Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Effects of water level fluctuations and substratum drying on the survival and behaviour of the invasive freshwater snail Physa acuta Draparnaud, 1805.

Abstract

Pulmonate snails live in nearshore zones of waterbodies, experiencing water level fluctuations. In the present study we investigated the resistance of Physa acuta to desiccation and its behavioural responses (horizontal migrations and burrowing) to drying. Determining 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 (i.e. the 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 decrease in water level. Snails were highly resistant to drying as the LT50 and LT90 values on the exposed substratum were 8 and 11 days respectively. In addition, snails 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 the snails 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.