The Influence of Hypoxic Conditions on Mating Behavior in a Bimodal Breather, the Great Pond Snail (Lymnaea stagnalis)

Reduced oxygen availability can become an environmental stressor that imposes constraints on the energy and/or time budget of aquatic animals. This also seems to be the case for bimodal breathers, since it was previously reported that the amount of oxygen in the water interacts with feeding and egg-laying activities. The great pond snail (Lymnaea stagnalis) is a typical bimodal breather and a simultaneous hermaphrodite for which both male and female mating behaviors have been studied in detail. The aim of this study was to test whether hypoxic conditions affect mating behavior in this bimodal breather and to investigate whether mating motivation and the choice of sexual role is influenced by this environmental condition. Our results show that when oxygen cannot be acquired via cutaneous respiration or aerial respiration, mating and locomotion are inhibited. When oxygen is available only via air, the occurrence of unilateral insemination, reciprocal insemination, and biting behavior is reduced and courtship duration is decreased compared to when oxygen is also available in the water. Our results indicate that depending on the oxygen availability in the environment, water, and air, this bimodal breather has to weigh its motivation to mate against its need for cutaneous and/or aerial respiration. These findings contribute to our understanding of how animals optimize their behavioral investment decisions under changing environmental circumstances.