Temperature and salinity effects on the toxicity of common pesticides to the grass shrimp, Palaemonetes pugio

Abstract

This study investigated the effects of increased temperature and salinity, two potential impacts of global climate change, on the toxicity of two common pesticides to the estuarine grass shrimp, Palaemonetes pugio. Larval and adult grass shrimp were exposed to the fungicide chlorothalonil and the insecticide Scourge® under standard toxicity test conditions, a 10°C increase in temperature, a 10 ppt increase in salinity, and a combined increased temperature and salinity exposure. Toxicity of the fungicide chlorothalonil increased with temperature and salinity. Toxicity of the insecticide Scourge® also increased with temperature; while increased salinity reduced Scourge® toxicity, but only in adult shrimp. These findings suggest that changes in temperature and salinity may alter the toxicity of certain pesticides, and that the nature of the effect will depend on both the organism's life stage and the chemical contaminant. Standard toxicity bioassays may not be predictive of actual pesticide toxicity under variable environmental conditions, and testing under a wider range of exposure conditions could improve the accuracy of chemical risk assessments.

Keywords:

• Climate change
• pesticides
• toxicity
• estuaries
• shrimp

Acknowledgments

We thank Katy Chung, Alex Hoopai, and Joe Jutzi for assistance with grass shrimp collection, culture and testing. We appreciate Paul Pennington, Pete Key, and Michael Fulton for providing input and advice on the manuscript. Funding for this research was provided by National Oceanic and Atmospheric Administration (NOAA), National Science Foundation REU Site Award DBI-0552828, and the Department of Defense ASSURE Program. The National Ocean Service (NOS) does not approve, recommend, or endorse any proprietary product or material mentioned in this publication.