ECOHAB: Trophic Transfer & Effects of HAB toxins in Alaskan Marine Food Webs
Problem & Rationale:
There is clear evidence that multiple harmful algal bloom (HAB) toxins are present in Arctic and Subarctic food webs at levels of concern. Two of the most common toxin types include domoic acid (DA; produced by Pseudo-nitzschia species) and Paralytic Shellfish Toxins (PSTs; produced by Alexandrium species). The risks of these toxins include human illness and death associated with seafood consumption as well as health impacts to marine wildlife at multiple trophic levels. Trophic transfer pathways are partially understood or can be inferred in some cases, but there is a critical knowledge gap regarding the relationships between HAB cell/cyst densities, toxin accumulation in vector species, and toxin loads that cause illness and/or death in marine wildlife. Many commercially valuable shellfish and finfish are impacted by these toxins, as well as subsistence-harvested marine mammals. Not only are fish and marine mammals used for human consumption, but many of these species are threatened or endangered themselves. In order to effectively manage these important wildlife populations, it is imperative to understand the relationships between bloom densities and corresponding toxin production, accumulation, biotransformation and health impacts in marine wildlife at all trophic levels. ECOHAB Priority: Determining the trophic transfer of toxins within food webs and the impacts of toxins on individual organisms and food webs.
Scientific Objectives- The objectives of the proposed study are to: 1) quantify toxic algal cell densities (Pseudo-nitzschia and Alexandrium), 2) quantify corresponding toxin concentrations (DA and PSTs/STXs) in phytoplankton, zooplankton, shellfish, finfish and marine mammals, 3) define trophic transfer pathways via stomach content analyses in fish and marine mammals, 4) document health impacts in marine mammals and fish in relation to toxin concentrations and bloom densities using behavioral observation reports by fishers and subsistence hunters as well as detailed pathology examinations in opportunistically-collected fresh stranded marine mammals, and 5) use the environmental and observational data generated from objectives 1-4 to develop toxin - trophic transfer models for algal toxin accumulation and impact in specific food webs under multiple bloom scenarios and to predict future animal mortality events.
Work to be completed- The objectives for the proposed Alaska-based regional ECOHAB food web study will be addressed in all oceanic waters bordering Alaska including the Beaufort and Chukchi Seas, NE and SE Bering Sea and the Gulf of Alaska (GOA) via sample collection on cruises of opportunity including NSF-funded and NOAA’s Ecosystem Monitoring and Assessment yearly Bering Arctic Subarctic Integrated Surveys (BASIS) cruises. Coastal regions in Barrow, Nome, Bristol Bay, St. Lawrence and Aleutian Islands, Kachemak Bay, Prince William Sound, Sitka and SE GOA will also be included via established regional HAB monitoring programs and newly-developed community-based sampling by Alaska Native Villages. Marine mammals will be obtained via the AK Marine Mammal Stranding Network, US Fish & Wildlife, AK Fish & Game and AK subsistence harvest communities. All data will be compiled into a central database and used for the development of models for quantifying toxin exposure and effects in Alaskan food webs. This NRC RAP opportunity is for a modeler to accomplish Objective #5 (above): use the environmental and observational data generated from objectives 1-4 to develop toxin - trophic transfer models for algal toxin accumulation and impact in specific food webs under multiple bloom scenarios and to predict future animal mortality events.