The New York State Department of Environmental Conservation has temporarily closed multiple waterways on the East End to the harvesting of shellfish and carnivorous gastropods because shellfish there have tested positive for saxitoxin, a neurotoxin that causes paralytic shellfish poisoning, or PSP, high levels of which can cause severe illness and death.
To date, East Hampton Town waterways have not been affected by the neurotoxin, though a sample of water from Three Mile Harbor was tested on Monday.
The D.E.C. first announced temporary shellfish bed closures on April 13. Affected areas in Southampton Town are in the portions of Shinnecock Bay east of the Post Lane Bridge in Quogue and west of a line extending south from the southernmost point of land at Pine Neck Point in East Quogue to the northern terminus of Triton Lane, off Dune Road on the barrier beach south of Pine Neck Point. In Riverhead Town, Meetinghouse Creek and Terry Creek, both tributaries of Flanders Bay, were also closed.
Last Thursday, additional closures were announced in Southampton and Riverhead: all of Flanders Bay and Reeves Bay, including their tributaries, west of a line extending northeast from the northernmost point of land at Goose Creek Point to the southernmost point of land at Simmons Point. In Southold Town, all of Town Creek and Jockey Creek were closed.
Christopher Gobler of Stony Brook University’s School of Marine and Atmospheric Sciences told the East Hampton Town Trustees on Monday that “in all these cases, it’s due to the dinoflagellate known as Alexandrium that makes saxitoxin.” This quantity of PSP-induced closures in one season has not happened since 2012, he said. This is of interest “in that that was another year where we had some anomalously warm weather in the winter.”
At the end of dinoflagellates’ bloom season, they fall into sediment and form cysts, Dr. Gobler said, likening them to seeds. They spend the summer, autumn, and winter there before re-emerging in the spring. To do so, “they have to experience a certain amount of cold temperatures, just like a seed would, but in addition, their cue to re-emerge is water temperature, so when you get warmer than usual winters and springs, you see those temperatures earlier. This emergence at this time isn’t necessarily shocking. In fact, it’s consistent with the trend.”
For the last decade, Dr. Gobler has been monitoring water bodies under trustee jurisdiction. “We have been monitoring East Hampton waters, and specifically have been looking at the head of Three Mile Harbor weekly since, I think, the first week of April,” he said. “And we did see a high count in Three Mile Harbor in early April, but, in happy news, in the last two weeks the levels have been exceedingly low.”
The dinoflagellates could return, “but sometimes these things peak and then don’t come back,” Dr. Gobler said. “Let’s hope for the latter scenario.” Samples were taken in Three Mile Harbor on Monday, with results to be forwarded to the trustees this week. “Again, it’s an unusual year from the perspective of these events,” he said, “but so far, in East Hampton waters — at least in Three Mile Harbor — things are not out of control. The levels were high but have come down. So that may be a good sign that that’s as bad as it’s going to get.”
Filter-feeding shellfish can continue to accumulate saxitoxin as long as it persists at elevated levels, Dr. Gobler said, but it will dissipate once it falls to low levels in the water. Per D.E.C. policy, once a shellfish bed has been closed it will be reopened only following three consecutive weeks of negative samples.
By June, he said, “we know we will no longer see this organism. My prediction is that for this year, because we saw it earlier, it will also vacate our waters earlier, or turn back into those cysts that go to the bottom earlier.”
