NOAA Study Identifies Potential Impacts of Pesticide on Estuarine Health

Researchers with the National Oceanic & Atmospheric Administration's (NOAA) National Centers for Coastal Ocean Science have identified potential effects of the commonly used herbicide atrazine on phytoplankton -- free-floating algae forming the base of the food chain for aquatic animals. Published in the January issue of the journal Pesticide-Biochemistry and Physiology, the study indicates protein levels in phytoplankton significantly decreased as a result of atrazine exposure.

Research was conducted on five algal species exposed to atrazine levels within the range of atrazine concentrations that have been measured in the estuarine environment. In the majority of the species tested, the amount of energy converted into protein from photosynthesis significantly decreased. Photosynthesis is the process in green plants by which light energy is used to convert water and carbon dioxide into organic materials, producing oxygen as a byproduct.

Atrazine is one of the most heavily used herbicides in the United States. It acts as an inhibitor of photosynthesis by preventing the transfer of energy in certain plant species. NOAA researchers have observed significant decreases in size of phytoplankton species exposed to atrazine, which may negatively affect higher level species in the aquatic food chain as this crucial food source loses nutritional value.

"Many aquatic animals such as clams and oysters rely on phytoplankton as a food source," said Marie DeLorenzo, NOAA research ecologist. "Disruption to the cellular composition of phytoplankton species may negatively affect nutritional levels of the plant, resulting in decreased growth rates for those animals that consume phytoplankton."

Mike Fulton, a NOAA research fishery biologist, said that the use of atrazine as a growth inhibitor in broadleaf and grassy weeds is an accepted practice beneficial to farmers and landscape professionals. "But it is equally important to gain an understanding of the potential effects of this herbicide on non-target aquatic plant species," he said.

For more information, contact NOAA's National Centers for Coastal Ocean Science at

This article originally appeared in the 01/01/2007 issue of Environmental Protection.

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