Research Product

Components of the Spartina alterniflora salt marsh were exposed to atrazine individually, in microecosystems, and in the field, to determine its effects on salt marsh components and its fate in the salt marsh. Components studied were S. alterniflora; horse mussel, Geukensia demissa; periwinkle snail, Littorina irrorata; box crab, Sesarma cinereum; fiddler crab, Uca pugnax; diatom spp, including Nitzschia sigma and Thallassiosira fluviatilis; detritivores, soil, and tidal water. Only algae were affected by possible contaminant concentrations (0.01 ppm) in seawater in the marsh. S. alterniflora was fairly tolerant but 0.1 ppm decreased growth slightly. Adult U. pugnax at their most sensitive stage may have been slightly affected by the 100 ppm. S. cinereum was unaffected when fed leaves from S. alterniflora grown in nutrient solution containing 0.6 ppm atrazine. Conversion to detritus was unaffected when S. alterniflora leaves were wetted with 0.26 ppm atrazine solution. No effects on snails or mussels were detected when the marsh was sprayed with 5 g/m2 atrazine. Atrazine was metabolized by S. alterniflora, S. cinereum, U. pugnax, and detritivores. Three months after atrazine application to the marsh the total herbicide remaining in the soil, S. alterniflora, L. irrorata, U. pugnax, and G. demissa was less that 3% of that applied. Seventy days after atrazine application to microecosystems, 50% had removed in tidal water; 42% within the first 6 days.