Despite being among the most remote ecosystems on earth, Arctic and Antarctic are facing severe impacts from climate change and other anthropogenic disturbances. Such perturbations and stressors include ocean warming and acidification, altered nutrient input and oxygen content, sea ice loss and freshening as well as various types of pollution and harvesting, all environmental factors that could impact species distributions (such as poleward range shifts), as well as phenology, and demography which again could impact the overall ecosystem functioning and services. However, little is known about how polar species – and not at least the complex ecosystem dynamics – may respond to these key drivers/stressors. For instance, how will different environmental stressors, e.g. long vs. short term perturbations impact polar ecosystem(s)? Are some species more vulnerable than others? There is a great concern that stressors can interact synergistically to magnify each other effects on polar species, triggering the cascading effects on the entire polar food web. Furthermore, the strength and dynamics of these drivers/stressors across the spatial and temporal scales (e.g. seasonality vs. interannual variation) may result in a huge difference in ecological effects. Defining the current and past magnitude, variability and drivers of these stressors would be essential, and not at least how they impact complex polar ecosystem dynamics (at the species, population and individual level) will provide unique knowledge and understanding of the future polar ecosystems under rapidly changing environments. In this special session, we encourage contributions focusing on determining the key abiotic and biotic drivers/stressors – including ocean warming and acidification, altered nutrient input and oxygen content, sea ice loss and freshening as well as various types of pollution and harvesting – in the polar ecosystems both in terms of seasonality and interannual variability. Furthermore, studies on how these drivers interact and affect the polar species and ecosystem(s), from short-term (e.g. phenotypic plasticity) to long-term (evolutionary) responses such as alterations in population genetic/genomic structure, demography, as well as changes in trophic interactions and food web structure are welcome. Key topics of this special session are: Effects of ocean warming, marine heatwaves, acidification, pollution, and freshening on polar phytoplankton, invertebrates, fish, birds, and mammals across seasons. Effects of sea ice changes on the polar community structure and function. The transfer of the legacy and emerging contaminants in the polar food web and the ecological consequences. Atlantification of Arctic community under multiple stressors: changes in competition, niche partitioning and food web structure and dynamics. Phenotypic plasticity, transgenerational plasticity and genetic adaptations of polar species to key stressors/drivers. Impact of climate change and harvesting on population genetic/genomic structure and demography. The mismatch of different trophic levels caused by changes in the phenology. Advancements in developing new methods to assess changes in polar ecosystems: past, present, and future. Polar night ecology
Lead Organizer: Khuong Dinh, University of Oslo, Norway (van.k.dinh@ibv.uio.no)
Co-organizers:
Sissel Jentoft, University of Oslo, Norway (sissel.jentoft@ibv.uio.no)
Joël Durant, University of Oslo, Norway (joel.durant@ibv.uio.no)
Chierici Melissa, Institute of Marine Research, Norway (melissa.chierici@hi.no)
Presentations
03:00 PM
Circumpolar impacts of climate change and anthropogenic stressors on polar cod (Boreogadus saida) and its ecosystem: a review (4872)
Primary Presenter: Caroline Bouchard, Greenland Institute of Natural Resources (cabo@natur.gl)
Polar cod is the most abundant forage fish in the Arctic Ocean. We review polar cod habitats, distribution, ecology, and physiology to assess how climate change and other anthropogenic stressors affect this key species. This review identifies vulnerabilities for different life stages across the whole distribution range of polar cod. We explore the impact of environmental (abiotic and biotic) and anthropogenic stressors on polar cod and identify knowledge gaps constraining predictions. Epipelagic eggs and larvae are more vulnerable to climate change and stressors than adults. Increasing water temperature, sea ice decline, change in freshwater input, acidification, changing prey field, increased competition, new predators, and pollution are the principal stressors that will affect polar cod populations. Detrimental effects are likely to be stronger in regions with advection of warmer Atlantic and Pacific waters. In contrast, polar cod may benefit from ocean warming in colder areas of the High Arctic. The risk from fisheries is moderate and primarily limited to bycatch. Overall, a decrease in suitable habitat and an associated decline in total polar cod biomass is predicted. In most Arctic seas, the relative abundance of polar cod within the fish community will likely fluctuate between cold and warm periods. Regional management measures that recognize the critical role of polar cod are required to ensure that increased anthropogenic activities do not exacerbate the impacts of climate change on Arctic marine ecosystems. Ultimately, mitigation of habitat loss for polar cod will only be achieved through a global reduction in carbon emissions.
03:15 PM
Identification of multiple chromosomal inversions and fusions in a keystone Arctic species with high geneflow (7501)
Primary Presenter: Siv Nam Khang Hoff, University of Oslo (s.n.k.hoff@ibv.uio.no)
There is increasing awareness that anthropogenic stressors, including global warming and harvesting, impact the complex ecosystem dynamics of the Arctic Ocean. How a species responds to these stressors, however, will rely on its genomic architecture(s) and adaptive capacity. Here, we report on the genomic composition and diversity of the keystone fish species polar cod (Boreogadus saida), across parts of its distributional range. Preliminary analyses of whole genome sequencing data across the northern Barents Sea and adjacent regions including Icelandic and Russian waters, uncover high geneflow and little population structuring. Interestingly, despite genomic intermixing, we identify several chromosomal inversions and fusions, displaying high degree of genetic divergence and strong signals of selection, and thus, indicative of signals of local adaptation. Additionally, we discover a large sex determining region on chromosome 5, harbouring the gene FOXJ3 involved in male gonad development. Our results provide new and valuable insights into the genomic architecture(s) and diversity of an ecological important species in a rapidly changing environment. The discovery of multiple chromosomal inversions as well as chromosomal fusions, demonstrates their importance for facilitating local adaptation under extreme environmental conditions, in an otherwise panmictic population with high gene flow.
03:30 PM
EPIBENTHIC BIODIVERSITY, COMMUNITY ASSEMBLY, AND FOOD WEB STRUCTURE ACROSS AN ARCTIC SEASCAPE (6439)
Primary Presenter: Marie Nordström, Abo Akademi University (marie.nordstrom@abo.fi)
Environmental gradients shaping communities and trophic structure are likely to influence ecosystem functioning with implications for stability. For ecosystems characterized by rapid changes, such as those induced by climate change in the Arctic Ocean, it is therefore imperative that we form a thorough understanding of how food webs currently are structured. In this work, we explore the biodiversity of benthic communities in under-studied Northeast Greenland waters. More specifically, we present both taxonomic and trait-based diversity of epifaunal invertebrates, as well as estimates of food web structure for the benthic communities across a high-Arctic seascape, encompassing fjord, shelf, shelf-break, and upper-slope habitats. Our approach allows us to better understand community assembly by examining how species relatedness, traits, and the environment contribute to structuring the communities. Despite a habitat-specific community structure, reflected in the trait-based estimates of diversity, the epibenthic invertebrate food web characterized using stable isotopes of carbon and nitrogen did not show any consistent spatial trend. Instead, there was high overlap among consumer assemblages, which would suggest that, even with changes in consumer composition and assumed availability of different food sources, food web structure (as depicted in isotope space) remains inert across the different habitats. Finally, we present the first food web ‘metaweb’ for the region, and a first assessment of network structure across the seascape.
03:45 PM
Spatial and annual trends in the lipid dynamics of Arctic snow crab during and following a recent Bering Sea heat wave (6817)
Primary Presenter: Louise Copeman, National Oceanic and Atmospheric Administration (louise.copeman@noaa.gov)
A marine heat wave occurred in the eastern Bering Sea during 2018 and 2019. Since then, ten billion snow crab have vanished from the region and the fishery was declared overfished in 2021 and subsequently closed in 2022. Over the last three decades, the geographic range of snow crab (Chionoecetes opilio) in the eastern Bering Sea has contracted to the north in association with warming near-bottom temperatures and reduction of the cold pool, a < 2 oC body of bottom water that forms in the spring during sea ice melt. During years of extensive sea ice formation, the cold pool extends to the southeastern middle shelf (~56oN), while during years of low sea ice formation, the cold pool contracts to the northwest (~60oN). In recent heat wave years, the cold pool was completely absent from the eastern Bering Sea shelf. The causal mechanisms that link declining Bering Sea snow crab populations to shrinking cold pool extent are not fully understood, but include increased predation, higher levels of disease, direct thermal stress, and changes in food quantity and quality. Here we present data that support reduced nutritional condition in large juvenile snow crab (prior to their terminal molt) collected in the southeastern Bering Sea during the 2019 heatwave. We compare region-specific (southeastern and northern Bering Sea) crab condition in the 2019 heatwave year to two subsequent years (2021 and 2022). Specifically, we have used moisture content and fatty acid concentrations in crab hepatopancreas tissue as a new and rapid condition metric. Finally, we present specific fatty acid trophic markers that link decreasing crab energetic condition in southern regions during 2019 to a higher level of carnivory (18:1n-9/18:1n-7) and a decrease in diatom-sourced fatty acids (16:1n-7/16:0) fluxing to the benthos.
04:00 PM
ASSESSING THE INFLUENCE OF STORMS ON SEA ICE, SNOW, AND ADÉLIE PENGUINS ALONG THE WEST ANTARCTIC PENINSULA (7311)
Primary Presenter: Mary Stack, University of Virginia (mary.elizabeth.stack@gmail.com)
Seasonal sea ice fluctuations influence population dynamics across the West Antarctic Peninsula (wAP), a region that has experienced some of the most rapid sea ice declines anywhere along the continent. In the northern region, the ice-obligate Adélie penguins (P. adeliae) have declined by approximately 90% over the last several decades whereas southern colonies have not. Sea-ice and snow are important factors for Adélie penguin population dynamics and can influence breeding habitat, breeding success, and fledging weight. This study investigates the disturbances of storms across temporal and spatial scales as a driver of the declining Adélie penguin population. Potential impacts from storms are investigated both indirectly (sea ice and snow) and directly (breeding success and fledging weight). Understanding the drivers of population decline will help predict how southern colonies may respond as the ecosystem shifts from polar to subpolar. To date, this study examined the temporal relationship of sea-ice indices (advance, retreat, and duration) with storm intensity and frequency from 1979 to 2016 along the wAP. Storm frequency showed a statistically significant increase over time for the austral Fall season. Sea-ice advance is shifting later in many areas, predominantly coastal zones. These coastal zones experience a delayed advancement when the mean storm intensity is increased. Future work incorporating the penguin metrics will use mixed models to identify the physical drivers influencing Adélie breeding success and fledging weight.
04:15 PM
Near real-time assessment of Southern Ocean ecosystem health through animal-tracking and remote-sensing of seabird populations (5788)
Primary Presenter: Céline Le Bohec, Centre national de la recherche scientifique (CNRS) (celine.le-bohec@cnrs.fr)
Assessing the ongoing and future adaptive capacities of populations to cope with global changes challenge our best ecological monitoring tools, even more so for remote ecosystems like Polar Regions. Polar Life Observatories aim to fill such a gap by setting long-term electronic and telemetric monitoring of key polar seabirds together with systematic sampling of biological material during tagging. Doing so, we could unravel the ecological and evolutionary processes shaping populations and quantify the trend and health of their ecosystems. Our multidisciplinary and integrative collaborative network aims to measure the individual and population responses to environmental constraints by examining the complex selective forces at play both at sea and on land. To delineate their adaptive potential, we deploy state-of-the-art methods to quantify genetic and gene expression diversity together with epigenetic processes. By integrating these mechanisms at all levels of diversity, we develop predictive models for the evolutionary responses of populations to environmental changes. Altogether our near real-time marine ecosystem remote sensing could be expanded to a circumAntarctic smart Life Observatories network enabling for the first time population conservation and ecosystem management action plans with detail and current data in situ.
SS007A Defining Drivers and Impact of Climatic Change and Other Anthropogenetic Stressors on Polar Ecosystems: for Long-Term Assessment of Resilience, Functionality and Services
Description
Time: 3:00 PM
Date: 8/6/2023
Room: Sala Santa Catalina