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United States Department of Agriculture

Agricultural Research Service

Title: Acetylcholinesterase Activity in Grass Shrimp and Aqueous Pesticide Levels from South Florida Drainage Canals

Authors
item Key, P. - NOAA
item Fulton, M. - NOAA
item Harman Fetcho, Jennifer
item Mcconnell, Laura

Submitted to: Archives of Environmental Contamination and Toxicology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 16, 2003
Publication Date: June 1, 2003
Citation: Key, P., Fulton, M., Harman-Fetcho, J.A., McConnell, L.L. 2003. Acetylcholinesterase activity in grass shrimp and aqueous pesticide levels from South Florida drainage canals. Archives Of Environmental Contamination And Toxicology. 45:371-377.

Interpretive Summary: Man-made, freshwater drainage canals are used in South Florida to manage water in agricultural, urban, and water conservation areas. These canals collect urban and agricultural storm runoff and discharge into the Atlantic Ocean and Gulf of Mexico. Certain pesticides called organophosphates are toxic because they cause a decrease in an important nervous system chemical called acetylcholinesterase (AChE). A collaborative study was conducted to determine pesticide levels in canal water and to measure AChE levels in native grass shrimp from the same locations. This preliminary study shows a statistically significant correlation between water samples in which organophospate pesticides were detected and in the reduction in the acetylcholinesterase enzyme in the grass shrimp exposed to water from the same location. While pesticide levels observed in this study were not high enough to cause the reduced AChE levels in the grass shrimp, these results indicate earlier exposures to organophosphate concentrations. The results suggest that monitoring organisms for AChE levels can be an effective means of detecting exposure to organophosphate contamination.

Technical Abstract: Freshwater drainage canals in South Florida are utilized to manage water in agricultural, urban, and water conservation areas and, as a result, collect urban and agricultural storm runoff that is discharged into the Atlantic Ocean and the Gulf of Mexico. Pesticides in this runoff may be toxic to the biota inhabiting these waters. This study evaluated the effects of contaminants in South Florida drainage canals on estuarine health using grass shrimp (Palaemonetes intermedius) as a representative invertebrate species. Results of surface water analysis for pesticides indicated that eight pesticides out of 52 analyzed were detected. The herbicide metolachlor was found at all nine sites in the five canals sampled at concentrations up to 119 ng/L. Three organophosphate (OP) insecticides (chlorpyrifos, malathion, diazinon) were detected at three sites in two canals (Military and North). Unlike other pollutants, OP's are generally considered to be irreversible inhibitors of acetylcholinesterase enzyme (AChE) because dephosphorylation of the bond enzyme proceeds at an insignificant rate. Grass shrimp from these three sites showed significantly reduced levels of AChE. While pesticide levels observed in this study were not high enough to cause this effect on the grass shrimp, these results indicate earlier exposures to organophosphate concentrations. The results suggest that monitoring organisms for AChE levels can be an effective means of detecting exposure to OP contamination.

Last Modified: 9/10/2014
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