Present and future climatic drivers of domoic acid toxicity in coastal ecosystems of California

Chains of the neurotoxin-producing diatom, Pseudo-nitzschia australis isolated from northern California coastal waters during the massive toxic bloom of 2015, and still blooming in lesser abundances off California in 2018.    CREDIT: (C. Wingert photo, Cochlan Phytoplankton Ecophysiology Lab, San Francisco State University)

Domoic acid, a neurotoxin produced by certain species of the diatom, Pseudo‐nitzschia, poses a significant health threat to marine mammals, seabirds, and humans via transfer of the toxin through the marine food web. 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 will test the hypothesis that increased accumulation of domoic acid‐producing cells is driven by the levels of two environmental stressors associated with the future ocean: warmer temperatures and more acidic (lower pH) ocean conditions. While previous studies have focused on examining single environmental stressors, this project seeks to understand multiple environmental stressors and their interactions on the production of domoic acid.

The insights from this study will include an understanding of which environmental parameters are valuable predictors of potential domoic acid exposure in coastal ecosystems, and will enable modelers to establish the critical windows of opportunity for enhanced growth and particulate domoic acid production under climate change scenarios, and thus characterize the degree of risk of domoic acid toxicity to marine ecosystems, crucial fisheries and human health.

Co-principal Investigators