Environmental Factor, August 2007, National Institute of Environmental Health Sciences

Oceanographer Reports on Red Tide in the Gulf of Maine

By Eddy Ball
October 2007

According to Anderson, Alexandrium is self-seeding, replenishing the cyst population and expanding nesting beds every summer. (Photo courtesy of Steve McCaw)

Host Fred Tyson is a program administrator in the Susceptibility and Population Health Branch of the Division of Extramural Research and Training (DERT), which administers grants to the Oceans and Human Health Centers. (Photo courtesy of Steve McCaw)

Anderson maintained his audience’s interest with his account of unraveling the mysteries surrounding HABs. His talk kept some people, such as Tyson’s colleague DERT Program Analyst Liam O’Fallon, literally on the edge of their seats. (Photo courtesy of Steve McCaw)

Woods Hole Oceanographic Institute (WHOI) Senior Scientist Donald Anderson, Ph.D., was the featured speaker in the NIEHS Frontiers in Environmental Sciences Lecture Series on August 31 in Rodbell Auditorium. Hosted by Fred Tyson, Ph.D., Anderson’s lecture was titled “Don’t Eat the Clams: Managing the Threat from the New England Red Tide.”

Along with his work as a marine biologist at Woods Hole, Anderson is the director of the WHOI Coastal Ocean Institution and the U.S. National Office for Marine Biotoxins and Harmful Algal Blooms (HABs). He is also one of the lead investigators at the Woods Hole Center for Oceans and Human Health, which is jointly funded by the NIEHS Centers for Oceans and Human Health and the National Science Foundation (NSF).

For much of his career, Anderson has focused on the natural phenomenon of cyclical HAB outbreaks along the New England coast. A 2005 outbreak in that region of the species of Alexandrium that secretes Paralytic Shellfish Poisoning (PSP) inducing toxins endangered the lives of several careless fishermen and resulted in a $50 million loss to the Massachusetts fishing industry.

Anderson’s efforts are directed at understanding the life cycles of these HABs and developing hydrodynamic conceptual models to help predict the outbreaks of what is popularly known as the New England “red tide.” “The term ‘red tide’ is misleading,” he explained, because in fact many harmless organisms can produce the characteristic red tint, while water containing several of the most harmful species retains its natural color.

“It’s a problem where shellfish have filtered several types of algae from the water as food and accumulated that toxin to dangerous levels,” Anderson said. “The most widespread of all of the HABs, it [PSP] is virtually everywhere” in the world’s coastal environments. At high enough concentrations, he noted, “If anyone in this room ate two or three clams [containing the very stable poison saxotoxin that is produced by Alexandrium], it would be lethal.”

Investigations into the life cycle of Alexandrium from cyst to bloom have taken Anderson into the nesting beds off the coast of Nova Scotia in the Bay of Fundy, along the coasts of Maine, New Hampshire and Massachusetts where coastal currents and storms spread the organisms as far south as Martha’s Vineyard, and, most recently, into the international waters of Georges Bank.

Georges Bank is a comparatively shallow fishing area along the coastal shelf 120 kilometers off the coast of Massachusetts. Although its rich sources of cod and other species have declined, Georges Bank is still a $100 million annual shellfish resource where high concentrations of the organism now are flourishing. These fishing grounds, Anderson explained, may turn out to pose a significant human health threat if HAB populations increase as predicted — and create a regulatory nightmare for states on the New England and even Mid-Atlantic coasts.

Until recently, record keeping of the outbreaks was spotty. Thanks to work by Anderson’s group and other researchers, analysis of data from the past three decades has become much more sophisticated with improved models. New technology, including the Environmental Sampling Processor robot armed with DNA and small-unit RNA probe arrays, promises to increase real-time data gathering on specific HAB populations for more accurate forecasting.

Unfortunately, even as prevalence worldwide increases, Anderson observed, “There are still more questions here than answers.” There is considerable victim variability, and scientists have been unable to predict how much non-indigenous seeding is taking place in such places as Georges Bank. Also, the organism is “made for survival” with a cyst viability rate of 50 percent after five years — and some cysts may remain viable for up to 30 years.

“I want to emphasize that this partnership between NIEHS and NSF is so timely and so important,” Anderson concluded, “because it’s bridging this gap between this human health problem and the oceanography involved.”

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