Differential sensitivity of larvae to ocean acidification in two interacting mollusc species.

Anthropogenically-induced ocean acidification (OA) scenarios of decreased pH and altered carbonate chemistry are threatening the fitness of coastal species and hence near-shore ecosystems' biodiversity. Differential tolerances to OA between species at different trophic levels, for example, may alter species interactions and impact community stability. Here we evaluate the effect of OA on the larval stages of the rock oyster, Saccostrea cucullata, a dominant Indo-Pacific ecosystem engineer, and its key predator, the whelk, Reishia clavigera. pH as low as 7.4 had no significant effect on mortality, abnormality or growth of oyster larvae, whereas whelk larvae exposed to pH 7.4 experienced increased mortality (up to ∼30%), abnormalities (up to 60%) and ∼3 times higher metabolic rates compared to controls. Although these impacts' long-term consequences are yet to be investigated, greater vulnerability of whelk larvae to OA could impact predation rates on intertidal rocky shores, and have implications for subsequent community dynamics.