News that a potent biotoxin has been found in shellfish in Sag Harbor Cove is not reassuring about the general health of the South Fork’s water bodies. This is not an isolated event: A large portion of western Shinnecock Bay was closed in April after the same micro-organism, which causes paralytic shellfish poisoning. Most people who eat clams, oysters, scallops, crabs, or a host of other seafood that can contain the toxin recover after experiencing facial tingling followed by headache, dizziness, nausea, and lack of coordination. In the most extreme cases, paralysis and respiratory failure can cause death.
Paralytic shellfish poisoning, or P.S.P., comes from a type of marine plankton that can cause so-called red or brown tides, which are sometimes observed here. Other times, the plankton spike without there being a visual clue. To help reduce people’s exposure, the State Department of Environmental Conservation takes water samples and examines blue mussels set out specifically to test for the presence of saxitoxin, a general term. D.E.C. staff also routinely check shellfish obtained from wholesale suppliers.
Though historical accounts indicate that shellfish and harmful algae blooms have been around for a long time (the Bible contains an apparent reference), the map of Long Island occurrences suggests a link between higher-density development and the Alexandrium genus of dinoflagellate that causes P.S.P. On Long Island right now, the D.E.C. reports closures of shellfish beds where the toxin has been found in Northport Bay in Huntington, South Oyster Bay in Hempstead, as well as in Southampton and Sag Harbor. Like other algae-population explosions, this one may in part be linked to reduced tidal mixing in protected backwaters, but scientists have linked blooms to stormwater runoff that carries unneeded excess nutrients into the bays.
The emergence of this toxin here should be taken as a stern warning about the health of our marine environment.