distinct circulation pattern featuring a jet stream positioned far to the south. Elucidating the atmosphere’s role in preconditioning the large-scale environment is thus key to understanding the warming effect of Arctic cyclones.
Kolbe M*¹², Sonnemans J³, Bintanja R¹², van der Linden E², van der Wiel K², Whan K², Benedict I³
¹University of Groningen, Groningen, Netherlands, ²Royal Netherlands Meteorological Institute, De Bilt, Netherlands, ³Wageningen University and Research, Wageningen, Netherlands
The projected increase in poleward moisture transport (PMT) towards future warming has mainly been linked to the larger moisture holding capacity of warmer air masses. However, the future of interannual fluctuations of PMT and associated driving mechanisms are fairly uncertain. This study demonstrates the extent to which atmospheric rivers (ARs) explain the interannual variability of PMT, as well as related variables such as temperature, precipitation, and sea ice. Such linkages help to investigate whether extreme precipitation or melt events over Arctic regions are sensitive to the occurrence and intensity of ARs. To robustly study trends and interannual linkages of ARs and Arctic Climate, we detect and examine Arctic ARs in large ensemble runs of one present and two future climates (+2 °C and +3 °C), simulated by the global climate model EC-Earth. We found that the additional PMT to the Arctic in warmer climates is almost exclusively due to atmospheric rivers. Further, the amount of ARs reaching any Arctic region strongly depends on the mid-latitude jet location southwest of the region. Accordingly, they have a strong local effect on Arctic temperature, precipitation, and sea ice.
Koenig Z*¹, Lind S², Lundesgaard ز, Muilwijk M², Sandven H³, Assmy P², Assmann K⁴, Chierici M⁴, Fransson A², Gerland S², Jones E⁴, Renner AHH⁴, Granskog M²
¹UiT The Arctic University of Norway, Tromsø, Norway, ²Norwegian Polar Institute, Tromsø, Norway, ³University of Bergen, Bergen, Norway, ⁴Institute of Marine Research, Tromsø, Norway
The northwestern Barents Sea has experienced broad environmental changes since the mid-2000s, including rapid sea ice loss, ocean warming, and weakened stratification, with strong impacts on the marine ecosystems, known as Atlantification. While the interannual variability of the Barents Sea is well-documented, the seasonal evolution of the physical and biological systems is less known, mainly due to poor accessibility of the seasonally ice-covered area in winter and spring. Here, we use an extensive set of physical and biological in situ observations from four scientific expeditions covering the seasonal evolution from winter 2020/21 to late summer 2021. We found that sea ice meltwater and timing of ice-free conditions in summer shape the environment, controlling heat accumulation, nutrient availability, and biological activity vertically, seasonally, and meridionally. In March and May, the ocean was ice-covered and featured a deep mixed layer. Chlorophyll-a concentrations were generally low during this time, but they showed an increase from March to May, indicating the beginning of the spring bloom despite the absence of surface stratification. By July and in September, sea ice meltwater created a shallow low-density surface layer that strengthened stratification. In open water, chlorophyll-a maxima were found at the base of this surface layer as nutrients were depleted, while in presence of ice, it was closer to the surface. Solar heating and the thickness of the surface layer increased with the number of ice-free days. The summer data showed a prime example of an Arctic-like space-for-time seasonal variability in the key physical and biological patterns, with the summer situation progressing northwards along with sea ice retreat. The amount of sea ice melt (local or imported) has a strong control on the conditions in the northwestern Barents Sea, and the conditions in late 2021 resembled pre-2010 Arctic-like conditions with high freshwater content and lower ocean heat content.
Ivanov B*¹², Prokhorova Y¹, Bezgreshnov A¹, Juravski D¹
¹Arctic and Antarctic Research Institute, Saint Petersburg, Russia, ² Saint-Petersburg State University, Russia
Significant areas of sea ice are being redistributed from relatively thick flat ice to thinner and heavily hummocky ice under the observed warming conditions. According to various estimates, hummocks already account for 25 to 40% of the total amount of ice in the Arctic Basin, and this number is predicted to only increase. «Grounde true measurements» do not allow one to study the processes of energy exchange through hummocky ice. As a result, it is impossible to correctly estimate the albedo, temperature, and radiation balance of large hummocky surfaces. The nature and intensity of energy exchange processes in the presence of hummocky formations differ from the conditions observed on flat ice. In the spring-summer period, solar radiation determines the total heat flux from the atmosphere to the ice surface. There are proven parametrizations of the thermodynamic failure of flat areas of sea ice, but no parameterizations of energy exchange processes for areas occupied by hummocks. Thus, understanding the processes of energy exchange over areas occupied by hummocks make experimental studies extremely necessary and relevant. First, this concerns the determination of the albedo values, taking into account the areas occupied by hummocky and flat ice. Albedo determines the intensity of sea ice melt and plays an important role in the positive feedback mechanism. The albedo of flat and hummocky ice remains the same in modern mathematical models, which contradicts our experimental estimates. The results of using UAVs to estimate the albedo and surface temperature of hummocky surfaces were obtained in the Barents Sea (the «Transarctic-2019» expedition), on land-fast ice near arch. Severnaya Zemlya (Laptev Sea, 2021) and on the Svalbard glaciers (2019). The albedo and the temperature of hummocky areas turned out to be lower than similar estimates for neighboring areas of flat ice, which confirms our assumptions about the need to take into account these features when estimating the total heat exchange in the Arctic under the conditions of the observed warming.
Itkin P*¹, Divine D², Katlein C³, Raphael IA⁴, Shimanchuk E⁵, Ricker R⁶, Jutila A⁷, Salganik E², Neudert M³
¹UiT The Arctic University of Norway, Tromsø, Norway, ²Norwegian Polar Institute, Tromsø, Norway, ³Alfred Wegener Institute, Bremerhaven, Germany, ⁴Dartmouth College, Thayer School of Engineering, Hanover, USA, ⁵Arctic and Antarctic Research Institute, Saint Petersburg, Russia, ⁶NORCE Norwegian Research Centre, Tromsø, Norway, ⁷Finnish Meteorological Institute, Helsinki, Finland
Sea ice pressure ridge thickness and their consolidation state are variables relevant for sea ice mass balance, melt processes and ecosystem habitat. We show how both variables can be detected by multi-frequency electromagnetic induction (EMI). We validated the EMI results by collocating them to sea ice topography from airborne laser scanner, underwater topography from multi-beam sonar, sea ice thickness and structure from drill holes and temperature measurements from the thermistor chains. Low frequency in-phase channels give good estimates of total thickness, while high frequency quadrature channels give good estimates of consolidated layer thickness. The EMI measurement footprint depends on the depth of layer in question. It is larger for the total thickness than for the consolidated layer thickness. The footprint size makes the method appropriate for detection of relatively shallow ridges (6 m). Snow depth is an important limiting factor for the winter ridge consolidation, when the ocean heat fluxes are low or even negative. In spring positive ocean heat fluxes erode the ridge keels fast. Our case study from the MOSAiC expedition also shows winter progression of ridge consolidation.
Isaksen K*¹, Nordli ع, Køltzow MA¹, Aaboe S², Gjelten HM¹, Mezghani A¹, Eastwood S¹, Førland E¹, Benestad RE¹, Hanssen-Bauer I¹
¹Norwegian Meteorological Institute, Oslo, Norway, ²Norwegian Meteorological Institute, Tromsø, Norway
The first automatic weather stations were established in the early 1990s in eastern and northern Svalbard. At the time, real time data were used in weather forecasting and for rescue missions. However, the initial recorded data were not stored in any databases and have not previously been available for scientific analysis. This new dataset documents the surface air temperature (SAT) development in the north and east that remained unexplored until now. Here, we present updated surface air temperature data to the year 2023 to study the recent warming and its spatial and temporal variability in Svalbard, and evaluate how well the most recent European Climate Medium Weather Forecast reanalysis data set (ERA5) and the recently released high-resolution Copernicus Arctic Regional ReAnalysis (CARRA) describe SAT-climatology and trends. We find an unprecedented warming rate of more than 2.5 °C per decade in northeastern Svalbard, with a high increase in autumn and winter, compared to other seasons. The observed temperature increase is in good agreement with the reanalyses. However, compared to ERA5, CARRA shows larger regional SAT trends and more spatial details. The warming is faster than hitherto known in this region and its spatial structure is primarily consistent with reductions in sea ice cover. The recent warming was punctuated by an increasing intensity of abrupt warming events, with far reaching regional effects related to e.g., extremes in heavy rainfall during winter.
Hart-Davis M*¹, Ray R², Andersen O³, Howard S⁴, Padman L⁵, Nilsen F⁶, Dettmering D⁷
¹Deutsches Geodätisches Forschungsinstitut, Technische Universität München, Munich, Germany, ²Geodesy & Geophysics Lab., NASA Goddard Space Flight Center, Greenbelt, USA, ³National Space Institute, Technical University of Denmark, Copenhagen, Denmark, ⁴Earth and Space Research, Seattle, USA, ⁵Earth and Space Research, Corvallis, USA, ⁶The University Centre in Svalbard, Longyearbyen, Norway, ⁷Deutsches Geodätisches Forschungsinstitut, Technische Universität München (DGFI-TUM), Munich, Germany
Ocean tides are a vital component of global ocean circulation. In the Arctic Ocean, tides affect ocean circulation and sea ice dynamics and thermodynamics. Significant advances have been made in global ocean tide models; however, difficulties remain in the Arctic due to the poorly-mapped bottom topography, the dynamical influence of sea ice, and limitations on satellite altimetry measurements due to the high latitudes and presence of sea ice. An additional factor is the limited network of in-situ tide gauges in the Arctic. In-situ measurements from tide gauges or ocean bottom pressure sensors are crucial sources of information that can be used to understand the spatial variability of tides and validate the advances made in modelled estimates. Global in-situ tidal constituent databases contain a limited number of observations in the Arctic with, for example, TICON-3 containing 111 above 60 °N and 21 above 70 °N, with the distribution of these measurements mainly being around North America. Here, we present the results of a concerted effort to produce a comprehensive dataset of tidal constituents in the Arctic region. This resulting dataset contains 691 measurements above 60 °N and 313 above 70 °N with a much greater spatial distribution across the Arctic Ocean. The dataset is quality assessed, appropriately flagged and compared to recent tide models to determine the reliability of the different data sources used and to allow for the ease of use of the dataset.
Eltoft T¹, Gerland S*² and the CIRFA 2022 shipboard science team
¹UiT The Arctic University of Norway, Tromsø, Norway, ²Norwegian Polar Institute, Tromsø, Norway
In April/May 2022, RV Kronprins Haakon was the platform for Norway’s first ship-based Arctic research expedition with a focus on satellite remote sensing of floating ice, visiting the western Fram Strait to collect ground truth data for the validation of satellite remote sensing products. The cruise was a main activity of the Centre for Integrated Remote Sensing and Forecasting for Arctic Operations (CIRFA). The expedition’s main goal was to collect ground-truth data for validating remote sensing products for sea ice, icebergs, and ocean. The science team consisted of 33 scientists and engineers from Norway and France. In addition to the planned studies in conjunction with satellite remote sensing, several other synergetic projects addressed changes in sea ice and ocean. Validation of sea ice remote sensing products tells us more about how accurate and reliable their information is. To retrieve ground-truth validation data at a multitude of spatial scales, especially for synthetic aperture radar (SAR) satellite imagery, the science team collected data and samples with surface information ranging in scale from micrometers, inferred from snow pits and sea ice coring sites, to kilometers, inferred from transects and drone data. In addition, autonomous sensors were deployed in sea ice and ocean to reveal sea ice and ocean changes and dynamics. Relevant validation parameters such as surface roughness, temperature, density, salinity, and internal microscopic structure of snow and sea ice were measured during stops in the ice. Ice and snow thickness was measured with transects walking along lines on the ice. A laser roughness profiler was used to reveal surface topography characteristics, and analysis of snow pit measurements and ice cores reveals physical properties of snow and sea ice. Validation of satellite remote sensing requires that the ground-based measurements are geographically co-located with satellite acquisitions and coincide in time. During the expedition, this was regularly achieved. A whole suite of satellite images was acquired, including scenes from the European Space Agency’s Sentinel-1 and the Canadian RADARSAT-2 satellites. The combined ground truth and satellite measurements will allow future studies to address important research questions in Arctic remote sensing and development of new technologies. Here, we will give an overview on the expedition and show some preliminary results from the data and sample analyses.
Divine D*¹, Steer A¹, Gerland S¹, Cristea A¹, Jones E², Fransson A¹, Chierici M², Itkin P³, Raffel B¹, Granskog M¹
¹Norwegian Polar Institute, Tromsø, Norway, ²Institute of Marine Research, Tromsø, Norway, ³UiT The Arctic University of Norway, Tromsø, Norway
Northern Barents Sea is experiencing rapid changes manifested in a number of observable variables with receding sea ice being one of the major indicators of the ongoing warming. Both the northern Barents Sea and adjacent Arctic Basin have been in the focus of the Norwegian national project Nansen Legacy - a novel and holistic Arctic research project providing integrated scientific knowledge on the rapidly changing marine climate and ecosystem required to facilitate a sustainable management of the area through the 21st century. Throughout a series of research cruises conducted in 2018-2022 a dedicated interdisciplinary dataset on climate and ecosystem of the area representing entire seasonal cycle has been collected. This includes a large collection of data covering various aspects of the physics of sea ice for the range of spatial scales, from in situ acquired during on-ice station work to regional scales, based on helicopter-borne sea ice surveys and remote sensing. This dataset is presently being systematized and analyzed both for future dedicated publications on northern Barents Sea sea ice, as well as for aiding studies on regional ecosystem and biogeochemical cycles. We will present an overview of some of the first results summarized so far and discuss interdisciplinary linkages of the Nansen Legacy sea ice physics work to studies such as ecosystem research and environmental management.
Dall´Osto M*¹
¹ Institute of Marine Science , CSIC Barcelona Spain
The rapidly warming Arctic opens on to changes in natural aerosol emissions, which have strong feedback effects on the climate system. One of the main primary sources of aerosols in the Arctic is the ocean, emitting sea spray aerosol (SSA). So far, climate models assume that, in a warming Arctic, loss of sea ice and higher wind speeds will lead to a large increase in the SSA emission, but no observational evidence is available to test this assumption. Here we show that SSA production is mainly modulated by the salinity in the freshwater layers covering the surface ocean, arising from melting sea ice. As a result, SSA aerosol fluxes from Arctic water with salinities <30 psu and <27 psu are reduced by factors of 3 and 6, relative to those in average oceanic water (35 psu). Future freshening of the Arctic Ocean - and associated surface salinity gradients - will significantly reduce SSA production, with important implications for the changing Arctic climate.
Arroyo A*¹, Timmermans M-L¹
¹Yale University, New Haven, United States
Quantifying the mechanisms driving seasonal variability of dissolved oxygen (O₂) in the surface Arctic Ocean is crucial to understanding how the seasonal cycle could be evolving or evolve in the future due to the effects of climate change. We model the primary processes that influence seasonal variability of mixed layer O₂ and compare the modeled O₂ variability to O₂ observations from Ice-Tethered Profilers. This allows us to estimate the relative role of each process in driving the annual cycle of mixed-layer O₂. Our findings suggest that contributions to O₂ variability from vertical entrainment at the base of the mixed layer and exchange with the atmosphere are an order of magnitude smaller than contributions to O₂ variability from sea ice melt/growth. Given that sea ice melt/growth is the dominant factor for seasonal variations in mixed layer O₂, the rapid decline of sea-ice extent in recent decades inevitably influences the O₂ seasonal cycle, such that different driving mechanisms emerge in regions that are now ice-free for longer. By isolating the physical drivers, we are able to infer O₂ changes that result from production/respiration – changes which are challenging to measure directly. Our results provide further insight into how declining sea ice modifies Arctic marine primary production, and the consequences to ecosystems.
Session chairs:
Katrine Husum (Norwegian Polar Institute, Norway), Christian März (University of Bonn, Germany), Christine Tømmervik Kollsgård (UiT The Arctic University of Norway, Norway)
Session content:
On a geological time scale, the Arctic Ocean has changed dramatically from greenhouse to icehouse conditions. The marine environment of the Arctic Ocean, and its adjoining margin and shelf seas, gradually evolved into their present form since the termination of the Last Glacial Maximum. Over these ~20,000 years, climate, ecosystems, and the depositional setting developed into their modern expressions. Landforms at the seafloor and the sediment below are archives of environmental fluctuations caused by natural drivers. These morphological and sedimentary archives serve as records of natural baseline values increasing our understanding of the current rapid changes in the Arctic Ocean region. Certain time intervals may also serve as analogues for warmer-than-present conditions and elucidate effects on climate and ecosystems. Talking many of these aspects into account, session C will provide some environmental lessons from the past.
Session chairs:
Bodil Bluhm (UiT The Arctic University of Norway, Norway), Sławomir Kwaśniewski (The Institute of Oceanology of the Polish Academy of Sciences, Poland), Julia Giebichenstein (University of Oslo, Norway)
Session content:
Ecosystems are structured and function in an inextricable relationship between their biota and environment. Environmental conditions drive spatial patterns of biological communities and their function. In the Arctic Ocean, environmental transitions can be gradual or abrupt. They include shifts in water depths from coasts to basins, light regimes from summer to winter, open water to complete sea ice cover, fully marine to estuarine habitats, varying water masses and seafloor properties across fronts and bathymetric features. Resident biota are adapted to the original Arctic environments, and these adaptations act in harmony with multitude of biotic interactions, yet may shift in response to human impact. These corroborating processes influence community structure and function, creating additional complexity which should be understood in order to monitor or manage Arctic ecosystems. Currently, Arctic environments are changing at a rapid pace. The ongoing climate change shows that some of the established links that make up a stable system can alter or even collapse. Thus, the living ocean is a highly complex system, but session B will provide some new aspects contributing to a better understanding.
Session chairs:
Frank Nilsen (UNIS, Norway), Mary-Louise Timmermans (Yale University, USA), Laura Castro de la Guardia (Norwegian Polar Institute, Norway)
Session content:
Some of the excess heat absorbed by the world oceans is transported poleward. At the intersection between the Arctic and sub-Arctic domain, the Polar front forms a fundamental regional feature, and the advected heat causes warming, freshening and changes in the circulation dynamics in the Arctic Ocean itself. This, in turn, affects the Arctic climate and has implications for sea ice, atmosphere, and terrestrial environment. The influence of large-scale patterns (wind forcing, buoyancy loss and large-scale advection) on regional features in the northern Barents Sea and Nansen Basin have been investigated in the Nansen Legacy project. In this session, we aim to integrate these findings into pan-Arctic perspectives and improve our understanding of the ocean-ice-atmosphere system and its drivers in the entire Arctic Ocean.
All Nansen Legacy researchers still actively involved in the project should purchase their travel as they have done previously (follow guidelines at their own institution) and apply for travel reimbursements by their respective partner institutions. The institutions will then send a compiled claim to the project office.
For symposium registration, the project administration will soon send you a booking code by email that will allow you to register for the symposium and book the hotel room through the registration system. Accommodation costs and the participant fee will directly be covered by the Nansen Legacy.