Preliminary Tests on the Effects of Atrazine Exposure on the Food-Seeking Behaviors and Locomotion of Juvenile Virile Crayfish (Faxonius virilis)

The objective of this study was to conduct preliminary tests to determine if differing concentrations of atrazine affected locomotion and/or food-seeking behaviors of juvenile (second and third instar) virile crayfish after a 4-day (96 h) exposure period. After exposing crayfish to 0, 5, 10, 20, and 100 parts per billion (ppb) atrazine treatments, crayfish were tested and video-taped individually in a flow-through test arena before and during introduction of a food odor. Walking speeds (pre-odor, post-odor, and pre- to post-ratios), time to locate the food-odor source, and success rates in finding the food odor were compared among atrazine treatments. Pre-odor walking speeds, time to locate the food-odor source, and post-odor walking speeds did not differ among the control and treatment crayfish. Crayfish success rates in locating the food-odor source also did not differ among treatments and controls. Crayfish in controls and all atrazine treatments walked slightly, but not significantly, faster after a food odor was presented than before. Virile crayfish food-seeking behavior and locomotion were not affected after exposures up to 100 ppb atrazine, so these behaviors likely are not useful indicators of crayfish exposure to environmentally relevant (5 ppb or less) atrazine levels like those measured periodically in regional streams. Expanded replication and testing may be helpful in assessing the effects of atrazine (especially concentrations at or above 100 ppb) on the food-seeking behaviors of this species, although simple behavioral studies of crayfish may not be sensitive enough to assess the true effects of atrazine on aquatic organisms and communities.