Movement and burrowing of Helisoma trivolvis (Say) (Gastropoda, Planorbidae) in a small pond

Abstract

The movement of 120 marked Helisoma trivolvis (Say) (Gastropoda, Planorbidae) was followed for up to 26 days in a shallow, 0.75-ha pond in southern Ontario during the autumn of 1970. At water temperatures of 7–15 °C, the mean and maximum rates of dispersal were 1.4 and 19.2 cm/h, respectively. One snail moved 18.3 m in 26 days. The snails burrowed 1–2 cm into the bottom of the pond and remained burrowed for up to 45 h. The percentage of the snails which burrowed into the mud seemed to increase as the water became colder. No evidence could be found of either an autumn migration to deeper water or the occurrence of a homing behavior. The snails moved freely throughout the pond at all times of the year except when movement was curtailed by cold temperature. The rate of dispersal of lentic snails seems not to differ from that of lotic snails.