Project 2: Environmental forcing of harmful algal blooms and toxicity exposure

Our goal is to understand and predict how environmental variability influences harmful algal bloom (HAB) dynamics and exposure of human populations to HAB toxins, with implications for human health. We hypothesize that environmental changes will influence the composition, distribution, and severity of HABs in ways that are predictable based on response to previous environmental forcing. Our studies will focus on the dinoflagellate Alexandrium catenella and diatoms of the genus Pseudo-nitzschia, organisms that produce saxitoxin and domoic acid, respectively. Focusing on the Gulf of Maine (GOM), we will construct hindcast simulations into which a revised model of A. catenella model and a to-be-developed model of Pseudo-nitzschia spp. will be incorporated. The A. catenella model revisions will incorporate the latest advances in how cyst germination and loss processes affect bloom timing and development. Hindcasts will be evaluated against observations, documenting fluctuations in abundance of the target species as well as toxicity (toxin accumulation) in coastal shellfish resources. A submodel will be developed to estimate human exposure to these toxins. Discrepancies between the hindcasts and observations will guide iterative model improvement. Once satisfactory agreement has been achieved, the models will be run in forecast mode. We will also assess HAB dynamics in two other model systems: a temperate embayment with Nauset Marsh (NM) and the coastal Arctic. The proposed research will be integrated into the WHCOHH in several ways: (1) what is learned about bloom dynamics in Project 1 will be used to improve HAB models; (2) development of the exposure submodel will be undertaken in collaboration with Project 3; (3) all three projects will participate in the analysis of environmentally-forced variations in HABs and how they affect human exposure to toxins; and (4) results will be communicated through the Community Engagement Core.