Transgenerational responses of molluscs and echinoderms to changing ocean conditions

We are beginning to understand how the larvae of molluscs and echinoderms with complex life cycles will be affected by climate change. Early experiments using short-term exposures suggested that larvae in oceans predicted to increase in acidification and temperature will be smaller in size, take longer to develop, and have a greater incidence of abnormal development. More realistic experiments which factored in the complex life cycles of molluscs and echinoderms found impacts not as severe as predicted. This is because the performance of one life history stage led to a significant carryover effect on the subsequent life history stage. Carryover effects that arise within a generation, for example, embryonic and larval stages, can influence juvenile and adult success. Carryover effects can also arise across a generation, known as transgenerational plasticity (TGP). A transgenerational response or TGP can be defined as a phenotypic change in offspring in response to the environmental stress experienced by a parent before fertilization. In the small number of experiments which have measured the transgenerational response of molluscs and echinoderms to elevated CO2, TGP has been observed in the larval offspring. If we are to safeguard ecological and economically significant mollusc and echinoderm species against climate change then we require more knowledge of the impacts that carryover effects have within and across generations as well as an understanding of the underlying mechanisms responsible for such adaptation.