Harmful Algal Blooms

Microscopic algae support marine food webs, however blooms of some types of these algae can have harmful impacts to the marine environment and human health. Harmful algal blooms or HABs have increased in frequency and intensity off the coast of California over the past several decades. The most common type of HAB in California’s coastal waters is Pseudo-nitzschia, which produces the toxin Domoic Acid.  In 2015, massive bloom of Pseudo-nitzschia closed the west coast Dungeness crab fishery and caused the death of many marine mammals.

The State of California has numerous agencies, including the Department of Public Health and the Office of Environmental Health Hazard Assessment, that monitor for HABs and take action to protect public health. The Ocean Protection Council works with our partner agencies to improve HAB preparedness, monitoring and response in California.

How do we work on harmful algal blooms?

Click on each strategy below to learn more.

  • SOUND POLICY GUIDANCE OPC works with California’s Interagency Harmful Algal Bloom Task Force (HAB Task Force) to better coordinate HAB response and identify policy and management improvements.

    March 2018 HABs Workshop

    OPC and Ocean Science Trust co-hosted a workshop on March 22-23, 2018, in partnership with the HAB Task Force, to discuss how scientific understanding of HABs can be used to inform domoic acid monitoring for seafood safety in California. The discussion also included lessons learned from seafood safety monitoring programs in Oregon, Washington, and the federal jurisdictions.

  • ADVANCING SCIENCE In 2016 OPC funded its nonprofit partner, Ocean Science Trust (OST) to convene a working group of OPC’s Science Advisory Team to explore the science supporting California’s existing HAB and biotoxin monitoring in the marine environment, and provide scientific guidance on how to add capacity and support state needs. OPC has since funded additional research to implement the working group’s recommendations.

    Framing the Scientific Opportunities on HABs and California Fisheries

    The working group developed a short-term scientific guidance report to frame the scientific opportunities on HABs and California fisheries. This report has been used as a guide for funding additional research.

    Improving our Understanding of HABs

    OPC has funded research to improve our understanding of what drives blooms of harmful algae and what drives their production of biotoxins. OPC has also invested in technological advances to enable real-time detection of HABs. See the featured initiatives and projects section below for details.

  • PARTNERSHIP ENGAGEMENT OPC engages with state agencies and external partners to improve HAB preparedness in California.


    OPC staff participate on the steering committee for California HABMAP, which provides information on harmful algal blooms in marine waters to interested stakeholders. For more information, see the HABMAP website.

    HAB Frequently Asked Questions

    In 2016 OPC provided funding for the OPC’s Science Advisory Team to develop a report responding to frequently asked questions about HABs by the fishing and regulatory communities.


Featured Initiatives and Projects

Creating a real-time tracking and early warning system for HABs in California

In November 2019, OPC approved funding to the University of California, San Diego (Scripps) to support the creation of an automated real-time tracking and early warning system for HABs in California. OPC funds will be used to purchase six “imaging-flow cytobots” (IFCBs) which are submersible, high-resolution underwater microscopes able to take real-time images from water flowing through the instrument, while instantaneously transmitting phytoplankton counts and size to scientists’ computers. Data produced by the IFCB network will be fed into C-HARM, an online, publicly available computer model that generates HAB and domoic acid monitoring and prediction. Predictions are generated daily to provide a forecast of where a Pseudo-nitzschia bloom and/or domoic acid event may occur in the next 1-3 days. C-HARM is hosted and available to the public at the NOAA ERDDAP here: https://coastwatch.pfeg.noaa.gov/erddap/griddap/charmForecast0day.graph  Grantees will also produce monthly and special reports to stakeholders, public heath, marine mammal stranding responders, fisheries managers and other users that use this new data.

Understanding the Drivers of Toxic Pseudo-nitzschia Blooms

In 2018, OPC approved funding to the University of Southern California to identify the drivers of the pseudo-nitzschia blooms and toxicity. This research project is using experiments to test the effects of relevant projected levels of nutrients (e.g. nitrate, ammonia, and urea), temperature, and carbonate chemistry on the growth rates and toxin production of Pseudo-nitzschia. These experiments will provide information on how changes in the types of nutrients entering the coastal environment (such as urea or ammonia from sewage), and expected changes in upwelled nutrient supplies due to climate change, may interact with predicted warming and acidification to control the growth and toxin production of Pseudo-nitzschia species.

Advancing Portable Detection Capabilities of HAB Species in California Waters

In 2018, OPC approved a grant to San Jose State University to make genetic detection assays available on a portable instrument for near real-time detection of HABs in the field. Current detection techniques for a number of HAB species rely on visual identification and quantification under a microscope which is labor and time-intensive. This project’s use of genetic detection technology will greatly increase the efficiency of identification for 11 species of HABs.