Undergraduate Research and Creative Activities Journal

Harmful algal blooms (HABs) are a conglomeration of algal cells that can release toxins that worsen water quality, kill marine life, and ultimately endanger human health. Species of the diatoms in the Pseudo-nitzschia genus, which produce the marine neurotoxin domoic acid, are largely responsible for toxic blooms along the US West Coast. Ocean acidification, increased water temperatures, intensified precipitation unpredictability, and increased water stratification – all caused by global warming – are each linked to increases in domoic acid production in species of Pseudo-nitzschia. In response to HABs, statewide agencies issue advisories against eating certain seafood species and may formally close important commercial and recreational fisheries. These closures can last for months, shortening the fishing season, and costing millions of dollars in revenue or lost days of recreational fishing opportunities. To ease statewide fisheries management and support coastal communities, a review of HAB mitigation strategies and an analysis of four years of predictive data on Pseudo-nitzschia and domoic acid risk from the California Harmful Algae Risk Mapping (C-HARM) model was conducted. Pseudo-nitzschia and domoic acid hotspots were found in geographically retentive areas that are supported in previous studies on HAB dynamics. A new hotspot was identified at the California-Mexico border. Changes in hotspots and HAB development can be explained by large scale atmospheric and oceanic circulation shifts. Recommended mitigation strategies to be further researched and eventually applied are clay flocculation, biological algicides, and allelopathic byproducts. The results of this study underscore the importance of HAB monitoring and modeling and may inform decision-makers on fisheries management.