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Red Tide May Break Records

By Ed Kang
May 2010

Donald Anderson, Senior Scientist and Director of the WHOI Coastal Ocean Institute and Rinehart Coastal Research Center.
In September 2007, Senior Scientist and Director of the WHOI Coastal Ocean Institute and Rinehart Coastal Research Center, Donald Anderson, gave a presentation (see story( at NIEHS. (Photo by Pat Tester, NOAA)

specially equipped vessel shown
Shown above is one of the specially equipped vessels WHOI employs to gather samples of water off the New England coast. Accurate prediction and frequent monitoring are essential for developing advance warning of human health impact. (Photo courtesy of WHOI)

NIEHS-funded( scientists from the Woods Hole Oceanographic Institution (WHOI) are monitoring a potentially significant regional bloom of toxic algae, popularly known as the New England "red tide." This spring and summer, these Harmful Algal Blooms (HABs) of toxic Alexandrium could threaten the New England shellfish industry - and less-than-careful consumers - by contaminating filter feeders such as clams and mussels.

Biologist Donald Anderson, Ph.D.( Exit NIEHS, principal investigator of the Gulf of Maine Toxicity (GOMTOX) project jointly funded by NIEHS and the National Science Foundation (NSF), has been studying HABs and their cyclical outbreaks along the New England coast for much of his career. He and a team of co-investigators have developed a sophisticated computer model( Exit NIEHS to help predict the intensity and location of blooms of Alexandrium in the Gulf of Maine.

2010 could see massive bloom

This year, abundant cyst populations have set the stage for a potentially record-breaking bloom. A cyst survey conducted in late 2009 shows the highest number of cysts the GOMTOX team has ever measured - more than 60 percent higher than what was observed immediately prior to the historic red tide of 2005.  The cyst bed also appears to have expanded to the south.

The 2005 bloom shut down shellfish beds from Maine to Martha's Vineyard for several months, causing $50 million in losses to the Massachusetts shellfish industry. A 2008 outbreak was similar in scale.

"This year's bloom could be even larger," explained Anderson. "But the prediction is weather dependent. Strong northeast winds in May, June, or July, would drive Alexandrium towards the coast and sensitive shellfish beds."

Seafood industry and consumers at risk

While significant blooms have a tremendous environmental and economic impact, regional scale studies and monitoring are useful in preparing for contingencies and preventing exposure to humans.

Although the algae in the water pose no direct threat to human beings, "eating just a few affected clams could be lethal," cautions Anderson. "There have been severe cases of paralytic shellfish poisoning (PSP) in individuals who ignored these warnings."

Advanced warning and frequent updates can help state agencies prepare for public health risks and give precious time to help shellfish farmers, suppliers, and restaurants make alternate plans. State agencies close shellfish beds when toxicities rise above dangerous levels. In fact, despite severe blooms in recent years, state agencies have prevented any illness from legally harvested shellfish.

Thus far in 2010, an early season closure of a shellfish bed in the Casco Bay area of Maine indicates that Anderson and his colleagues' models and simulations might be on target.

"Unfortunately, worldwide prevalence of 'red tide' is increasing," Anderson observed. "Our research is focused on bridging the gap between oceanography and this growing human health problem."

Maps of the Gulf of Maine
Maps of the Gulf of Maine reveal the concentration of Alexandrium cysts buried in seafloor sediments. The cyst abundance in 2009 is the highest ever observed in past surveys. Note also that the Alexandrium cyst "seedbed," shown in red, extends farther to the south than was ever observed before. (Courtesy of Don Anderson and the Woods Hole Oceanographic Institution)

(Ed Kang is a public affairs specialist in the Office of Communications and Public Liaison and a regular contributor to the Environmental Factor.)

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