BEHAVIORAL-RESPONSES OF MARKED SNAILS AS INDICATORS OF WATER-QUALITY

Behavioral responses of the common stream‐dwelling operculate snail Elimia clavaeformis were used to provide information about streamwater quality in in situ tests. These snails were found to be advantageous for such tests because they can be collected easily, individually marked, and transferred to other stream sites for release and recapture experiments. In noncontaminated stream sites, Elimia tended to disperse upstream. The rate of net movement was variable, but typically ranged from 0.5 to 5 m/d. Water velocity and food level influenced the movement patterns of the snails in 24‐ and 48‐h field experiments in noncontaminated stream sites. Rates of movement in the laboratory were temperature dependent, and increased from about 1.0 cm/min at 9°C to 2.2 cm/min at 24°C. In contaminated streams, snails showed clear evidence of stress: They moved downstream, and in some sites either withdrew into the shell or were unable to retract the foot or attach to a substrate. The maximum distance that Elimia traveled downstream in 24 h in a contaminated stream site was 17.5 m. In laboratory streams, Elimia moved downstream when exposed to 0.02 mg/L total residual chlorine (TRC); the time required to immobilize these snails declined rapidly as TRC concentration increased. Behavioral characteristics of snails that may be useful for water quality assessments include turnover time (the time needed for a snail to right itself after being turned onto its back), the rate and direction of dispersal or immobilization. Copyright © 1990 SETAC