Five-year study could solve red tide riddle

By Muriel L. Hendrix
in "Working Waterfront"
September, 1998
Published by the Island Institute

Erratum: Please note that Dr. Don Anderson of The Woods Hole Oceanographic Institution is the lead "originator and investigator" of the ECOHAB-Gulf of Maine project (not Bruce Keafer as stated in the following article). Dr. Anderson has been instrumental in establishing the ECOHAB program nationwide for the study of toxic algae. Gulf of Maine was one of the regions that was initially selected under a peer reviewed process for this important research.

Imagine a time when scientists can forecast "red tide" blooms prior to their growth. Better yet, imagine the day when they know enough about the harmful organisms which cause paralytic poisoning and often death to humans, birds, larval and adult fish and marine mammals, to be able to control their growth.

A five-year, $4.1 million study is underway which may eventually make both scenarios possible, and thus provide the necessary knowledge to reverse the steadily increasing economic losses this phenomenon causes for the fishing industry and the state in general. Research in 1988 revealed that a single paralytic shellfish poisoning outbreak in 1980 cost Maine an estimated $6 million.

The study is a multi-disciplinary effort led by 17 investigators from a variety of institutions, including Woods Hole Oceanographic Institution, University of Maine, Bigelow Laboratory for Ocean Sciences, University of New Hampshire, Dartmouth College and the Canadian Department of Fisheries and Oceans. It is being funded by the National Science Foundation, and the National Oceanic and Atmospheric Administration through their Coastal Ocean Program and Sea Grant Program. The Island Institute is participating as well, funding a contract with Maureen Keller at the Bigelow Laboratory to investigate why Penobscot Bay is relatively free of red tide.

Known as ECOHAB-GOM (the ecology and oceanography of toxic Alexandrium blooms in the Gulf of Maine) - Alexandrium is the organism that causes paralytic shellfish poisoning - the study's proposal states it aims to explore the general questions of "the source of the Alexandrium cells that appear in fresh water plumes in the western Maine coastal current (WMCC), learn about Alexandrium cell distribution and dynamics in the eastern Maine coastal current (EMCC), and determine linkages among blooms in the WMCC, the EMCC and the Bay of Fundy."

Woods Hole Oceanographic Institute marine biologist Bruce Keafer, a research associate for Dr. Don Anderson, Senior Scientist in the Biology Department at Woods Hole, is the originator and lead investigator. Keafer is in charge of the research cruises in the Casco Bay area. The cruises have been based at SMVTI in South Portland, which has given lab support and housing in return for having students in its Applied Marine Biology and Oceanography program participate in cruise work.

Scientists prefer to use the term "harmful algae bloom" (HAB) when talking about what is commonly called "red tide," Keafer said, because red blooms are not associated with tides and most are not toxic.

"We have known for years which organism causes the HAB in the Gulf of Maine," he said, "but what we didn't know are the dynamics of the growth. We think that Casco Bay is the initiation site for blooms that get transported to other areas of the Gulf of Maine to the south and west."

He explained that marine scientists have discovered that the harmful Alexandrium cells, which are dinoflagellates, or microscopic plants, thrive in the fresh water which flows into the Western Maine Coastal Current from the Kennebec River, most heavily in spring. "The organisms are plants and they like the fresh water source," he said. "Their cysts, which are like a seed, germinate in the sediment and swim to the surface in the brackish water column to photosynthesize. When they have enough light and nutrients, they grow and divide, and over a period of time, enough organisms are accumulated in an area to cause a bloom, which can create toxicity in shellfish.

"One of the big questions is if the blooms start inshore or offshore," he said. To get a sense of this, beginning in April and continuing for two and one-half months, researchers hung mussel bags on buoys offshore, and tested them periodically along with mussels on inshore moorings and at inshore sites. "The mussels on the offshore buoys showed toxins first," he said. "Still," he added, "the Kennebec River water travels way offshore in springtime; there is plenty out there to provide the fresh water plumes that the cysts like to use to get to the surface to photosynthesize."

Anderson, who has been studying HABs in the Gulf of Maine for 25 years, said researchers have found the Alexandrium organism in areas they expected to find it, and have collected the information they need to learn more about Casco Bay as an initiation zone.

"The offshore findings were a surprise for us, though," he said. "We thought the bloom began in the shallow waters inside Casco Bay and then traveled down the coast to New Hampshire and Massachusetts. What we've found is that it originates five to ten miles offshore and then moves inshore where it blooms and causes toxicity in nearshore shellfish. It confirms the theory that Casco Bay is the first toxic initiation zone, but we have to rethink now about what is happening offshore to make this happen."

He says that blooms occur later in the season in areas Downeast and in Canada. That section of the Gulf of Maine is being studied by a different research vessel, which is currently obtaining samples to determine if, as researchers speculate, the Bay of Fundy is the initiation zone for that area and toxic organisms travel from it to waters off Washington and Hancock Counties. Historically, he said, Penobscot Bay has been generally free of Alexandrium, a phenomenon attributed to the separation of the EMCC and WMCC. "The EMCC moves offshore to the east of Penobscot Bay, and the WMCC begins to the west. Their movement is almost as if they are not connected, so it is logical to think that the Alexandrium populations are different," he said.

John Hurst, Director of Toxin Monitoring for the state of Maine's Department of Marine Resources and associate investigator in ECOHAB-GOM, has been studying HABs for 40 years. (Chuck Gregory of SMVTI calls him Maine's "grandfather of red tide.") Hurst said he has suspected the Alexandrium organisms originate offshore. "There's a heck of a lot we don't know about it," he said, noting that "Even though we've learned one hell of a lot about Alexandrium in the last 20 to 30 years, I felt more confident with what I thought I knew 20 years ago then I do with what I know now. I know more, but now I know what we don't know."

Hurst hopes the study will produce enough understanding of Alexandrium's behavior to make it possible to predict when and where toxicity will show up, prior to the time when the state needs to make closures.

He also wishes a by-product of the study would be a simpler, less expensive way to test for toxicity, a chemical test to replace the current method, which costs taxpayers considerable money and uses mice. "There is a machine available that makes the toxin fluoresce, but it costs $50,000," he says. "We need something simpler."

There are so many questions to consider, Keafer noted, among them, Why do the toxic cells show up first offshore? Why do they like the fresh water source? Why aren't they found in the Kennebec River? What role does the wind play in distribution? What role do the complex three-dimensional Gulf of Maine currents play in their distribution?

If these mysteries can be solved and predictive models developed which reduce observable parameters of Alexandrium behavior to a manageable number, perhaps then it will be possible for scientists to predict where Alexandrium cells are going to show up in harmful blooms. (An example of a model the ECOHAB researchers are developing can be found at

A good understanding of the dynamics of Alexandrium behavior is necessary before biologists can understand why the bloom has increased dramatically in the past two decades (although Hurst noted that the past two years showed relatively light concentrations of toxin - he believes the phenomenon is cyclic) and how it can be controlled. "At this point, we are not focusing on any control mechanism," Keafer said. "Dr. Anderson is very interested in the question but the research is in its infancy.

"Eventually we may be able to find a way to control it," Anderson said, but that 's in the long haul. The cells are so widely dispersed. It's not like a garden where you can treat it and not affect everything else around your house. If we can figure out where the cells come from, maybe then we can target the problem in a small area.

"If we are going to control it, the best way would be to do this when it first starts. That's why we need to study the source area and learn as much as possible about that, then perhaps we can find ways to control it before it spreads."

Next year, the research teams won't conduct any cruises. Instead, they will analyze their results and use the data to modify cruise plans for the year 2000. In 2001, a series of "process" studies will target key aspects of bloom formation and transport on a small scale. In 2002, all data will be analyzed, pulled together, and published.

Meanwhile, John Hurst assures shellfish lovers that if they buy from a dealer, they will not get sick. "The industry is regulated to the hilt," he says. "Even I'll eat them. But," he adds, "if a person is going out to harvest on his own, in summer especially, it's downright dangerous."

A vast amount of information about ECOHAB-GOM is available at;. - ed.