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From April 5, 2005

Study Reveals Common Pesticides Damage Aquatic Communities
(Beyond Pesticides, April 5, 2005)
The study, The impact of insecticides and herbicides on the biodiversity and productivity of aquatic communities, confirmed that four common pesticides, Sevin® (carbaryl), malathion, RoundUp® (glyphosate), and 2,4-D are harmful to aquatic populations. In particular RoundUp® proved to be highly toxic to amphibians, decreasing their populations by nearly 70%.

Professor Rick Relyea, of the University of Pittsburgh, conducted the study, which is published the April 2005 issue of Ecological Applications. His findings are important in understanding the comprehensive impact that these chemicals have in real world scenario. Dr. Relyea studied the impact of typical dosages on ecologically relevant aquatic species and found that Sevin® reduced species richness (a measure of population size and interactions) by 15%, malathion by 30%, RoundUp® by 22%, and 2,4-D had no impact on species richness.

When looking at the impacts of these chemicals individually, Dr. Relyea found that RoundUp® was highly toxic to amphibians. These findings confirm other studies on amphibians and reproductive effects. However, in this study death occurred completely eliminating two species of tadpoles and a 70% decrease in the entire tadpole population.

According to The University of Pittsburgh Medical Center, Dr. Relyea initially wanted to see whether the Roundup® would have an indirect effect on the frogs by killing their food source, algae. However, he found that since it killed the frogs, the algae populations increased with no predators available to control it.

The most lethal ingredient in RoundUp® is its surfactant rather than its active ingredient (glyphosate) reports The University of Pittsburgh Medical Center, which allows the pesticide to penetrate the outer waxy layer of weeds. The other pesticides in the study have less potent surfactants, explaining RoundUp®’s greater impact in this study.

TAKE ACTION: Avoiding using herbicides and insecticides on your lawn, which can leach into groundwater and run-off contaminating aquatic ecosystems. See our alternatives factsheet to find environmentally safe alternatives.