EPA New England Topics
Red Tide
This page provides links to non-EPA web sites that provide additional information about Red Tide. You will leave the EPA.gov domain and enter another page with more information. EPA cannot attest to the accuracy of information on that non-EPA page. Providing links to a non-EPA Web site is not an endorsement of the other site or the information it contains by EPA or any of its employees. Also, be aware that the privacy protection provided on the EPA.gov domain (see Privacy and Security Notice) may not be available at the external link. 
A "red tide" or "harmful algal bloom" is a natural event caused by rapid growth of microscopic, single-celled algae that makes the ocean looks red or brown, especially in summertime, and especially when rains wash more nutrients into rivers and the sea. Most kinds of algae are harmless plants but some types produce a natural toxin that can contaminate shellfish that eat the algae. Animals or humans who eat the contaminated shellfish can be poisoned. Local fishing areas are usually closed during major red tides to prevent harvest and sales of contaminated shellfish. Local fish advisories tell you when to avoid buying or eating shellfish.
Can't find what you need? Try our A-Z Index.
EPA National
Harmful Algal Blooms (HABs) Gulf of Mexico
General
Massachusetts Division of Marine Fisheries - What is Red Tide?
Massachusetts Department of Public Health - Red Tide Public Health Fact Sheet
NOAA
Centers for Disease Control (CDC), Department of Health and Human Services - About Red Tide
Woods Hole Oceanographic Institute - The Harmful Algae Page
Closure Notices