Damaging Brown Tide Re-emerges across entire South Shore of Long Island

Distribution of brown tide cell densities across Great South Bay and Eastern Moriches Bay on July 2nd, 2013

Patchogue Bay, Great South Bay

Stony Brook, NY, October 15, 2013 – An intense and damaging brown tide has re-emerged across most of Great South Bay, Moriches Bay, and Shinnecock Bay.  Monitoring by the Gobler Laboratory based in the Marine Science Research Center in the School of Marine & Atmospheric Sciences at Stony Brook University’s Southampton Campus has revealed that a brown tide that began to develop during September and has intensified this month to nearly 1,000,000 cells per milliliter in central Great South Bay as of October 8. Densities exceeding 200,000 cells per milliliter were also present in western Great South Bay, Moriches Bay, Quantuck Bay, and Shinnecock Bay.

The only regions across Long Island’s South Shore Estuary system that have been spared this scourge have been the ocean inlets, including the New Inlet in Great South Bay which is strongly flushing Bellport Bay and has kept brown tide densities below 20,000 cells per milliliter.  This widespread brown tide comes on the heels of a summer event that occurred during May, June, and July within the same regions.

New inlet in Great South Bay diluting brown tide with ocean water July 2013.

The brown tide alga, Aureococcus anophagefferens, has been notorious on Long Island since it first appeared in 1985 having been responsible for the demise of the largest bay scallop fishery on the US east coast in the Peconic Estuary, the loss of eelgrass across Long Island, and the inhibition of hard clam recovery efforts in Great South Bay.  Densities above 50,000 cells per milliliter can be harmful to marine life, particularly clams.

“The occurrence of a fall brown tide is not uncommon, particularly after a summer with a dense and widespread brown tide,” said Christopher Gobler, Professor of Marine Biology at Stony Brook University’s Southampton campus. “We knew that the summer brown tide would end when the bays heated up above 75 degrees.  We also knew it could return once the bays cooled down in the fall.”

This was unwelcome news for groups like The Nature Conservancy who are working to restore hard clam populations in Great South Bay. Carl LoBue of The Nature Conservancy said, “We know from our experience in 2008-2009 that back to back brown tide blooms not only impacted survival and growth of young clams, it also impacted spawning of adult clams the following season.  We were encouraged in spring because conditions in central Great South Bay looked good into June, so this is disappointing but not surprising, the impacts of pervasive nitrogen pollution have hit almost every bay, harbor, and lake around Long Island this year.”

The occurrence of brown tide in the fall can be problematic for hard clams and other shellfish.  The fall has been identified by scientists as a key period of ‘conditioning’ for clams.  When presented with the right food during the fall, they are more likely to have a successful reproductive season the following spring.  When presented with an extended brown tide, the next generation of clams may fail.  How much this brown tide effects condition may depend on how long it persists.

“In 2011, a fall brown tide lasted through December.  In other years, such as 1999, they have gone into the winter, even persisting under ice coverage of the bay”, said Gobler.

Decades of research at Stony Brook University regarding brown tides have identified excessive nitrogen loading and poor flushing as factors promoting brown tides on Long Island.

© Stony Brook University 2013