Shelter-seeking behavior of crayfish, Procambarus clarkii, in elevated carbon dioxide

Carbon dioxide has been found to produce various negative consequences for a number of aquatic species and is projected to rise in the future for many aquatic ecosystems. Crayfish act as indicators of water quality and function as keystone species in aquatic food webs; however, there is a paucity of research on how crayfish may respond to elevated CO2. This study quantified how shelter-seeking behavior in freshwater crayfish (e.g., family Cambaridae), a behavior critical for survival and fitness, may change following exposure to elevated pCO(2). Red Swamp crayfish (Procambarus clarkii, Girard, 1852) were exposed to one of three potential levels of dissolved CO2 that could be found in freshwater basins currently or under future climate change conditions: Control (< 100 mu atm), Low (6853 +/- 1206 mu atm), and High (19,086 +/- 2043 mu atm) for 8 days, and were then transferred to a treatment aquarium with the same CO2 levels as the respective initial exposure. The treatment aquarium contained a shelter and was divided into three equal sections based on proximity to that shelter. Crayfish proximity to the shelter (defined by the tank sections) in the treatment aquarium was monitored every 5 s for a 2-min trial. Crayfish spent differing amounts of time in differing zones of the experiment and had different levels of activity, depending on their pCO(2) exposure; crayfish acclimated to High pCO(2) increased their time spent hiding and decreased their overall activity when compared to the Low pCO(2) and Control treatments. Augmented shelter-seeking behavior may affect crayfish social hierarchies, feeding, mating, and mortality, which could generate cascading effects on the ecology of many freshwater ecosystems.