Manila clams (Ruditapes philippinarum) are an economically valued bivalve species that are the target of a valuable global aquaculture industry. As ocean acidification (OA) increases, bivalves like Manila clams and the calcium carbonate structures they utilize are threatened by ongoing changes in carbonate chemistry. Investigations into specific impacts of acidification on clams and other environmentally and economically important bivalves have revealed that acidic conditions reduced larval growth, settlement rates, shell thickness and adult growth. Parental priming is one method that can be used to combat these impacts and maintain or improve growth in an aquaculture setting. As a first step to evaluating the physiological influence of environmental perturbation on clam offspring it is valuable to understand how parental gametes are impacted.
This study uses transcriptomics to evaluate differences in egg gene expression to investigate the impacts of OA conditions on unfertilized eggs from Manila clam parents reared in acidic (pH 7.4) and ambient (pH ~7.8) conditions. Forty-six differentially expressed genes were identified in a preliminary analysis with a majority of them expressed at a lower level in eggs from clams in low pH conditions. Interestingly, biological processes associated with these genes include protein transport and processing, immune responses, developmental processes, as well as metabolic activities like glycolysis. These results suggest an impact on resource allocation and future studies should be designed to evaluate how this translates into offspring performance.