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Changes in Climate Could Make Pesticides More Toxic to Estuarine Organisms

In general, pesticides were found to be more toxic under more extreme conditions.

Charleston Harbor tidal creek

From Land to Sea

Pesticides enter our coastal waters after rain washes the chemicals into waterways that flow to the sea. Tidal creek ecosystems may be especially sensitive to environmental contamination from pesticides coupled with climate change. Shown here: tidal creek located within Charleston Harbor, S.C.

Changes in climate may influence pesticide toxicity in the coastal zone, according to a recent study by NOAA’s National Centers for Coastal Ocean Science (NCCOS). Pesticides enter our estuarine waters by runoff from land following a storm. These pesticides are used for agricultural, turf grass, home and garden, and mosquito control applications.

NCCOS researchers tested adult and larval grass shrimp, phytoplankton, and larval clams with pesticides commonly used to control insect, weed, and fungal pests. Next, scientists compared the toxicity of the chemicals using standard test conditions to the toxicity under climate stress conditions (e.g., higher temperature, higher salinity, lower oxygen, and lower pH). In general, it was found that pesticides were more toxic under more extreme conditions than under conventional testing conditions. The results from this study suggest that future risk assessments should take climate variables into account to determine the safety of pesticide use within the coastal zone.