CUR - The Council on Undergraduate Research

Exploring the Lethal and Sub-Lethal Effects of Pesticide Pollution on Freshwater Symbionts

Zachary Youngbar, Megan Pizzo, Cara Arrasmith, and Dr. Kyle Harris, Department of Biology and Chemistry, Liberty University, 1971 University Blvd. Lynchburg, VA 24515

Pesticides (e.g. herbicides and insecticides) are commonly applied to limit the abundance of target organisms (e.g. weedy plants or crop eating insects). However, with the abundance of pesticide application, these pesticides have the possibility to enter the surrounding ecosystems and come in contact with non-target organisms. Freshwater ecosystems near urban and agricultural development may have a higher occurrence of exposure to three common pesticides (e.g. Atrazine(ATZ), Glyphosate(GLY), and 2, 4-D) due to run-off events after rainfall. This study explores the impact of three of the most commonly used pesticides on crayfish along with crayfish annelid ectosymbionts called Branchiobdellidan worms(BW). Chronic exposure of juvenile crayfish to ATZ revealed stunted growth and degradation of hepatopancreas tissue. In addition, acute exposure of adult crayfish to ATZ, GLY, and 2, 4-D revealed significant hepatopancreas tissue degradation. Interestingly, while single treatments of ATZ and GLY did not result in BW mortality, the combined acute 48 hour treatments resulted in 100% mortality. BW survivors from the single GLY treatment also revealed significant tissue degradation. These results provide evidence to support the potential impact of environmentally relevant doses of common pesticides on common non-target freshwater organisms. Such evidence supports the need to control pesticides from entering aquatic ecosystems in an effort to conserve non-target species.

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