Arctic | Ecosystem Perspectives DOCTORATE ORAL PRESENTATION Alexandrium catenella cell distribution and dynamics during a massive 2022 Bering Strait bloom
Presenter: Evie Fachon , efachon@whoi.edu, Arctic Research Consortium of the United States Eric Muhlbach , eric.muhlbach@myfwc.com, Florida Fish and Wildlife Conservation Commission Robert Pickart , rpickart@whoi.edu, Woods Hole Oceanographic Institute Peigen Lin , NOAA Northwest Fisheries Science Center Michael Brosnahan , mbrosnahan@whoi.edu, Woods Hole Oceanographic Insitution Mrun Pathare , mpathare@whoi.edu, Woods Hole Oceanographic Insitution Kali Horn , khorn@whoi.edu, Woods Hole Oceanographic Insitution Kathi Lefebvre , NOAA Northwest Fisheries Science Center Nate Spada , nspada@whoi.edu, Woods Hole Oceanographic Insitution Donald Anderson , danderson@whoi.edu, Woods Hole Oceanographic Institution
Rapidly changing conditions in the Pacific Arctic region have raised concerns about the potential for harmful algal bloom (HAB) events and their effects on ecosystems and coastal communities. These concerns were realized this past summer, when exceptionally large and dense populations of the toxic dinoflagellate Alexandrium catenella were detected in the waters of the Bering Strait region during a 49-day research cruise. The bloom was first identified near St. Lawrence Island in mid-July, and high cell concentrations ultimately extended through the Bering Strait, into Kotzebue Sound, and onto the central Chukchi Shelf, at times exceeding 100,000 cells/L. Underway phytoplankton imagery was collected by an Imaging FlowCytobot, allowing real-time identification of these harmful algal cells and prompting intensified sampling in bloom regions. At bloom locations, large volume samples were collected using net tows and the shipboard underway seawater system, and samples are being processed for species identification and total STX content. Our initial results indicate that the 2022 bloom originated in the western waters of the Northern Bering Sea and was transported into and through the Strait to Kotzebue Sound and beyond. There is no evidence that two previously characterized A. catenella cyst beds in the Ledyard Bay and Utqiaġvik regions contributed to the event, likely because near bottom temperatures were too cold. In this presentation, we will report how key properties of the bloom (cell density, cell size, % community composition Alexandrium) varied over space and time during the sampling period. These details can provide additional insights into bloom progression, origins, connectivity, and other conditions surrounding this unprecedented event.
Alaska Marine Science Symposium 2023 84
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