Use of 65Zn to Determine the Field Metabolism of the Snail Cepaea nemoralis L.

Abstract

Zinc—65 elimination rates were measured in the laboratory for adult land snails, Cepaea nemoralis fed on carrot at 10°, 13°, 16°, and 22° and fed on a natural food material at 13°C, and for juveniles fed on carrot at 13°C. Ingestion, assimilation, production, and respiration were determined for each snail. Regressions between 65Zn loss and various aspects of metabolic activity were significant at each temperature except 22°C. For adult snails at 10°, 13°, and 16°C, excretion of the isotope was best related to weight of food ingested (r = 0.82), but respiration could also be predicted if temperature was known. The digestive gland contained 77% of the total body count, and its secretions were the principal means of 65Zn elimination. The loss of 65Zn under field conditions was used to estimate the amount of energy ingested, assimilated, and respired by adult snails over an annual cycle. Egg production did not involve an appreciable proportion of the total 65Zn loss.

Biological Monitoring of Heavy Metal Pollution

“…The trends in these data are similar to those demonstrated by data for the same metals in Cepaea hortensis collected from sites close to a major road (Williamson, 1979b). The general distribution of zinc in the samples of H. aspersa that were studied was similar to that reported for Zn-65 in Cepaea nemoralis (Williamson, 1975). Hence, Coughtrey and Martin (1976a) re-ported that the digestive gland of Helix aspersa was an important site for the accumulation of lead, zinc and cadmium; copper was shown to be more generally distributed throughout the body tissues.…”