From the Gulf of Mexico to the Gulf of Maine, from the Pacific Northwest to the Atlantic, harmful algal blooms (HABs), are increasingly darkening coastal waters and alarming both scientists and citizens. "We have more toxic algae, more toxins produced by algae, more areas affected in the United States and the world, and more resources affected," states Donald M. Anderson, Woods Hole Oceanographic Institution (WHOI) senior scientist. The number of reported bloom events is significantly higher than those noted just two decades ago. According to Anderson, the only coastal state in the continental United States that has not been affected by HABs is "Georgia, period."

Anderson presented an overview of the global impact of HABs during a February 1998, single-issue media briefing sponsored by the National Sea Grant Office. He joined a panel of HAB experts that included Darcy Lonsdale, associate professor of ecology at the State University of New York (SUNY) at Stony Brook; Rose Ann Cattolico, University of Washington botany professor; and JoAnn Burkholder, North Carolina State University botany professor and codiscoverer of Pfiesteria. Each gave the press a succinct report of Sea Grant-supported as well as other research on Aureococcus (brown tide), Heterosigma and Pfiesteria, respectively. This press briefing generated newspaper stories and in-depth radio broadcasts about harmful algal blooms that reached millions of readers and listeners nationwide.

Why Harmful?

Each harmful algal species impacts the ecosystem and the human population differently. The HAB with the most dramatic effects is Pfiesteria, which, according to Burkholder and others, has caused the deaths of billions of fish in North Carolina and Maryland, as well as memory loss in fishermen and researchers who have been in close contact with the organism. In the Northeast, Alexandrium poses the greatest danger: People who eat shellfish that contain the neurotoxin produced by these algae can become paralyzed and even die.

The economic impacts of HABs are significant. In Long Island’s shallow bays Aureococcus has devastated the economically important scallop population. Closed shellfish beds there and elsewhere have resulted in losses of businesses and jobs. The cost of cleaning up fish kills has risen, as have the medical costs of workers exposed to airborne algal toxins. Tourism that normally flourishes in coastal areas of Florida is flushed out by red tide, which is sometimes accompanied by noxious odors. The demand for water monitoring and seafood product testing has escalated. In a recent Congressional hearing to discuss increases in research funding, Sen. Olympia Snowe of Maine estimated that harmful algal blooms now carry an annual price tag of $35 million to $65 million for the fishing industry alone.

Harmful algal species are generally microscopic phytoplankton, tiny pigmented organisms that make their own food by photosynthesis. The brown tide organism, Aureococcus, is an extremely small "golden-brown" alga. Alexandrium, Gymnodinium, and Pfiesteria are dinoflagellates, organisms that, although photosynthetic, can also be predators under certain conditions. In the case of Pfiesteria, a single organism can "morph" into 24 different forms, depending on where it is in its life cycle and what is available to eat.

An algal bloom is not necessarily an indicator that a species is harmful. Most algal blooms occur in natural yearly cycles and provide food, especially for shellfish and juvenile finfish. Historically, HABs were commonly called "red tides" because the density of the organisms gave the water a reddish hue. (However, not all HABs are associated with a change in water color.) During red tide conditions, winds can carry and distribute toxins through the air, causing human illness even to those not in direct contact with the water. In the case of brown tide, the tiny algae are packed with a density that can reach over a million cells per milliliter. A bloom of just half that density has a toxic effect on organisms feeding on it.

To HAB and HAB Not

HABs have probably always existed, but their persistence in recent years may result from human activity. Some speculate that algae are being transported in ships’ ballast tanks or that offshore blooms are being carried by currents. Nutrients released from fertilizer, sewage, and other runoff may also cause HABs. "Human actions alone have doubled the amount of active nitrogen moving around on
the landscape," Scott Nixon, Rhode Island Sea Grant director, observes. Runoff from developed coastal areas "enriches" the water, making nutrients such as nitrates available to algae and stimulating their growth.

The alarming increase of HABs in the United States prompted establishment of the Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) in 1995. Funded by NOAA’s Coastal Ocean Program (COP), the National Science Foundation’s (NSF) Division of Ocean Sciences, the Environmental Protection Agency (EPA), the Office of Naval Research (ONR), NASA, and the Department of Agriculture, ECOHAB works to determine the causes of HABs and develop ways to predict and control them.

According to Susan Banahan, a Coastal Ocean Program project manager, funding agencies are "looking at all the problems, all the approaches." Research proposals are reviewed by scientists and other experts to focus on "what projects will produce the kinds of information that they (agencies and scientists) need to do their jobs of protecting health and protecting the environment." What has emerged from this call for research is cooperation among agencies, including Sea Grant, as well as the communication of research results among scientists and to the public.

Collaboration on Brown Tide

As part of the three-year Brown Tide Research Initiative (BTRI), NOAA’s COP has funded eight projects that are being administered by New York Sea Grant. BTRI investigators are working on brown tide in Maine, Massachusetts, Rhode Island, Connecticut, and New York, as well as Delaware, Maryland, and Virginia. A recent brown tide informational symposium held by New York Sea Grant provided scientists an opportunity to share insights not only with one another, but also with a far wider audience.

"Teamwork among the scientists, monitoring groups, and agencies will make a critical difference in the speed and effectiveness of our efforts to find answers. New York Sea Grant’s coordinated BTRI Program is an excellent example of how useful this collaboration can be," explains Cornelia Schlenk, New York Sea Grant assistant director and BTRI steering committee chair.

Brown tide is a particular problem in the bays of Long Island, where several BTRI researchers are examining ecological triggers that may initiate blooms. Along the beach of beautiful Coecles Harbor in Shelter Island, SUNY’s Lonsdale and David Caron, WHOI senior scientist, used 300-gallon plastic tanks containing water from the harbor to simulate conditions of shallow bays. Among several experimental treatments, one–the addition of sediment and sediment-containing seed clams to these tanks, or mesocosms–triggered a population explosion of brown tide algae.

Lonsdale has examined the feeding relationships between microscopic animal grazers and their phytoplankton prey. Finding that, when brown tide algae make up 75 percent of the food supply, protozoans stop feeding, Lonsdale hypothesizes that protozoan grazers are selective and suggests that an increased number of selective grazers may allow a greater number of brown tide algae to flourish, thus initiating a bloom from the "top down." He also hypothesizes that the nutrient load, especially nitrogen, may stimulate a brown tide, thus initiating a bloom from the "bottom up."

Sea Grant Scholar Christopher Gobler, who has conducted research with Sergio SanudoWilhelmy, SUNY Stony Brook assistant professor, explained that a 1995 bloom in West Neck Bay, Shelter Island, was preceded by very high organic nitrogen levels. But a 1997 bloom was preceded by a high iron content. The researchers conclude that, while organic nutrients may not be required to initiate a bloom, they may be important to sustain it. However, according to Gregory Boyer, associate professor at the SUNY College of Environmental Science and Forestry in Syracuse, the tiny alga–only one ten-thousandth of an inch–is "very ordinary" in how it goes about using nutrients, such as iron.

One important question is how brown tides affect shellfish. At about a quarter of a million algal cells per milliliter of water, the cilia that usually help these animals ingest food just stop: The bivalves no longer feed. V. Monica Bricelj of the Canadian National Research Council has investigated mussels, clams, scallops, and oysters and has found that toxicity varies among laboratory cultures of brown tide. Even when there is a mix of nutritious algae and brown tide in the water, bivalve feeding is still adversely affected.

In 1985, a severe brown tide virtually eradicated Long Island Bay’s $2 million annual bay scallop industry. Stephen T. Tettlebach, biology and marine science associate professor at Long Island University’s Southampton College, may help gauge the impacts of various levels of brown tide on these shellfish. Tettlebach’s research findings presented at the Sea Grant symposium indicate that, while bay scallops can reproduce under brown tide conditions, their subsequent growth and recruitment are hindered.

So why does the brown tide alga bloom to the tune of a million cells in a tiny milliliter of bay water? Theodore Smayda, University of Rhode Island Graduate School of Oceanography (URI GSO) research professor of oceanography, said there seem to be three different general causes of blooms. Some HABs are stimulated by nutrients mixed into the sediment and water, others are stimulated by chemicals, and still others are brought about by a combination of physical factors, such as flushing of the bay and wind conditions. These factors may differ in importance according to location. In Long Island’s Peconic Bays, nutrients are probably the most important factor, whereas in Rhode Island’s Narragansett Bay, the bay’s inability to flush seems to be a predominant factor.

The timing of the bloom is also important, says BTRI researcher Terry Cucci of Bigelow Laboratory for Ocean Sciences in Maine. As spring progresses into summer, then fall, the dynamic world of the bay changes, shifting the balance of biological, chemical, and physical factors that potentially could cause a brown tide.

"To date, not all the pieces are there yet, but it’s nice to see parallel tracks among these projects," says BTRI researcher Patricia Glibert of Horn Point Environmental Laboratories in Maryland. "The strength of the BTRI is the multifaceted approach," she added. "But trying to predict harmful algal blooms is like trying to predict a tornado."

From Plume to Bloom

Predicting blooms and monitoring likely sites are important aspects of Northeast research projects focused on several species of Alexandrium. The effects of these algae are magnified in environments in which they are the main course for filter-feeding shelled invertebrates, such as clams, mussels, oysters, and scallops. Large concentrations of algal toxins may accumulate in the invertebrate tissue. If the shellfish are consumed by humans, the effects can be deadly: In paralytic shellfish poisoning (PSP), a neurotoxin shuts down the body’s nervous system, causing paralysis or even death. Fortunately, at least so far, such effects are rare.

Along the southern New England coast a massive Alexandrium tamarense bloom first closed shellfish beds in 1972, and many beds there have remained closed since. In 1989, shellfish beds on Georges Bank and Nantucket Shoals became affected, showing further expansion southward. Seeking the cause of this widespread distribution of A. tamarense, Peter J.S. Franks of the Scripps Institute of Oceanography and WHOI’s Anderson found that during the late spring and early summer, the freshwater flow from southern Maine’s rivers into the Gulf of Maine formed a buoyant plume. The plume’s upwelling and downwelling, along with currents and winds, worked to spread the toxic algae.

A current Maine/New Hampshire Sea Grant project is exploring whether the Kennebec River and its plume are the source of Alexandrium now threatening fisheries in the western Gulf of Maine and whether the plume is aiding the flow of HABs from Casco Bay into Massachusetts Bay and Georges Bank. Neal Pettigrew, University of Maine School of Marine Sciences associate professor of oceanography, and Maureen Keller, Bigelow Laboratory for Ocean Sciences scientist, are correlating hydrographic and current data with satellite images to find the mechanisms that generate the algal bloom in Casco Bay and sustain the "seed" population after the bloom is moved southward by the coastal current.

Last October, the R/V Gulf Challenger cruised the Gulf of Maine under Bruce Keafer, WHOI chief scientist, to map the Alexandrium cysts. Alexandrium can lie dormant for years as protected cysts on the seafloor. These cysts germinate in spring, inoculating the water with a seed population. By mapping the cysts, researchers can determine the germination potential. These mapping efforts suggest to Keafer that Alexandrium blooms may not be initiated within Casco Bay but come from more abundant cyst beds several miles offshore. However, the cysts closer to shore are likely to be exposed to warmer temperatures. If the timing is right,
those cysts could lead to a bloom as well.

Given the serious risks of HABs, monitoring their whereabouts and keeping people informed are critical. ECOHAB field studies on Alexandrium within Massachusetts Bay and northward helped provide information crucial to the policy debate about the impact of Boston’s sewage outfall relocation. ECOHAB’s extensive Internet Web site provides viewers a map of Alexandrium cysts in Casco Bay, Maine, as well as monitoring data from 363 toxicity stations throughout the Gulf of Maine.

In many parts of the country, scientists and regulatory agencies work together in their monitoring efforts. In Florida, regulators sound the alarm by closing shellfish beds when a red tide comes in–even though the practice is unpopular with fishermen and businesses. On Long Island, the county health department monitors brown tide cell counts regularly, and researchers use that information to investigate new theories to help predict blooms. Public outreach also plays a part in raising awareness about potential dangers, as evidenced by the New York Sea Grant brown tide symposium that brought scientists together with a broad spectrum of concerned individuals–educators, baymen, members of the seafood industry, and the public.

As with any problem, prevention is unquestionably preferable to treatment. While scientists don’t have a way of stopping HABs before they start, they are working on new techniques to limit impacts. With funding from New York Sea Grant, SUNY’s Boyer is developing an onboard toxin analyzer to identify contaminants in shellfish. This device will allow commercial fishing crews to take samples from a potential shellfish bed and get test results within minutes, not days, as is currently required. By employing this new technology properly, fishing crews won’t harvest shellfish contaminated by harmful algae, much less take it to market.