Red tide rears its head — already


James Wright, Senior Editor

Published on
March 23, 2010

In late February, scientists at the Woods Hole Oceanographic Institute (WHOI) in Woods Hole, Mass., predicted another “significant” outbreak of red tide in the Gulf of Maine this summer that would pose a serious threat to New England’s shellfish harvest.

On Tuesday night, the Maine Department of Marine Resources (DMR) reported that shellfish samples taken from certain areas along the Maine coast had detectable levels of the biotoxin — a full month earlier than in recent years.

“The forecast predicting the potential for a bad year was based largely on the presence of an extremely large cyst bed just offshore,” said Darcie Couture, director of biotoxin monitoring at DMR. “Even if all of the cysts bloomed into red tide, there was still a small chance that it could remain mostly offshore, where it would not be a huge problem in our coastal shellfish, unless we got some consistent northeast winds, which would then deliver the cells right into our bays, and become a huge problem. Well, if you’ve been paying attention at all to the weather patterns lately, you would have noticed that we have had a string of consistent northeast winds in our area.”

Red tide is caused by naturally occurring algal blooms (Alexandrium fundyense) that produce a toxin ingested by feeding shellfish. While harmless to bivalves like clams, mussels and oysters, high levels of red tide toxins can cause people who eat them to become sick or even die. Illnesses in humans are commonly referred to as paralytic shellfish poisoning, or PSP.

Red tide outbreaks have forced the closure of some New England shellfish beds to harvesting in recent years, causing a lapse in the region’s clam, mussel and oyster supplies. Outbreaks in 2005 and 2008 were particularly harmful, resulting in extended closures from the Maine-Canada border to Martha’s Vineyard off the coast of Massachusetts.

According to Couture, the first tests this spring, conducted some three weeks earlier than normal, showed that mussels from Lumbos Hole scored a 56, enough to warrant a closure. Couture expected to issue a closure for mussels and carnivorous snails in the Harpswell Sound and Quahog Bay area as early as Wednesday, but added that the New Meadows River and Casco Bay could be closed to mussel harvesting very soon.

“Everyone should take this early start to the season very seriously and make the most of your harvest areas while they remain open,” said Couture.

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