Domoic acid, a neurotoxin produced by certain species of the diatom Pseudo‐nitzschia, poses a significant health threat to marine mammals, seabirds and humans. Exposure in humans causes a potentially deadly neurotoxic illness known as amnesic shellfish poisoning. Historically, regular monitoring of domoic acid concentrations in edible shellfish tissues has been an effective strategy to protect human consumers from acute exposure, but understanding the environmental factors that contribute to the accelerated growth and enhanced toxicity of Pseudo-nitzschia cells will greatly improve predictive forecasting and provide a proactive means to minimize exposure when an ecosystem is expected to turn toxic. At present, there are no reliable metrics linking the environmental drivers of domoic acid production and accumulation by natural Pseudo-nitzschia blooms in the coastal waters of California.
This project consisted of a series of controlled laboratory experiments designed to assess the impact of two environmental factors, temperature and ocean acidification (OA) on the growth and production of domoic acid (domoic acid) by diatoms of the Pseudo-nitzschia genus. OA and temperature are both expected to increase in the coming years due to global warming.
Laboratory restrictions due to the coronavirus prevented the full range of proposed studies from being completed, including a novel effort to explore the interactions between temperature and OA. Nonetheless, the experiments, by rigorously mimicking ecological conditions, offered essential new insights into domoic acid production. Contrary to earlier findings, this study found that declining pH due to ocean acidification neither promotes the growth nor enhances the production of domoic acid by Pseudo-nitzschia. The more significant risk for coastal environments — and the resources they support — is ocean warming. The results from these experiments will be provided to three researchers who produce models forecasting harmful algal blooms, providing new biological data that will improve our ability to predict domoic acid risks to marine ecosystems and the fisheries they support.