Current Research
Modeling the transfer of harmful algal bloom (HAB) toxins in Alaskan marine food chains
Harmful algal blooms (HABs) are historically rare in the Alaskan Arctic because they are too cold to support phytoplankton growth. However, climate change is rapidly warming water temperatures resulting in a more hospitable environment for HAB activity. Recently, there have been multiple dangerous HAB events of the dinoflagellate, Alexandrium catenella, documented in Alaskan Arctic waters. Other algal toxins, such as domoic acid (DA) produced by diatoms of the genus Pseudo-nitzschia, are present, but not in alarming numbers compared to Alexandrium. Alexandrium produce a suite of neurotoxins collectively called saxitoxins (STXs) that block sodium ion channels and suppress central nervous system activity, resulting in paralytic shellfish poisoning (PSP). Algal toxins (STXs and DA) bioaccumulate up the food chain through filter feeding organisms (e.g., clams, copepods, euphausiids) and may pose a threat to the health of key marine resources of coastal Alaskan communities including marine mammals and fish. However, it is currently unknown how algal toxins move throughout Alaskan marine food webs.
I am currently developing models that describe STXs movement in a critical food chain consisting of phytoplankton, benthic invertebrates (clams, snails, and worms), and Pacific walruses (Figure 1). I plan to build additional algal toxin (STXs and DA) trophic transfer models in other marine food chains including bowhead whales and salmon. My overall research objective is to develop models that would be able to predict estimated toxin exposure to critical subsistence resources, including walruses, bowhead whales, and salmon, under multiple future HAB cell densities and toxicities. These models can be used as tools to predict when HAB events are dangerous to native and tribal communities during future scenarios with an altered Arctic climate conducive for frequent HAB events.
Pictures: Skull and crossbones – Clipart library, clams – WDFW, A. catenella cells and cysts – adapted from Natalie Reiner, Pacific walruses on ice; USGS, polychaete; Hans Hillewaert, moon snail; National Aquarium. Background Picture: Collaborators on ECOHAB project - Credit: K. Lefebvre.