Green tide in MichiganThe marine and fresh waters of the United States are increasingly impacted by the growing environmental problem of harmful algal blooms (HABs), high densities of microscopic algae most noted for their production of potent toxins. HABs are known to occur in all 50 states. HABs can adversely affect human and animal health, and cause significant economic impacts to coastal communities, losses to aquaculture enterprises, and long-term ecosystem changes. While HABs are naturally occurring phenomena, they are increasing in frequency and duration, and geographically expanding due to human-influenced ecosystem changes such as excessive levels of nutrients and extreme weather events. 

IOOS and the Regional Associations (RA) have responded to these impacts by developing a National Harmful Algal Bloom Observing Network (NHABON) implementation strategy, implementing a series of Congressionally mandated HAB pilot projects, funding HAB-related projects via Ocean Technology Transition (OTT) and Coastal and Ocean Modeling Testbed (COMT) grants and via a wide range of RA-originated projects. Total spending was approximately $4M in FY20.

HABs Activities and Projects

Pilot Projects

Harmful Algal Blooms: IOOS Regional Initiatives

Regional Association HAB web pages and data portals

IOOS Association Activities

OTT and COMT HAB related projects

  • OTT - IFCB, ESP, AUV etc.
  • Any HAB related projects - models that support HAB forecasts



  • Caribbean Sargassum 
  • Great Lakes
  • PNW