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Abstract. These experiments are part of a larger study designed to investigate the influence of husbandry parameters on the life history of the apple snail, Marisa cornuarietis. The overall objective of the program is to identify suitable husbandry conditions for maintaining multigeneration populations of this species in the laboratory for use in ecotoxicological testing. In this article, we focus on the effects of photoperiod, temperature, and population density on adult fecundity and juvenile growth. Increasing photoperiod from 12 to 16 h of light per day had no effect on adult fecundity or egg hatching and relatively minor effects on juvenile growth and development. Rearing snails at temperatures between 221C and 281C did not influence the rates of egg production or egg clutch size. However, the rates of growth and development (of eggs and juveniles) increased with increasing temperature in this range, and when temperatures were reduced to 221C egg-hatching success was impaired. Juvenile growth and development were more sensitive to rearing density than adult fecundity traits. On the basis of the present results, we conclude that rearing individuals of M. cornuarietis at a temperature of 251C, a photoperiod of 12L:12D, and a density of o0.8 snails L À1 (with lower densities for juvenile snails) should provide favorable husbandry conditions for maintaining multi-generation populations of this species.

Recent work on the snail Marisa cornuarietis has claimed to show endocrine disruption in response to bisphenol A (BPA). The present experimental design was optimized to detect effects of BPA on fecundity, egg hatchability, and juvenile growth, with an emphasis on reproduction, since previous studies suggested this to be a sensitive endpoint. No differences in eggs/female/ month between unexposed snails and snails exposed to nominal concentrations of 0.1, 1, 25, and 640 microg BPA/L during six months of exposure were found. No effect of BPA on the percentage of eggs hatching successfully was found, as was no difference in time to hatching between the control and any BPA treatment. We observed a significant decrease in female growth and a marginal effect on female wet weight in the 640-microg/L treatment compared to the control and a significant increase in male growth rate and a marginal increase in male wet weight in the 1-microg/L treatment compared to the control. However, a much greater proportion of the variability in juvenile growth was explained by variation between pairs and between siblings from the same pair than by BPA treatment. We conclude that effects of BPA in the nominal exposure range 0.1 to 640 microg/L (measured range 0.062-696 microg/L) are unlikely to be of significance for field populations of this species. An additional adult fecundity trial at 22 degrees C (in contrast to all other experiments that were conducted at 25 degrees C) found no evidence to suggest that snails are more sensitive to BPA at the lower temperature, as has been previously claimed. The present results indicate that the sensitivity of M. cornuarietis to BPA is similar to that of other aquatic invertebrates for which data are available.

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