"Red tide" is a common term used to refer to blooms of species of microscopic algae that discolor the water red when present in high concentrations. The impacts and toxicity of a red tide depend on the algal species that causes it, which can vary with geographic region. Some species of algae can form harmful blooms but do not discolor the water. Algal blooms that have adverse impacts on human health or marine environments are collectively referred to as harmful algal blooms (HABs). Harmful algal blooms are a common feature in coastal ecosystems and one of the most complex phenomena challenging managers of aquatic and coastal ecosystems.
For more information about NOAA's harmful algal bloom research, HAB species, and HAB toxins and their impacts on humans, marine environments, and coastal economies, visit:
NOAA Webpage on Alexandrium Research in the Gulf of Maine
This page gives an overview of past and present research on Alexandrium in the Gulf of Maine.
NOAA and other Agency Projects related to Alexandrium in the Northeastern U.S. (pdf, 61 kb)
This table lists the funding agency, principal investigator, institution and title of projects related to Alexandrium in the Northeastern U.S.
NOAA Harmful Algal Bloom Event Response Program
This page describes the design of the NOAA HAB Event Response Program to support coastal managers faced with responding to unusual or unexpected HABs..
Harmful Algal Bloom and Hypoxia Research and Control Act
This page describes the Harmful Algal Bloom and Hypoxia Research and Control Act of 2004, which reaffirms and expands the mandate for NOAA to advance the scientific understanding and control of HABs.
NOAA's Marine Biotoxin Program
This Web site contains information on NOAA’s Marine Biotoxin Program established in 1992 following the U.S. National Plan for Marine Biotoxins and Harmful Algae.
NOAA's Northwest Fisheries Science Center HABS and Marine Biotoxin Pages
This Northwest Fisheries Science Center Web site provides information on West Coast HABs and marine biotoxins.
NOAA National Sea Grant Digital HAB Library
This library contains digital copies of research into harmful algal blooms funded through NOAA's National Sea Grant Program
Woods Hole Oceanographic Institution's Human Illness Associated with Harmful Algae Pages
This Woods Hole Oceanographic Institution Web site provides information on the different human illnesses associated with Harmful Algal Blooms.
Economic Impacts of HABS in The United States
This webpage describes the economic impacts of harmful algal blooms in the United States.