Multigenerational Effects of Acidification on Early Life-Stage Mercenaria mercenaria (=hard clam)

While the effects of ocean acidification on marine bivalve molluscs have been well-studied, most investigations have failed to consider the multigenerational effects of this process. Under ecologically relevant climate change scenarios, bivalves will undergo reproductive conditioning in acidified environments, particularly in estuaries that are net heterotrophic and already subjected to acidification processes. Identifying the multigenerational effects of climate change is crucial for understanding impacts on marine ecosystems as transgenerational acclimation over time may provide a means to adapt to changing environments. The objectives of this research were, therefore, to identify the multigenerational effects of acidification on populations of the northern quahog, Mercenaria mercenaria. Adults were exposed to low (~7.3) and ambient pH (~7.9) during reproductive conditioning (8 weeks) and larvae originating from these adults were subsequently exposed to either low or ambient pH conditions. Survival, development, and growth were assessed during the entire larval phase. Results indicate that larvae originating from adults undergoing reproductive conditioning in acidified environments are more sensitive to low pH environments themselves, suggesting that the impacts of acidification on M. mercenaria larvae may become more severe over multiple generations as ocean acidification persists.