Effects of atrazine on virilis crayfish (Orconectes virilis) agonistic behavior

Abstract

Atrazine is an herbicide that has been intensively used in the Great Lakes basin for about 25 years and has a long half-life in cold, low productive aquatic systems (Schottler and Eisenreich1997). Atrazine has been increasingly found in drinking water and has been proven to impact aquatic flora and fauna (Guasch 1997). One of the organisms possibly affected by this chemical is crayfish. Crayfish are considered to be a keystone specie to Michigan aquatic ecosystems due to their feeding habits and the food source they provide to predators. Previous studies suggest that crayfish species have been negatively affected by the addition of atrazine to waterways because it inhibits their olfactory and chemoreceptor processes. For th is study we subjected female Orconectes virilis crayfish to short term exposure of atrazine within a artificial dynamic stream system. We believe that the short term atrazine will affect the agonistic behavior by being out performed by their nativeve counterparts. After a 24 hour period, the crayfish were placed in 5 minute bouts and scored on both passive and aggressive actions. From our results, we did not find any significant differences in the agonistic behavior of control and esposed groups of crayfish. AIthough we could not see the impact of acute exposure of atrazine on agonistic behavior, prior studies have longer exposure has negatively impacted behavior and reproduction. This in combination with our study may suggest that acute exposure to atrazine is less harmful to stream ecosystems.