August 27th 2013 – Last week, Rust tides caused by the dinoflagellate, Cochlodinium, emerged on eastern Long Island and have since spread east through the Peconic Estuary and Shinnecock Bay. A recent study performed more than two dozen experiments over a four year period in five different Long Island estuaries and found that the loading of nitrogen during significantly increased the growth of Cochlodinium relative to other phytoplankton groups, demonstrating that nitrogen promotes rust tides (1; see figure). In south shore bays, the primary source of nitrogen is septic tanks (2). Recent investigations of the Peconic Estuary found that septic tanks, cesspools, and fertilizers were all important nitrogen sources (3).
September 18 2013 – One month after it began in the far western extreme of the Peconic Estuary, the 2013 Rust Tide has spread clear across the entire Peconic Estuary to Gardiners Bay. On August 17th, the Rust Tide emerged in Meetinghouse Creek and western Flanders Bay. Over the next four weeks, it spread through Great Peconic Bay, Little Peconic Bay, Noyak Bay, and Gardiners Bay where is has been spotted during the last week. Bays and harbors with confirmed Rust Tide during this period include, but are certainly not limited to, Reeves Bay, East Creek, North Sea Harbor, Fish Cove, Sag Harbor, Coecles Harbor, Three Mile Harbor, and Northwest Creek.
The rust tide alga, Cochlodinium, has been notorious on Long Island since it first appeared in a decade ago having been responsible for the deaths of both finfish and shellfish. Last fall, bay scallop densities in the Peconic Estuary declined by ten-fold in some regions during the Rust Tide, causing great disappointment among baymen and lovers of this delicacy. Last month, SCERP reported on the role of nitrogen in promoting these events. In the future, we will describe the role of cysts or seeds in the recurrence of these Tides.