ECOHAB 2020: Trophic Transfer and Effects of HAB Toxins in Alaskan Marine Food Webs

Investigators: Kathi Lefebvre, Donald Anderson, Chris Whitehead (SEATOR), Dr. Elizabeth Siddon, Steve Kibler, Katherine Hubbard, Kathy Burek-Huntington, Raphaela Stimmelmayr,  Gay Sheffield, Susan Knowles, Dean Stockwell

Institutions: NOAA Northwest Fisheries Science Center, Woods Hole Oceanographic Institution, NOAA Alaska Fisheries Science Center, NOAA National Centers for Coastal Ocean Science, Florida Fish and Wildlife Research Institute, Alaska Veterinary Pathology Services, Sitka Tribe of Alaska, Alaska Sea Grant, University of Alaska Fairbanks, North Slope Borough, United States Geological Survey

As the climate has warmed over the past few decades, Arctic and sub-Arctic waters have experienced dramatic changes. These changes have begun to significantly impact the hydrographic structure and stratification of the Alaskan shelf, as well as the timing and extent of biological production and the biogeographic boundaries of a wide range of species at all trophic levels. Although many organisms may spread into or expand within Arctic waters as a result of the observed warming trend, few present such significant threats to human and ecosystem health as harmful algal bloom (HAB) species, particularly the dinoflagellate Alexandrium catenella and diatoms in the genus Pseudo-nitzschia. This threat is evidenced by observations of the neurotoxins saxitoxin (STX) and domoic acid (DA) in seals, walruses, sea lions, whales, and other marine mammals in Alaskan waters.

The overall goal of this project is to develop quantitative models for the trophic transfer and impacts of HAB toxins in Arctic and Subarctic food webs using empirical data on the abundance of toxin-producing Pseudo-nitzschia and Alexandrium species, corresponding toxin levels in multiple trophic levels, and health assessments and behavioral observation data for marine mammals and fish.

The scientific objectives of the study are to:

1. Identify species composition and map cell densities of toxin-producing Pseudo-nitzschia and Alexandrium species (including Alexandrium cysts) via ships of opportunity and local sampling by Alaskan communities in the Beaufort Sea, Chukchi Sea, Bering Strait, NE/SE Bering Sea, and Gulf of Alaska;
2. Quantify corresponding toxin concentrations (DA & STXs) in phytoplankton, zooplankton, finfish, shellfish and marine mammals sampled during the same time frame from the same regions;
3. Define trophic transfer pathways via stomach content analyses in fish and marine mammals;
4. Document health impacts in naturally-exposed marine mammals and fish in relation to toxin concentrations and bloom densities using behavioral observation reports completed by fishers and subsistence hunters as well as full diagnostic necropsies to determine cause of death including detailed pathology examinations by board certified veterinarians in opportunistically-collected fresh stranded animals; and
5. Use the environmental and observational data generated from objectives 1-4 to develop toxin trophic transfer models to predict the accumulation, biotransformation, and impacts of algal toxins under different bloom scenarios to predict future animal mortality events.