Project: WHCOHH - Climate forcing of harmful algal blooms and toxicity exposure in the Northeast U.S.

The goal is to understand and predict how climate variability influences harmful algal bloom (HAB) dynamics, toxin exposure to the human population, and impacts on human health.  The proposed studies will incorporate existing knowledge along with new insights on populations of the toxic dinoflagellate Alexandrium fundyense and the diatom Pseudo-nitzschia spp. into models of past, present, and future climate scenarios. The central hypothesis is that climate-induced environmental changes will influence the composition, distribution, and severity of HABs in the Gulf of Maine (GOM) region in ways that are predictable based on response to previous climate forcing. Our prior research has resulted a modeling framework that can predictively characterize A. fundyense populations at large scales in the GOM as well as in small coastal embayments like the Nauset Marsh. Recently, novel in situ observations have demonstrated inconsistencies between the existing model formulation and the characteristics of A. fundyense in the environment, including growth rate, vertical migration, and cyst dynamics and dispersal. Incorporating this new understanding of bloom dynamics into models will be a key step toward improving predictive skill. Application of the models over longer periods will help characterize potential impacts of climate change on the prevalence and intensity of HABs. Hindcast simulations will be compared with climate data records in the GOM to assess model performance and uncertainty, and forecasts run for the range of potential climate forcing scenarios can help quantify future public health risks. Similar predictive modeling capability for GOM blooms of Pseudo-nitzschia spp., an emerging public health risk for the northeastern U.S., remains to be achieved. Developing an analogous modeling framework for Pseudo-nitzschia spp. based on the growing observational record and improved understanding of bloom dynamics will greatly enhance our understanding of this HAB, its impacts on coastal communities, and inform approaches to reducing public health risks.