Lethal Consequences and Embryo Shell Shape Alterations in the Marine Gastropod Trophon geversianus Due to Elevated Temperatures

Environmental temperature is increasing while natural populations are forced to adjust their life cycle to new conditions, resulting in the expression of new phenotypic traits. Still, the links between these new environmental conditions and the subsequent phenotypic expressions are not fully explored. Here, we conducted manipulative experiments with embryos of the marine gastropod Trophon geversianus to assess the effects of warmer temperatures upon shell form. We observed lethal effects together with alterations in the shell form (size + shape) of embryos exposed to 18°C water compared to the control temperature environment (13°C). Our results reveal that T. geversianus from Patagonian coasts growing under warm temperatures will change their phenotype by developing smaller and more elongated shells during ontogeny, as well as an expanded shell aperture, increasing their predation vulnerability. Therefore, we consider that the embryonic shell shape change could be a good biomarker of thermal stress produced at early developmental stages in marine gastropods.