State of the Arctic - Land-ocean interactions, benthic and terrestrial ecology
- 09:00 Terrestrial inputs as a key driver of Arctic coastal biogeochemistry, ecology, and contamination
Authors: Amanda Poste ( Norwegian institute for water research ); Maeve McGovern ( Norwegian institute for water research ); Ian Allan ( Norwegian institute for water research ); Michael Arts ( Ryerson University ); Bodil Bluhm ( University of Tromsø ); Katrine Borgå ( University of Oslo ); Pernilla Carlsson ( Norwegian institute for water research ); Nathalie Carrasco ( University of Tromsø ); Guttorm Christensen ( Akvaplan-niva ); Ken Dunton ( University of Texas Marine Sciences Institute ); Anita Evenset ( Akvaplan-niva ); Eirik Aasmo Finne ( University of Oslo ); Dag O. Hessen ( University of Oslo ); Sverre Johansen ( Norwegian University of Life Sciences ); Eva Leu ( Akvaplan-niva ); Connor McKnight ( Norwegian University of Science and Technology ); Paul Renaud ( Akvaplan-niva ); Anders Ruus ( Norwegian institute for water research ); Emelie Skogsberg ( University of Oslo ); Janne E. Søreide ( UNIS ); Øystein Varpe ( UNIS ); Emilie Hernes Vereide ( University of Oslo ); Charlotte Pedersen Ugelstad ( University of Tromsø )
Arctic ecosystems are in transition, with multiple (often inter-related) stressors driving long-term environmental change. Stressors such as climate change (thawing permafrost, melting glaciers, changes in precipitation and runoff patterns) and human activity resulting in land-use changes can lead to altered fluxes of water, nutrients, and contaminants across the land-ocean interface. These changes will have strong effects on coastal ecosystems, highlighting the importance of understanding the transport, transformation and fate of terrestrial inputs, and their effects on local, regional and global biogeochemical cycles, coastal ecology, and contamination of coastal ecosystems.
Despite the biogeochemical and ecological importance of the Arctic coastal zone, key processes and interactions at the land-ocean interface remain relatively poorly understood, perhaps due to the spatial and seasonally dynamic boundaries between terrestrial, freshwater and marine ecosystems. This lack of detailed knowledge makes it difficult to assess the potential impacts of projected future changes in fluxes of freshwater and associated solids and solutes from land to sea.
Here we present new results from the “TerrACE” project, an interdisciplinary project focusing on generating quantitative information about terrestrial inputs to coastal waters in Svalbard, and how these inputs affect coastal biogeochemistry, ecology and accumulation of environmental contaminants in biota. We also present a conceptual meta-ecosystem model for the complex interplay between the terrestrial and coastal Arctic ecosystems.
- 09:30 Increased vascular plant growth leads to a larger and more complex microbial foodweb in high Arctic peatlands
Authors: Kathrin Marina Bender ( UiT ); Mette Marianne Svenning ( UiT ); Yuntao Hu ( University of Vienna ); Andreas Richter ( University of Vienna ); Julia Schückel ( Glycospot ); Susanne Liebner ( GFZ German Research Center for Geosciences ); Alexander Tøsdal Tveit ( UiT )
Herbivorous grazing reduces the ratio of vascular plants to mosses in Arctic peatlands, leading to reductions in the soil carbon and nutrient availability. The link between altered soil conditions and the size and properties of the soil organic carbon degrading (SOC) microbiota is not known. Here we have investigated the plant communities, the soil composition and the microbiota of 20yr fenced exclosures compared to grazed sites using metagenomic, metatranscriptomic, metabolomic and enzymatic methods in combination with plant classification and peat soil chemistry. Our results show that an increased abundance of vascular plants within the fenced sites corresponds to increases in the soil content of the polysaccharides, monosaccharides and amino acids. DNA and RNA quantification showed that a larger and more active microbiota had established in the rhizosphere of the fenced sites. Correspondingly, the gene transcription for polysaccharide degrading enzymes and the potential activity of these enzymes were significantly higher in the fenced sites. While the overall microbial community composition remained the same, we found considerably higher abundances of saprotrophic fungal (Leotiomyceta) transcripts and genes in the fenced sites, confirming that these fungi are able to metabolize a very broad range of plant polymers. Additionally, we saw an increase in the gene transcription of predatory eukaryotes (Collembola), also with a very broad substrate range including both plant and microbial polymers. We conclude that greater densities of vascular plants due to reduced herbivore grazing increases the pools of polysaccharides and dissolved organic nitrogen and carbon. The richer conditions allow the establishment of broad substrate range fungal decomposers of the Leotiomyceta and an overall larger microbial biomass that is food for predatory Collembola. Thus we show that increased vascular plant to moss ratio in high-Arctic peatlands has a positive effect on the SOC decomposing and predatory eukaryotic microbial taxa, leading to a larger microbial biomass and possibly a faster microbial loop.
- 09:45 Effect of seasonal terrestrial run-off on coastal contaminant accumulation in Arctic littoral amphipods
Authors: Emelie Skogsberg ( Institute of Bioscience, University of Oslo ); Øystein Varpe ( The University Center in Svalbard ); Katrine Borgå ( Institute of Bioscience, University of Oslo )
During melt season on Svalbard, rivers and streams bring vast amounts of fresh water, inorganic and organic material from land to the marine coastal environment. Long-range transported contaminants, such as lipophilic poly chlorinated biphenyls (PCBs) and mercury species (Hg), follow the terrestrial run-off to the coastal ecosystems, adhered to organic matter. Taken up in biota, PCB congeners have affinity to be stored in lipid tissues, while Methyl-Hg bioaccumulate in protein-rich tissues. Furthermore, these contaminants biomagnify up the food chain and display a broad range of toxic effects in organisms, thus classifying them as important pollutants to monitor. Today, PCB and Hg emissions are heavily regulated. However, with warmer temperatures due to climate change, coastal areas are expected to receive enhanced riverine inputs, including a longer seasonal window of discharge, leading to an increase in secondary emissions to the marine environment. Previous studies have reported assimilation of terrestrial derived organic matter in lower trophic levels of marine fauna in Arctic estuaries. Thus, by utilizing terrestrial derived carbon, we expect there to be an exposure of bioavailable, long-range transported contaminants via diet.
In the present study, we examine if there are differences in PCBs and Hg level and primary energy source influenced by terrestrial inputs in the intertidal amphipod Gammarus setosus, inhabiting the Adventelva river estuary. Two locations with different proximity to the river outlets were sampled monthly from April to August 2018. Thus, this spread covered both months experiencing no riverine inputs (April), and with impact from terrestrial run-off (May to August). By combining information on stable isotope (SI) and fatty acid (FA) signatures of amphipods and potential diet sources, the utilization of different carbon sources are investigated, including matrixes such as rivers, water, sediments, marine and terrestrial plant material. In addition, their feeding strategy is further considered when combining carbon sources together with lipid content in amphipods, to investigate how they allocate energy during different seasons. Linking lipid dynamics, SI and FA patterns with contamination levels in rivers, sediments and amphipods, we aspire to answer if there is a seasonal signal from the contaminants coming from land entering Arctic marine foods.
- 10:00 Decapod crustaceans in the changing Siberian seas environment: pertinent and new distribution patterns
Authors: Vassily Spiridonov ( Shirshov Institute of Oceanology of Russian Academy of sciences ); Andrey Vedenin ( Shirshov Institute of Oceanology of Russian Academy of Sciences ); Olga Zimina ( Murmansk Marine Biological Institute, Kola Sxience centre of Russian Academy of Science ); Vitaly Syomin ( Institute of Ariz Zones, Southern Science Centre of Russian Academy of Sciences ); Anya Zalota ( Shirshov Institute of Oceanology of Russian Academy of Sciences )
Although moderate in species number, decapod crustaceans are a significant component of the Arctic ecosystems, showing a strong predation effects on benthic communities, providing important trophic links to higher predators, including haddock, cod, polar cod and bearded seal. Their fauna includes species of various biogeographic nature, particularly indicative for high Arctic and for boreal conditions. This makes decapods good sentinels for the ongoing borealization of the Arctic Ocean (Zimina et al., 2015). Several expanding species (snow crab, northern prawn) are of high fishery importance, and prospect for establishing their new commercial stocks needs to be evaluated . We analyzed the recent data on decapod occurrence and distribution collected in several expeditions to the Kara, Laptev and East Siberian Seas between 2007 and 2018. These data were compared to the historical records from museum collection and literature. The Decapoda fauna includes 17 species in the Kara Sea, 17 in the Laptev Sea, and 16 species in the East Siberian Sea. This is about twice lower species number when compared to the Barents and the Chukchi Sea and about the same value as in the semi-landlocked Arctic enclave of the White Sea. The shelf of the Laptev Sea is most poor in decapod species number (11): several Arctic-boreal species extending their distribution to the Arctic either from the Atlantic or the Pacific side are still lacking in that region. On the other hand, the slope of the Laptev Sea, influenced by the inflow of the Atlantic water shows an increase in species richness first of all due to endemic Arctic deep water shrimp species of the genus Bythocaris. An emerging pattern is a broad occurrence of the Arctic-boreal northern prawn (Pandalus borealis) which is nowadays fairly common in the western Kara Sea (influenced by the Barents water) and in the slope and outer shelf area of the Laptev Sea (influenced by the Atlantic water). Another new feature is an intensive expansion of the snow crab, Chionoecetes opilio, introduced in the Barents Sea in the 1980s and now invading the Kara Sea (Zalota et al., 2018; Zalota et al., presentation at this meeting). This species is also native to the Chukchi Sea. Although no indication of the westward expansion of snow crab from the Chukchi Sea have been found since the 1990s when a single specimen has been recorded on the boundary of the between the East Siberian and the Laptev Sea.
- 10:15 Environmental influences on recruitment of benthic invertebrates in the Arctic
Authors: Kirstin Meyer-Kaiser ( Woods Hole Oceanographic Institution ); Melanie Bergmann ( Alfred Wegener Institute ); Thomas Soltwedel ( Alfred Wegener Institute ); Michael Klages ( Alfred Wegener Institute ); Paul Renaud ( Akvaplan-niva ); Andrew Sweetman ( Heriot-Watt University ); Piotr Kuklinski ( Institute of Oceanology Polish Academy of Sciences ); Craig Young ( University of Oregon )
Hard-bottom habitats are uniquely abundant in glacially-influenced polar regions because of the presence of dropstones, i.e. terrestrial stones that were deposited on the seafloor by melting icebergs. These hard substrata contribute to habitat heterogeneity, abundance, and diversity of organisms in the polar benthos. Recruitment is the process by which substrata are colonized by invertebrate larvae, and it is influenced by environmental factors such as temperature and current velocity. Working with German and Norwegian collaborators, I have studied environmental influences on recruitment in the eastern Svalbard waters at depths 7 – 2500 m. Recruitment is much lower in cold, Arctic-influenced fjords than in warm, Atlantic-influenced fjords, and there is an exponential decline in the number of individuals and the number of taxa recruiting at greater depths. A long-term recruitment experiment in the HAUSGARTEN (eastern Fram Strait, 2500 m) revealed only 13 species on experimental panels after 18 years. This species richness is very low compared to background communities on dropstones and a rocky reef in the surrounding area (~60 species). These findings reveal that benthic communities in colder, deeper areas may take decades to develop, making them more vulnerable to disturbance.
Thursday 24th January 2019
09:00 - 10:30