Arctic | Lower Trophic Levels
Planktonic associations in the Northern Bering and Chukchi Seas in the warm period of 2017- 2019 Presenter: Silvana Gonzalez , silvana.gonzalez@noaa.gov, AFSC - NOAA Lisa Eisner , lisa.eisner@noaa.gov, Alaska Fisheries Science Center, NOAA Fisheries David Kimmel , david.kimmel@noaa.gov, Alaska Fisheries Science Center, NOAA Fisheries Michael W Lomas , mlomas@bigelow.org, Bigelow Laboratory for Ocean Sciences, Maine, United States Jens Nielsen , jens.nielsen@noaa.gov, Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington Astrid Schnetzer , aschnet@ncsu.edu Miranda Irby , msirby@ncsu.edu The Northern Bering and Chukchi Seas have been undergoing dramatic oceanographic changes associated with increasing temperatures and shortening of the sea-ice covered season. Changes in oceanographic conditions are expected to have direct and rapid impact on pelagic low-trophic levels (PLTL) including phytoplankton, microzooplankton, and mesozooplankton. Decreasing trends in phytoplankton size and increased abundances of smaller zooplankton of Pacific origin have been reported for the Northern Bering and Chukchi Seas as a response to warming and sea ice loss. Changes in PLTL community composition and size structure can affect trophic interactions, energy pathways and benthic- pelagic coupling of Arctic marine ecosystems. A set of integrated ecosystem surveys were conducted in spring of 2017 and 2018 and in late summer/early fall of 2017 and 2019 in the Northern Bering and Chukchi seas as part of the Arctic Integrated Ecosystem Research Program (Arctic IERP). We used concurrent samples on phytoplankton, microzooplankton, mesozooplankton, and oceanographic conditions from these surveys to understand associations among pelagic communities and the environmental variables that structure them. In general, differences in water column stratification and nutrient availability influenced chlorophyll-a concentrations and size composition, affecting mesozooplankton community structure. As an example, warm water temperature, stratification, and low phytoplankton concentrations recorded in summer of 2019, were associated with higher abundances of small copepods. Our study of spatial patterns in PLTL communities and their environmental drivers over a latitudinal range encompassing regions with different oceanographic conditions provide insight into the structure and function of the pelagic Arctic ecosystem, and increases our understanding of ecosystem responses to further changes in oceanographic conditions. Elizabeth Logerwell , libby.logerwell@noaa.gov, Alaska Fisheries Science Center Russell Hopcroft , rrhopcroft@alaska.edu, University of Alaska Fairbanks, CFOS
Alaska Marine Science Symposium 2023 151
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