An assessment of the embryotoxicity of cadmium in the terrestrial mollusk Cantareus aspersus: from bioaccumulation to impacts at different levels of biological organization.

This study aims to determine various parameters that allow the evaluation of the toxicity of chemicals to embryos of the ubiquitous land snail Cantareus aspersus. For this purpose, we investigated morphological and physiological endpoints in control embryos and in embryos exposed to a solution of 6mg Cd/L (CdCl2) in a liquid phase bioassay: size at days 3, 6 and 10, heart rate at 7 days, delay in hatching, states of development of non-hatched eggs after 17 days and the fresh mass of newly hatched embryos. The kinetics of Cd accumulation in eggs and DNA fragmentation were also measured. The first detectable sign of adverse effects appeared after 7 days of development, when the heart rate decreased in Cd-exposed embryos compared with the control. After 10 days of exposure, Cd-exposed hatchlings exhibited a lower fresh mass than control individuals. The majority (75 percent) of non-hatched embryos at 17 days was dead and presented signs of disaggregation or malformations. The hatching of Cd-exposed eggs was delayed 4 days, and DNA fragmentation was later detected after 20 days of Cd exposure. The measurement of Cd in the eggs showed that concentrations are relatively stable during the exposure period from 3 days (20-27µg Cd/g DW) to the end of exposure. The present study completes the range of endpoints that can be used to study the effects of contaminants and provides new parameters that are readily measured throughout the embryonic development of a terrestrial mollusk.