Examining the long-term recovery of chemoreception in crayfish (Orconectes virilis) following an acute atrazine exposure

May, Lauren, Kaldoun Barawi, Hung Nguyen, Lauren Mooney, and Rachelle Belanger

Atrazine was first introduced in the 1950s to increase production of field corn, sorghum and sugarcane and is now one of the most commonly used herbicides in the United States. We have previously shown that exposure to an environmentally relevant concentration of atrazine causes deleterious effects in the chemosensory responses of crayfish to both food odors and mate odors. Additionally, crayfish could not recover these chemosensory responses following a 72-hour recovery period in clean water. Crayfish are nocturnally active and often found in turbid environments. Given this, they rely extensively on waterborne odors for locating mates, food and shelters as well as to avoid predators. In this study, crayfish (Orconectes virilis) were exposed to atrazine (80 ppb for 96 hours) and recovery was examined over a 15-day period. After treating the crayfish, a Y-maze was used and fish-flavored gelatin was placed in one arm while control gelatin was placed in the other. Time spent in the food arm of the Y-maze, time at the odor source, walking speed and the total amount of food consumed during the 15-day recovery period were examined every three days. Upon analysis, preliminary data indicated some recovery was possible after approximately nine days in fresh water. Results from this experiment are important because crayfish are polytrophic, meaning they feed on and become prey for all levels of the aquatic food web. Additionally, crayfish facilitate the transfer of energy between benthic and terrestrial food webs. Since crayfish rely heavily on their chemosensory abilities to acquire food, the long-term impacts of atrazine exposure could affect population size in areas where atrazine is heavily applied. Any reduction in crayfish population size will, in turn, affect aquatic food web dynamics.