Wednesday, May 07, 2008

Lethal Toxin Forces New York to Close Some Long Island Sound Shellfish Beds

What to make of this? For the second time since 2006, New York State has closed shellfish beds on Long Island's north shore because of a marine biotoxin, called saxitoxin, that causes paralytic shellfish poisoning in humans. Until two years ago, saxitoxin had apparently never been seen before in Long Island Sound. Here's the state's advisory:

The New York State Department of Environmental Conservation (DEC) today announced that shellfish harvesting in certain bays in Long Island Sound have been temporarily closed due to the detection of a marine biotoxin.

The closure impacts approximately 2,000 acres, covering all the shellfishing lands in Northport Bay, Centerport Harbor and Duck Island Harbor that lie east of a line extending from the southernmost point of West Beach (also known as Sand City Beach) to the northeast corner of the beach pavilion at the Town of Huntington’s Crescent Beach, located on the southeastern shore of Huntington Bay. These areas are home to clams, mussels and oysters.

All shellfishing in these lands is prohibited till further notice in an effort to protect public health.

The precaution was taken after DEC determined that shellfish samples collected from Northport Harbor tested positive for saxitoxin, a marine biotoxin that causes paralytic shellfish poisoning (PSP). In 2006, DEC implemented its first-ever closure of shellfish lands due to the detection of biotoxins in shellfish in Northport Harbor.

DEC will re-open areas as soon as possible based on the results of laboratory analyses of shellfish and water samples that will be collected during the week. A taped message advising harvesters of the status of shellfish areas may be heard at (631) 444-0480. The message will be updated during the course of the temporary closure.

Saxitoxin and paralytic shellfish poisoning sound bad. From Wikipedia:

Saxitoxin (STX) is a cyanotoxin found in marine dinoflagellates (algae). It is a neurotoxin that is a selective sodium channel blocker. The United States military isolated saxitoxin and assigned it the chemical weapon designation TZ. It is almost unique among toxins in that it acts very quickly, in a matter of minutes. The median lethal concentration (LCt50) of TZ is 5 mg·min/.

The medical importance of saxitoxin is in relation to red tide in shellfish and causes the paralytic shellfish poisoning (PSP) food poisoning. The blocking of the sodium channel produces a flaccid paralysis that leaves its victim calm and conscious through the progression of symptoms. Death is from respiratory failure.

My experience in trying to get information from government officials about public health problems is that they always take the immediate event very seriously but rarely say much about the larger implications -- such as whether two saxitoxin appearances in 24 months indicates some kind of long-term ecological change that we need to be worried about.


Blogger Sam said...

this is strange because here in Texas we've already had a closed oyster harvest for an area near Corpus Christi - it was not Vibrio and I forget it's name. Seems early for this kind of thing to be happening.

12:02 PM  

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