Harmful Algal Blooms (Diving Deeper podcast, 10.7.09)
Microscopic image of Alexandrium fundyense cysts, the "seeds" that fall to the ocean bottom at the end of one season's blooms. Under the right conditions, these cells can germinate the following year to initiate another season's blooms. Courtesy: Woods Hole Oceanographic Institution
On February 24, researchers with the NOAA-funded Gulf of Maine Toxicity (GOMTOX) project issued an outlook predicting a significant bloom of Alexandrium fundyense, the red tide algal species, in the Gulf of Maine in the spring and summer of 2010. In response to this outlook, the state of Maine began monitoring shellfish toxicity three weeks earlier than normal.
Shellfish toxicity quickly exceeded the regulatory limit, so the state declared a shellfish harvesting closure on March 24 for certain areas in Casco Bay. Future closures will be heavily dependent on whether weather conditions foster Alexandrium growth and transport to near shore shellfish beds.
Although the algae pose no direct threat to human beings, toxins produced by this species 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 the public, state authorities shut down shellfish beds affected by blooms.
The advanced warning allows harvesters the opportunity to collect shellfish before beds are closed.
Closures during the historic bloom in 2005 were estimated to have resulted in approximately $18 million in lost shellfish sales in Massachusetts and $4.9 million in Maine, but these estimates do not account for indirect effects on businesses linked to the shellfish industry. Due to effective monitoring by state agencies, there have been no illnesses from legally harvested shellfish in recent years despite some severe blooms during those periods.
Warning state managers about this significant bloom has provided them time to act in a timely manner to protect the health of shellfish consumers from the serious threat this toxic bloom poses. Area restaurants may also benefit from advance warnings by making contingency plans for supplies of seafood during the summer.
The GOMTOX project, funded by NOAA’s ECOHAB Program, is a collaboration of investigators from NOAA, Woods Hole Oceanographic Institution, North Carolina State University, University of Maine, University of Massachusetts Dartmouth, Rutgers University, the Food and Drug Administration, the Canadian Department of Fisheries and Oceans, Maine Department of Marine Resources, Massachusetts Division of Marine Fisheries, and the New Hampshire Department of Environmental Services. Other support for Alexandrium studies in the Gulf of Maine is provided by the National Institutes of Health and the National Science Foundation (through the Woods Hole Center for Oceans and Human Health).