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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

Proceedings of the the Workshop on the Socio-economic Effects of Harmful Algal Blooms in the United States

March 18, 2022

The proceedings document describing the Workshop on the Socio-economic Effects of Harmful Algal Blooms in the United States is now available here. The report documents the proceedings of a 2020 workshop convened by NOAA NCCOS and the U.S. National Office for HABs, and presents recommendations to advance an assessment framework and a national research agenda…

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HARMFUL ALGAE NEWS No. 70 now available

February 22, 2022

IOC-UNESCO Harmful Algae News no.70 is now available online. Be sure to check it out HERE.

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11th U.S. Symposium on Harmful Algae – Register now!

November 23, 2021

We are pleased to announce that the 11th U.S. Symposium on Harmful Algae will be held on October 23-28, 2022, in Albany, New York, at the Hilton Albany.  REGISTRATION IS NOW OPEN! Poster abstracts will continue to be accepted as space permits through July 15, 2022 (11:59 PST). Visit our conference website for details regarding…

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19th ICHA – Abstract book available!

October 4, 2021

Thanks to the organizers of this virtual event! The abstracts are available HERE.  Conference proceedings will be posted when available.

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OHHABS Summary Report Available

October 4, 2021

The CDC published the 2019 US summary on harmful algal bloom (HAB) events and associated human or animal illnesses through the One Health Harmful Algal Bloom System (OHHABS). One Health is a multi-sectoral approach that involves engagement across disciplines including public health, animal health, and environmental health. Using the One Health approach, CDC collects data…

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HABs and Ocean Acidification Report Published

August 12, 2021

The workshop report associated with NOAA NCCOS’s August 2020 workshop on interactions between HABs and ocean acidification is now available. To read the report, please click here.

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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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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

Thank you for attending the 10.5 US Symposium on Harmful Algae, with the conference theme Emerging Voices and Blooming Careers. This meeting was held virtually from May 25-27, 2021.  You can access the meeting website here  and the conference program here.

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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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