Algal Identification


Harmful Algal Blooms

Harmful Algal Blooms in Maryland

Brown Tide Distribution

Where has Aureococcus anophagefferens been found?

Prior to 1999, brown tide blooms had only been found from Narragansett Bay, Rhode Island to Barnegat Bay, New Jersey. The Delaware Inland Bays program tested for it in summer 1998, and found Aureococcus in Little Assawoman Bay. Subsequent sampling revealed Aureococcus in Assawoman Bay, MD. In spite of very low counts, the occurrence of Aureococcus in Little Assawoman and Assawoman Bays was significant because:

  • Aureococcus had never been found in this area before;
  • the coastal bays may provide an optimal environment for blooms; and
  • blooms could have ecosystem-wide impacts if damage to eelgrass and bivalve populations is substantial.


In response to these findings, the Maryland Department of Natural Resources began monitoring the distribution of Aureococcus in Maryland’s coastal bays in 1999 at 15 stations during the spring and early summer. 

Since that time Brown Tide has been found in all of the Maryland Coastal Bays. Maryland DNR continues to monitor Brown Tide blooms in the coastal bays each year.

Click on a date below to view Brown Tide Distribution for that year.


For more information contact Cathy Wazniak (410-260-8638) Maryland Department of Natural Resources Tidewater Ecosystem Assessment Division