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Marine Biotoxin Monitoring Program

Map of Long Island monitoring sites
Long Island biotoxin monitoring sites.

Searching for Biotoxins in Long Island Waters

Every year, beginning in the spring and continuing through the fall, the Shellfisheries Bureau conducts an extensive Marine Biotoxin Monitoring program across Long Island. We search for the presence of Alexandrium cells in the water column as well as the presence of saxitoxin in molluscan shellfish. Alexandrium is a microscopic, photosynthetic dinoflagellate. It is widely distributed along the coast and lives in the upper layer of the ocean. This dinoflagellate produces saxitoxin, the neuromuscular toxin that causes Paralytic Shellfish Poisoning (PSP). The toxin accumulates in the tissues of any animals that eat the dinoflagellate and may be present in high concentrations in shellfish. Eating shellfish that may have consumed Alexandrium may pose a health threat for animals and humans.

Monitoring Technique

A staff deploying a biotoxin Monitoring bouy into the sea
Shellfisheries staff deploying a biotoxin monitoring bouy.

We have deployed mesh bags of blue mussels that are suspended in the water at sites around Long Island. The map on this page shows the location of our monitoring sites. Mussels are collected from the bags weekly and are examined for the presence of saxitoxin. In addition, samples of locally harvested clams and oysters and samples of shellfish from wholesale markets are examined for the presence of saxitoxin. When mussels from a site test positive, the surrounding area is immediately closed to the harvest of molluscan shellfish and won't reopen for harvest until three consecutive tests over a two week period come back negative for the toxin. Closures resulting from the presence of toxins are reported on the Temporary Shellfish Closures page.

We use blue mussels as our test organism because they concentrate the toxin faster than other species of shellfish. When we collect mussels at each site, we also collect a plankton sample from the water and look for the presence of Alexandrium at the site.

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