New research indicates that commonly-used insecticide mixtures continue to impact aquatic invertebrate species over multiple weeks, even when the chemicals are no longer detectable in water.
Through experiments meant to generally reflect runoff from a multiple-homeowner watershed, investigators found that pesticide mixtures had negative effects on the abundance of certain snails, water fleas, and crustaceans.
"The effects we observed indicate that many species were affected at a sublethal level," said Dr. Simone Hasenbein, lead author of the Environmental Toxicology & Chemistry study.
"Thus, populations exposed to low concentrations of pesticides could be even more sensitive to other abiotic or biotic factors such as invasive species, or changes in salinity or temperature leading to a magnification of multi-stressor situations."
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Simone Hasenbein et al. A long-term assessment of pesticide mixture effects on aquatic invertebrate communities, Environmental Toxicology and Chemistry (2015). DOI: 10.1002/etc.3187