Future changing environmental conditions may lead to more harmful algal blooms

Harmful algal blooms (HABs) of several toxic diatom species within the genus Pseudo-nitzschia annually cause significant damage to ecosystems and economies along the California coast. Pseudo-nitzschia can produce the neurotoxin domoic acid, which can cause fish kills, marine mammal sickness, and cause severe health issues in humans who consume contaminated seafood. Recent evidence suggests that increased nutrient availability due to either anthropogenic pollution or climate-driven shifts in upwelling patterns can combine with other individual factors (e.g., temperature and carbonate chemistry) to significantly increase the toxicity of these blooms. Little is known about how projected future changes of these combined factors will affect HAB frequency in California. University of Southern California (USC) Sea Grant funded a project to conduct multi-stressor studies with Pseudo-nitzschia cultures isolated from California waters to predict how future environmental conditions may influence damaging, toxic blooms.

Key Results:

  • Experiments simulating coastal upwelling conditions (i.e., cooler temps, increased nutrients) and marine heatwave conditions (i.e., warmer temps, decreased nutrients) promote similar growth rates in Pseudo-nitzschia australis, but only upwelling conditions produced domoic acid toxicity
  • Research is designed to fill data gaps outlined in the 2016 California Ocean Science Trust HAB and California Fisheries Report


Project Impacts & Application:

  • Presented at the Association for the Sciences of Limnology and Oceanography Meeting, the U.S. HAB Symposium, the USC Marine Biology and Biological Oceanography Student Seminar Series, and the Ocean Sciences Meeting
  • Invited to give a webinar at C-CAN (the California Coastal Acidification Network) 


Principal Investigators:

  • David Hutchins, Ph.D., University of Southern California  
  • Feixue Fu, Ph.D., University of Southern California


California Ocean Protection Council, 2018-2021

Additional Info and Publications:

  • Kelly KJ, Fu F-X, Jiang X, Li H, Xu D, Yang N, DeMers MA, Kling JD, Gao K, YeN and Hutchins DA (2021). Interactions Between Ultraviolet B Radiation, Warming, and Changing Nitrogen Source May Reduce the Accumulation of Toxic Pseudo-nitzschia multiseries Biomass in FutureCoastal Oceans. Front. Mar. Sci. 8:664302. doi: 10.3389/fmars.2021.664302

Access our Publications Database to view publications from this project or other related topics

Pseudo-nitzschia under the microscope.

Pseudo-nitzschia under the microscope