Chesapeake Bay Coastal Bays Rivers and Streams Watersheds
Maryland Department of Natural Resources

Brown Tide
Aureococcus anaphogefferens

The first bloom of this species – also known as a ‘Brown Tide Bloom’ because it turns the water a coffee color -- was identified in Narragansett Bay, Rhode Island in 1985.  Since then it has been identified progressively farther south with Maryland currently its furthest southern extent of Category 3 blooms. While there are no known human impacts from Brown Tide, Brown tide blooms can have serious

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impacts on shellfish fisheries as well as bay grasses.  Learn more about Brown Tide blooms and their documented environmental impacts.

Aureococcus was first identified in Maryland’s Coastal Bays during 1998.  However,  subsequent analysis of pigment data, conducted by the University of MD, Horn Point Laboratory, has identified the historic presence of Aureococcus in the Coastal Bays in 1993, 1994 and 1995 (the only years these data were available from the National Park Service).  The Maryland Department of Natural Resources continues to conduct Brown Tide monitoring in the Coastal Bays between May and July each year.  Data collected since 1999 are available.  Additional impact studies are also being conducted related to hard clams.

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