Do crayfish (Orconectes virilis) recover from and acute atrazine exposure?

Kana, Maria, Noor Abraham, Lauren May, Lauren Mooney, Hung Nguyen, Tyler Peters, and Rachelle Belanger

Crayfish are a keystone species because they play a crucial role in the aquatic habitat due to their ability to transfer energy within the benthic food web and between the benthic and terrestrial food chains. Environmental contaminants such as the commonly used herbicide atrazine, is known to have a negative impact on olfactory-mediated behaviors in aquatic animals. Because crayfish rely heavily on their chemosensory reception to obtain food and mates and because they live in turbid environments, negative impacts on chemoreception could negatively affect population size. Prior research in our lab has shown that an acute atrazine exposure has damaging effects on olfactory-mediated behavioral responses to both food and mate odors in the crayfish O. rusticus.  What is not currently known is whether or not crayfish can recover any of their chemosensory abilities after this initial exposure or if the effects are long-term. Our research involved examining recovery of chemosensory abilities after exposure to sub-lethal, environmentally relevant concentrations of atrazine. Atrazine-treated crayfish (N=15) were exposed to 80 ppb (µg/L) atrazine for 96 hours. Control crayfish were exposed to water only for 96 hours. We then analyzed the ability of the crayfish to locate a food source using a Y-maze and fish flavored gelatin in one arm of the maze. A video tracking software was used to examine and compare time spent within 10 cm of the food source, time in correct arm of the maze, velocity, and time spent moving and not moving. We also examined total food consumed and total distance travelled in the tank. Next, we allowed the crayfish to recover for 24, 48 and 72 hours in fresh water. Every 24 hours, we re-examined the behavioral trials to determine if there were any changes in chemosensory-mediated behavior. Our data suggest that crayfish are not able to recover their chemosensory reception 72 hours post-atrazine exposure. For all times tested, control crayfish spend significantly more time in the arm with the food, near the odor source and consume more food than those crayfish exposed to atrazine. This is significant because a long-term reduction in chemosensory abilities can have lasting effects on foraging abilities and may thus impact population size.