Biological responses of the predatory blue crab and its hard clam prey to ocean acidification and low salinity

How ocean acidification (OA) interacts with other stressors is understudied, particularly for predators and prey. We assessed long-term exposure to decreased pH low salinity on (1) juvenile blue crab Callinectes sapidus claw pinch force, (2) hard clam Mercenaria mercenaria survival, growth, shell structure, (3) interactions in filmed mesocosm trials. In 2018 2019, we held crabs clams from the Chesapeake Bay, USA, crossed (low: 7.0, high: 8.0) 15, 30) treatments 11 10 wk, respectively. Afterwards, force ridge rugosity. Claw increased size both years but weakened pH. Clam growth was negative, indicative of dissolution, compared control. Growth also negative 2019 high-pH/low-salinity treatment. survival lowest low-pH/low-salinity treatment highest high-pH/high-salinity Shell damage rugosity (indicative deterioration) were intensified under negatively correlated survival. Overall, more severely affected by than crabs. predator-prey interactions, did not substantially alter behavior, spent time eating burying high-salinity moving low-salinity treatments. Given complex effects clams, projections about climate change will be difficult must consider multiple stressors.