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Red Tide Likely To Hit New England In 2010

by the Fish Site Editor
01 March 2010, at 12:00am

US - The New England shellfish industry faces the threat of widespread red tide outbreaks this spring and summer that could force hundreds of miles of clam flats to be closed and lead to clam shortages.

An outlook for a significant regional bloom of a toxic alga that causes 'red tides' has been issued by the NOAA-funded Gulf of Maine Toxicity project.

The outlook is based on a seafloor survey of the seed-like cysts of Alexandrium fundyense, an organism that causes harmful algal blooms, sometimes referred to as ‘red tides’. Cysts deposited in the fall hatch the following spring; last fall the abundance of cysts in the sediment was 60 percent higher than observed prior to the historic bloom of 2005, indicating that a large bloom is likely in the spring of 2010.

The cyst bed also appears to have expanded to the south, so the 2010 bloom may affect areas such as Massachusetts Bay and Georges Bank sooner than has been the case in past years.

Although the algae in the water pose no direct threat to human beings, toxins produced by Alexandrium can accumulate in filter-feeding organisms such as mussels and clams, which can cause paralytic shellfish poisoning in humans who consume them. In order to protect public health, shellfish beds are monitored by state agencies and closed when toxin concentrations rise above a quarantine level. There have been no illnesses from legally harvested shellfish in recent years despite some severe blooms.

Scientists are reluctant to make a “forecast” of precisely where and when the bloom will make landfall because bloom transport depends on weather events that cannot be predicted months in advance.

“Our research has shown that cyst abundance in the fall is an indicator of the magnitude of the bloom in the following year,” said Dennis McGillicuddy, a senior scientist with Woods Hole Oceanographic Institution and member of the Gulf of Maine Toxicity project, or GOMTOX. “Even if there is a large bloom offshore, certain wind patterns and ocean currents in the late spring and summer are needed to transport it onshore where it can affect coastal shellfish.”

This year’s bloom could be similar to the major blooms of 2005 and 2008, according to Don Anderson, a biologist with Woods Hole Oceanographic Institution and principal investigator of the GOMTOX study. The 2005 bloom shut down shellfish beds from Maine to Martha’s Vineyard for several months and caused an estimated $20 million in losses to the Massachusetts shellfish industry alone.

Government agencies and researchers believe that the regional-scale, seasonal outlook can be useful in preparing for contingencies. “NOAA’s goal is to provide tools to prevent, control, or mitigate the occurrence of harmful algal blooms and their impacts,” said David M. Kennedy, acting assistant administrator for NOAA’s National Ocean Service. “This advanced warning, along with updates during the season, can help state agencies prepare for monitoring harmful algal blooms and assessing public health risks.”

Early warnings can give shellfish farmers and fishermen the opportunity to shift the timing of their harvest or postpone plans for expansion of aquaculture beds. Area restaurants may also benefit from advance warnings by making contingency plans for supplies of seafood during the summer.

GOMTOX researchers regularly share their field observations and models with more than 80 coastal resource and fisheries managers in six states as well as federal entities like NOAA, the Environmental Protection Agency and the Food and Drug Administration.

“’Red tide’ is a chronic problem in the Gulf of Maine and states have limited resources to handle it,” said Darcie Couture, director of Biotoxin Monitoring for the Maine Department of Marine Resources. “When we get this information about the potential severity of a bloom season and the dynamics of the bloom once the season has started, then it gives us an advantage in staging our resources during an otherwise overwhelming environmental and economic crisis.”

Ruoying He, associate professor at North Carolina State University and GOMTOX member, will present data and models on the projected bloom at the 2010 Ocean Sciences Meeting today in Portland, Ore.

the Fish Site Editor