When sunlight streams through the eelgrass beds of Peconic Bay, the mid-Atlantic estuary turns an emerald color reminiscent of tropical waters. The baymen's homes that dot the shores of Long Island attest to a centuries-old tradition of shellfish harvesting along the Eastern Seaboard. Until a decade ago, baymen yielded a delicacy from the Peconic - a buttery scallop - found few other places in the country.
After brown tide, things changed.
By: Julie Zeidner
New York Sea Grant
The microscopic alga Aureococcus anophagefferens, named brown tide for the muddy color it turns the water, first appeared in Peconic Bay in 1985. Complaints by citizens concerned about the pristine Bay, which suddenly looked dirty, were filed at the Suffolk County Department of Health Services (SCDHS) on Long Island. When scallops and mussels started to die, baymen also reported something awry.
"There was a major darkening," said Roger Tollefsen, New York Seafood Council president, remembering the first time brown tide appeared. "Then the water settled into clear brown. When that happened, the alarms went off. There was bewilderment because no one knew what was happening."
Not only did a massive algal bloom strike Peconic Bay, but that same summer of '85 a bloom reached levels of a little over one billion cells per liter in Rhode Island's Narragansett Bay. Since Narragansett Bay's first bout with brown tide, the organism has mostly disappeared from there. However, it has continued to plague Long Island embayments, as well as New Jersey's Barnegat Bay.
For scientists, brown tide represents one of a growing number of harmful algal blooms increasing in incidence and variety around the world. A. anophagefferens was first characterized and named in 1985 by University of Rhode Island (URI) researchers, including John Sieburth, professor emeritus; Paul Johnson, microbiology research associate; and Paul Hargraves, oceanography professor.
Since the discovery of brown tide, scientists have accumulated substantial information about the life cycle of the organism and its effects on other marine plants and animals. An antibody probe to detect brown tide, developed by Woods Hole Oceanographic Institution biologist Donald Anderson, has enabled scientists to easily distinguish this organism from other microscopic algae. Researchers, including phytoplankton ecologist Elizabeth Cosper at the State University of New York's Marine Sciences Research Center (MSRC), have been able to single out factors, like iron, that stimulate the growth of brown tide and to isolate naturally present viruses in seawater that can rapidly lead to its demise. Throughout this period, the National Sea Grant College Program has committed funds for brown tide research in every state where the problem has occurred. The SCDHS has also devoted research funds for this problem. But scientists concede that they are still far from finding a cure for brown tide, since the organism is still not fully understood. And the public is frustrated because the cause of and solution for brown tide remain a mystery.
The dramatic blooms in the Northeast captured the attention of Cosper, who had also isolated the brown tide organism in laboratory experiments in 1986. "It's very small, even magnified 30,000 times," she said. "It's just a little pimple."
But collectively, brown tide blooms can form such a thick layer in the water that they block sunlight to eelgrass and other underwater plants. Without light, the habitat that scallops and other marine life depend on for shelter is destroyed. Brown tide not only blocks sunlight, but also has a severe toxic effect on bivalves, inhibiting their ability to eat, grow, and reproduce.
These effects on shellfish have been demonstrated by V. Monica Bricelj, MSRC benthic ecology professor, and Gregg Tracey, a Science Applications International Corporation oceanographer. The mucous-like coating of brown tide might clog the gills of shellfish that derive nutrients by filtering algae out of the water, said Tracey, who conducted laboratory and field studies of blue mussels affected by the brown tide in Narragansett Bay. "When the mussels were unable to feed, they reversed their reproductive cycle and started to resorb their eggs to survive," Tracey said.
The sudden emergence of brown tide might have been caused when an ocean organism, which resembles a tiny plankton found in Australian and Norwegian waters, was swept by currents into shallow embayments along the Atlantic Seaboard and Gulf Coast, where it prospered under favorable environmental conditions, Cosper said. There were droughts in both Rhode Island and New York the summer brown tide first appeared. A common theory is that brown tide was able to grow better in the warm, shallow estuaries because the water was sluggish and salinity had increased to levels that favored the alga.
In addition to wiping out scallop and mussel populations, and diminishing the size and quality of hard clams, brown tide can do harm to other marine life. Its negative impact on microscopic organisms that form the basis of the food chain for larger fish is shown by the work of Darcy Lonsdale, MSRC zooplankton ecology professor, and Gordon Taylor, MSRC microbiology professor. Their field studies showed a decrease in feeding and growth rates of ciliates, a group of unicellular organisms that are major grazers of phytoplankton. Since ciliates are an important food source for other organisms, including zooplankton and fish larvae, this finding shows how brown tide's toxic effect ripples through the food chain.
The Peconic Bay scallop, one of Long Island's most valued products, had a dockside value of $2 million and represented 27 percent of the entire bay scallop sales in the United States prior to brown tide, Tollefsen said. The algal blooms have reduced the annual fall scallop harvest yields to only a few thousand dollars.
After brown tide struck again in 1995, political pressure mounted to thwart further economic hardship for scallop harvesters on Long Island. Other fishery resources and the tourism industry were also at stake. Scientists from across the United States, government officials, and local residents met for a Brown Tide Summit in Islip, N.Y., to review information about brown tide and to develop a plan encompassing local, regional, and national efforts to address the problem. The summit was sponsored by New York Sea Grant, MSRC, and the Peconic Estuary Program, with funding provided by the National Oceanic and Atmospheric Administration (NOAA).
"Brown tide reared its ugly head this year, after we all basked in the glory of a wonderful scallop crop the previous year," U.S. Rep. Michael Forbes of New York said at the summit. "If we lose a grip on shellfishing and the fishing industry in general, we lose the heart and soul of this area that we love."
During the two-day summit, scientists reported on studies of factors in the environment that might cause brown tide to grow. Their results to date have not clarified the impacts human and industrial waste products have on the brown tide organism. Inorganic nutrients, like nitrogen and phosphorus (contained in sewage effluent and urban runoff), which stimulate the production of algae in some estuaries, appear to have little or no direct effect on the growth of brown tide.
URI researchers conducted mesocosm studies in shallow tanks designed to simulate conditions in Long Island's Great South Bay or Rhode Island's salt pond lagoons, where brown tide has occurred. Nitrogen and phosphorus were reduced by 50 percent in control tanks to reflect unpolluted coastal seawater that enters coastal lagoons. "That summer brown tide didn't bloom in Rhode Island's ponds or bays, but it did bloom in our tanks," said Scott Nixon, Rhode Island Sea Grant director and principal investigator of the brown tide mesocosm study. "We don't have the faintest idea why brown tide bloomed. The only difference was that the control tanks had a low input of nitrogen and phosphorus."
While brown tide may not be stimulated by these nutrients, a recent New York Sea Grant-sponsored study by Cosper and Sea Grant scholar Chris Gobler showed that increased domestic water usage is pumping more micronutrients, such as iron and selenium, into the bays, which might contribute to blooms. Iron bound to compounds like citric acids, used in new laundry detergents, might also stimulate brown tide.
An explosion of harmful algae - from brown tide to toxic dinoflagellates like red tide and Gymnodinium breve - impacting marine ecosystems and fisheries resources worldwide, points to changes in the environment that scientists are just beginning to understand. Tides that kill fish and foul water have been recorded since biblical times, when Moses cursed the Egyptians. Scientists theorize that the event described in Exodus 7:17, in which all the waters of Egypt turned to blood, was actually a harmful algal bloom much like the red tides we see today. But have algal blooms like red tide always existed or are they just being measured more frequently now? The general scientific consensus is that algal blooms are increasing in incidence, Tracey said. "Formerly only a few regions [in the United States] were affected by harmful algal blooms in scattered locations," Anderson says in a recently issued report, ECOHAB: (Ecology of Harmful Algal Blooms) a National Research Agenda. "But now virtually every coastal state is threatened, in many cases over large geographic areas and by more than one harmful or toxic species."
Scientists are trying to determine what changes in the environment might be promoting algal blooms like brown tide. Explanations for the expansion of these harmful blooms include coastal development, global warming, and transport of algae in ballast water. Anderson said that one of the impediments to a better picture of how brown tide operates is limited funding for the problem. Funding tends to fluctuate with the sporadic appearance of brown tide. Also, since brown tide blooms are not always present, it is difficult to conduct research for a long enough period of time to get definitive results. Until the basic biology of brown tide is understood, there is little hope of managing the problem.
But bay people say finding a solution to save the scallop fishery demands immediate attention. "Scallop aquaculture programs may provide a short-term answer", said Chris Smith, Cornell Cooperative Extension specialist. Smith serves as a technical advisor to the Long Island Green Seal Program, a bay scallop seeding effort run by a committee of baymen. "By planting a small number of scallops through seeding programs, you can create a significant economic harvest," said Smith, noting that 25 percent of the 1989 scallop crop was from scallops planted by Green Seal's seeding program in 1988.
Scallop restoration in Rhode Island has not been as successful, said Michael Rice, Sea Grant researcher and URI fisheries and aquaculture associate professor. "We really haven't had a rebound in our scallop populations in the last decade," he said. "After the brown tide event, we had this shift from a sea grassÐdominated ecosystem to a brown muddy bottom. This is not so good in terms of scallop habitat." Scallop aquaculture in Japan, where fine-mesh bags are used to mimic eelgrass, has yielded much better results than scallop harvesting techniques employed in the United States, Rice noted, but the technology hasn't been used very often here. (See related story, Raising Scallops with the Greatest of Es)
The economic loss of the scallop fishery could also have adverse effects on other commercial fisheries, according to economists James Kahn and Mark Rockel in a 1988 article in the Journal of Shellfish Research. They argue that fishermen turning to other species and areas unaffected by brown tide can cause overexploitation of those fisheries, thereby reducing the economic benefits derived from them.
Harmful algal blooms are an emerging focus of both international and national marine programs. The Intergovernment Oceanographic Commission has developed an International Harmful Bloom Program to coordinate training programs and encourage countries to start research, education, and outreach on the issue. A U.S. interagency task force - with representatives from the National Science Foundation, NOAA, the National Marine Fisheries Service, the Department of Defense, and other groups - has developed a research plan on harmful algal blooms. In addition, largely in response to the Brown Tide Comprehensive Management and Assessment Program, the U.S. Environmental Protection Agency established the Peconic Estuary Program, which is working on a comprehensive conservation and management plan to protect Peconic Bay's shellfish, vegetation, and rare or endangered species. "I'm impressed by the wealth of information on brown tide," Anne McElroy, New York Sea Grant director, said at the brown tide summit last fall. "But there's clearly a lot that still needs to be done to solve this issue."
New York State Assemblyman Fred Thiele reminded scientists at the summit that the people of Long Island were able to get $1.5 million from the state legislature to preserve the Pine Barrens. If the public rallies behind brown tide research, they might succeed in getting the money necessary to find a solution. "There's marine science and political science, and this project is going to be a little bit of both," said Thiele. "You have to articulate in a clear, concise way the benefits of brown tide research and how much it is going to cost, and you have to get the public behind it."
For more information on Brown Tide, follow this link.
Julie Zeidner is Communicator for New York Sea Grant.