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The influence of water level fluctuations and substratum drying on the survival and behaviour of an invasive freshwater snail Physa acuta Draparnaud, 1805
Pulmonate snails live in near-shore zones of waterbodies, experiencing water level fluctuations. In this study we investigated the resistance of Physa acuta to desiccation and its behavioural responses to drying: horizontal migrations and burrowing. Learning the adaptations of P. acuta to extreme ranges of environmental factors may be crucial for understanding its invasiveness. Survival in gradually drying sand was determined as LT50 and LT90 (time until death of 50 and 90% of individuals respectively). Horizontal migration was studied at shorter and longer distances (24 and 48 cm), with gradual or sudden (longer distance only) dewatering. Burrowing was studied during a gradual water level decrease. Snails were highly resistant to drying as their LT50 and LT90, on the exposed substratum, were 8 and 11 days respectively. They also exhibited horizontal migrations at shorter distances during gradual dewatering. Migration was less pronounced at the longer distance. After a sudden dewatering snail movement was limited, suggesting that they stayed passive rather than risked a migration over the exposed substratum. Snails never burrowed in sediments in response to dewatering. Resistance to drying and ability to migrate enables P. acuta to survive in harsh environments and can contribute to its invasiveness.
MF17349 Accepted 16 February 2018
© CSIRO 2018