In computer models and observations, researchers see potential for significant 'red tide' season

Conditions are ripe for another large bloom in New England waters; weather and current patterns will determine outcome

The end of April usually brings the first signs of harmful algae in New England waters, and this year, researchers participating in the Gulf of Maine Toxicity study—led by Woods Hole Oceanographic Institution (WHOI)--are preparing for a potentially big bloom.

A combination of abundant beds of algal seeds and excess winter precipitation have set the stage for a harmful algal bloom similar to the historic “red tide” of 2005, according to GOMTOX principal investigator Don Anderson. The 2005 bloom shut down shellfish beds from the Bay of Fundy to Martha’s Vineyard for several months and caused an estimated $50 million in losses to the Massachusetts shellfish industry alone.

Weather patterns and ocean conditions over the next few months will determine whether this year’s algal growth approaches the troubles of 2005.

GOMTOX oceanographers Dennis McGillicuddy (WHOI) and Ruoying He (North Carolina State University) are several years along in the development of a computer model to predict the intensity and location of blooms of the toxic algae Alexandrium fundyense in the Gulf of Maine.

Though the scientists are reluctant to make an official “forecast” (because bloom outcomes are dependent on weather events that cannot be predicted months in advance), colleagues in coastal management and fisheries believe that even rough seasonal forecasting can be useful in preparing for contingencies.

"With advance warning of a potentially troublesome year for algae, shellfish farmers and fishermen might shift the timing of their harvest or postpone plans for expansion of aquaculture beds,” said Anderson, a WHOI senior scientist in the Biology Department and director of the Coastal Ocean Institute. “Restaurants might make contingency plans for supplies of seafood during the summer, and state agencies can ensure they have adequate staff for the significant monitoring efforts that might be required to protect public health and the shellfish industry.”

Seeds or “cysts” of A. fundyense naturally germinate and turn into cells that swim up from the seafloor around April 1 of each year. By the end of April, cells usually begin to appear in large numbers in the waters off coastal Maine.

The algae are notorious for producing a toxin that accumulates in clams, mussels, and other shellfish and can cause paralytic shellfish poisoning (PSP) in humans who consume them.

According to a seafloor survey conducted in the fall of 2007 by Anderson’s team, the number of Alexandrium cysts—the dormant, seed-like stage of the algae’s life-cycle—is more than 30 percent higher than what was observed in the sediments prior to the historic bloom of 2005. The seed beds were especially rich in mid-coast Maine, origin of many of the cells that affect western Maine, New Hampshire, and Massachusetts.