Impacts of ocean acidification and mitigative hydrated lime addition on Pacific oyster larvae: implications for shellfish aquaculture

Anthropogenic CO2 emissions are rapidly altering marine chemistry, significantly impacting calcifying organisms’ ability to produce and maintain shells. In the Pacific Northwest, shellfish hatcheries have already observed mass die offs of larvae, potentially from ocean acidification. This study aims to elucidate if hydrated lime can be used at the hatchery level to chemically reverse ocean acidification and its negative impacts on larval stages of the Pacific oyster, Crassostrea gigas. For 24 days, larvae were exposed to four treatments: ambient - 390 ppm, ocean acidified - 1500 ppm, limed-ambient and limed-ocean acidified treatments to meet pre-industrial levels ~ 280 ppm. Hydrated lime significantly increased larval shell length after two weeks of development, but did not affect survival or percent abnormality between treatments. Investigations into mitigative lime use appear cost effective and feasible for shellfish hatcheries under future CO2 scenarios, but requires more extensive research at the hatchery level, and for other species.