Cholinesterases in Aquatic Biomonitoring Assay Op

Authors: Andrew Whitehead Susan L Anderson Alberto Ramirez Barry W Wilson

Publish Date: 2005/06/30

Volume: 14, Issue: 6, Pages: 597-606

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Abstract

Cholinesterase ChE enzyme activity measurements are widely applied in aquatic organisms for water quality monitoring especially for pesticide contamination in agricultural watersheds These biomarkers are amenable to measurement in a variety of species and are therefore useful for examining effects in model organisms relevant to the ecosystem of interest However extensive variation in ChE biochemistry exists among tissues and species This variation is rarely characterized and may lead to biases in the interpretation of activity determinations We optimized ChE activity measurement parameters and characterized ChE biochemistry in Sacramento sucker Catostomus occidentalis a widely distributed fish native to watersheds of the Central Valley of California Acetylcholinesterase AChE was the predominant ChE present in C occidentalis brain and muscle and muscle AChE was most sensitive to diazinon inhibition Field caging experiments indicated that exposures to ChEinhibiting pesticides were insufficient to induce neurotoxic effects However pesticide usage in the Central Valley is highly variable among years and longterm monitoring of instream effects would be necessary to evaluate trends in pesticide contamination Recent changes to the State Water Code require agricultural landowners to participate in a regional water quality monitoring plan As with most regional monitoring plans measurements of instream effects and effects in resident species are not scheduled to be included We suggest that inclusion of biomarker measures would lend important information to the monitoring process and propose these procedures as a template for adapting ChE activity measurements into regionspecific monitoring programs to assess instream effects of pesticide contamination on native speciesThanks to J Henderson for assistance in Ellman assay optimizations K Marlow W Rose J Machula E Moon and T McCrummen were of valuable assistance in executing laboratory and field experiments K Kuivila and J Orlando performed all analytical chemistry and were of great help in the field Special thanks to two anonymous reviewers for helpful comments on the manuscript A Whitehead is grateful for fellowship support from the Natural Sciences and Engineering Research Council NSERC of Canada and the University of California Toxic Substances Research and Teaching Program Lead Campus Program in Ecotoxicology This study was supported by a US Environmental Protection Agency EPA Science to Achieve Results STAR Grant 98NCERQAD1 awarded to S Anderson B May D Hinton and K Kuivila with additional support from the US Geological Survey Toxic Substances Hydrology Program Although this study has been funded in part by the US EPA it does not necessarily reflect the views of the Agency

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