Effects of elevated carbon dioxide and temperature on locomotion and the repeatability of lateralization in a keystone marine mollusc.

Recent work has shown that the behaviour of marine organisms can be affected by elevated P CO2 , although little is known about the effect of multiple stressors. We therefore investigated the effect of elevated P CO2  and temperature on locomotion and behaviour during prey searching in the marine gastropod Concholepas concholepas , a predator characteristic of the southeastern Pacific coast. Movement duration, decision time, route finding and lateralization were measured using a T-maze tank with a prey positioned behind a barrier. Four treatments, representing present day and near-future scenarios of ocean acidification and warming were used in rearing the individuals for 6 months. Regardless of the treatment, no significant differences were found in relative and absolute lateralization before and after exposure for 6 months. However, relative lateralization was not repeatable for animals tested after 6 months at elevated P CO2  at both experimental temperatures, whereas it was repeatable in individuals kept at the present day level of P CO2 We suggest that these effects may be related to a behavioural malfunction caused by elevated P CO2 Movement duration, decision time and route finding were not repeatable. However, movement duration and decision time increased and route finding decreased in elevated P CO2  (at 15°C), suggesting that elevated P CO2  has negative effects on the locomotor and sensory performance of C. concholepas in the presence of a prey odour, thereby decreasing their ability to forage efficiently.