Brown Tide Research Initiative

ISSUE

Brown Tide, a microalgal bloom, was first reported in the bays of eastern Long Island, NY, in June 1985. By mid-summer of that year, it was clear that this organism resulted in the recruitment failure of scallops in the Peconic Bay system. Another bloom and scallop failure occurred in the summer of 1986. Although the brown tide organism, Aureococcus anophagefferens, was detectable in Long Island waters in following years, blooms on the order of those in 1985/86 did not occur. However, in the summer of 1995, an intense brown tide bloom returned. In response to this problem and public concern, the COP has initiated a coordinated program to understand and predict the onset of brown tide blooms, and advance strategies for mitigating its environmental impacts.

More generally, harmful algal blooms (HABs) stand out as one of the most scientifically complex and nationally relevant. In addition to Long Island, virtually every coastal state has reported major blooms. These blooms may be responsible for more than $1 billion in national losses. Harmful algal blooms can cause human illness and death, alter marine habitats through shading and overgrowth, adversely impact fish and other marine organisms, and close many coastal businesses.

APPROACH

A primary goal of this research is to develop a predictive capability based on an understanding of how physical and biological processes interact to promote bloom development, affect bloom dominance, and contribute to bloom maintenance or decline. Knowing the causes of these blooms will lead to identifying means to prevent them. Research is focused on: 1) isolating the organism which is an important prerequisite for further study; 2) identifying the factors that cause, maintain, and dissipate blooms; and 3) determining the genetic diversity of the organism which could lead to subsequent control strategies.

ACCOMPLISHMENTS

Preliminary research indicates that there may be several possible growth factors and ecological influences contributing to bloom development in Long Island. These factors include:

Brown tide organisms can grow when other phytoplantkton cannot - Aureococcus appears to have unique nutritional requirements and adaptive capabilities allowing it to out-compete and even overwhelm other algal species. Unlike many other species which predominately use inorganic (i.e., fertilizers) nutrients, Aureococcus can use organic nutrients.

Aureococcus is not generally eaten by other organisms - Data collected during the 1985-87 Narragansett Bay bloom showed that a significant decrease in the number of grazing organisms (i.e., predators of Aureococcus and other phytoplankton) was an important factor in the intensity and duration of that bloom. Smaller, more localized blooms observed in the Peconic Estuary, may be the result of local changes in the population of these grazing organisms.

Climate variability may be a factor - Brown tide events also appear to be influenced by regional climate variability. For instance, variations in precipitation will influence runoff and groundwater discharge and flow, all of which factor into the loading of nutrients, trace metals, and other growth stimulators (or inhibitors) to coastal waters.

MANAGEMENT AND POLICY IMPLICATIONS

Harmful algal blooms are increasing in number and intensity in U.S. coastal waters, generating serious problems for fishing, tourism, and human health. Because so little is known about the causes of HABs, responses have been cautious and often fragmented. NOAA's Coastal Ocean Program, in collaboration with the New York Sea Grant Program, have implemented efforts to improve management strategies for effectively reducing HAB effects. Research findings are being fed directly to the Suffolk County Health Department and the Peconic Estuary Program which are responsible for developing management measures.

Related Websites

For more information, contact:

Susan Banahan
CSCOR/Coastal Ocean Program
phone: 301-713-3338
e-mail: coastalocean@noaa.gov

Last Updated: October 23, 2002