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Harmful Algal Blooms threaten human and ecosystem health, and disrupt aquaculture and wild fisheries, tourism, and other resources in marine and freshwater systems.

What are Harmful Algal Blooms (HABs)?

Marine and fresh waters teem with life, much of it microscopic and most of it beneficial and harmless. There are, however, some species of algae and cyanobacteria that cause harm, either through the production of potent toxins or through the accumulated biomass during their “blooms”. Impacts include human and wildlife illness and mortality, ecosystem disruption, and economic losses to coastal communities.

HAB Species

Learn about different toxic or harmful algal species, and the poisoning syndromes they cause


See where harmful algae are distributed in the U.S. and around the world


Discover how harmful algal blooms impact human health and coastal economies, wildlife, ecosystems, and more


Learn about the national and international research programs focused on understanding, managing, and preventing harmful algal blooms


Major programmatic and informational resources regarding harmful algal blooms, as well as fact sheets and hotlines


Programs and activities focused on prediction, control, mitigation, and HAB event response

News and Announcements

EPA new Cyanotoxins Preparedness and Response Toolkit

June 3, 2021

The EPA posted a Cyanotoxins Preparedness and Response Toolkit (CPRT) online. The CPRT will help EPA’s state and tribal partners prepare for potential harmful algal blooms in freshwater bodies and respond to protect public health. Cyanobacterial Harmful Algal Blooms (CyanoHABs) can cause fouling of beaches and shorelines, economic and aesthetic losses, taste and odor problems…

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12th International Conference on Toxic Cyanobacteria

May 24, 2021

The 12th International Conference on Toxic Cyanobacteria (ICTC 12) will be held in Toledo, OH from May 22-27, 2022!  This rendition of ICTC will be a joint effort with the Interdisciplinary Freshwater Harmful Algal Blooms Workshop. As has been done at past ICTCs, submitted papers will also be published in a peer-reviewed journal. We are currently exploring…

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Taxonomic Identification Of Harmful Algae In U.S. Marine Waters

April 16, 2021

Bigelow Laboratory is offering a course on HAB identification for managers and analystsAugust 15-28, 2021. The course will  provide expert training and a certificate of proficiency in harmful algae identification, based on light microscopy, and provide familiarity with alternate identification technologies.    DATES: August 15-28, 2021 (inclusive of travel days and time to ensure on…

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Proceedings of the Workshop on the Socio-economic Effects of Marine and Fresh Water Harmful Algal Blooms in the U.S.

March 23, 2021

The NCCOS Competitive Research Program (CRP) and the U.S. National Office for Harmful Algal Blooms are pleased to release the proceedings of the “Workshop on the Socio-economic Effects of Marine and Fresh Water Harmful Algal Blooms in the United States“, convened in August, 2020. The report documents the workshop’s proceedings and presents recommendations to advance…

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US HAB Early Career Symposium

February 16, 2021

We are pleased to announce the 10.5 US Symposium on Harmful Algae, with the conference theme Emerging Voices and Blooming Careers. This meeting will be held virtually from May 25-27, 2021. Due to the Covid-19 pandemic, the local organizing committee and the US National HAB Committee decided to postpone the 11th US Symposium on Harmful…

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Marine Botany Course at University of Washington

February 16, 2021

Applications are now open for a summer field course in the principles, methods, and applications of marine algal biodiversity studies with a focus on the macroalgae of marine benthic environments. The course will be taught in-person by Dr. Thomas Mumford and Wilson Freshwater at Friday Harbor Labs, University of Washington. For more information on the…

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“Framework for the National Harmful Algal Bloom Observing Network: A Workshop Report” Now Available

January 13, 2021

This framework is a production of a workshop hosted by the National Centers for Coastal Ocean Science (NCCOS) and U.S. Integrated Ocean Observing System (IOOS), with representatives from five Line Offices of the National Oceanic and Atmospheric Administration (NOAA). The report is now available here.

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66th Edition of Harmful Algae News Released

December 23, 2020

A collaboration between the IOC and UNESCO, Harmful Algae News is a free newsletter describing recent updates in the global study of HABs, as well as publicizing networking and training opportunities for professionals. The newsletter can be found here.

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New! Compilation of position listings and opportunities

December 14, 2020

Please visit our position listings to view job postings and opportunities for graduate students and postdocs. If you wish to post a position or opportunity here, please contact

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Funding Opportunity – IOSS Coastal & Ocean Modeling Testbed Project

December 11, 2020

The IOOS FY21 Coastal and Ocean Modeling Testbed grant opportunity has been released, and includes a research objective related to HABs. “Finding efficient approaches to transition ecosystem models (including, but not limited to, ocean acidification, harmful algal bloom (HAB), hypoxia, and pathogens) for incorporation into existing physical modeling frameworks.” For more information about the testbed…

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