Tolerance of juvenile Mytilus galloprovincialis to experimental seawater acidification

Coastal ocean acidification is expected to interfere with the physiology of marine bivalves.In this work, the effects of acidification on the physiology of juvenile mussels Mytilus galloprovincialis were tested by means of controlled CO 2 perturbation experiments.The carbonate chemistry of natural (control) seawater was manipulated by injecting CO 2 to attain 2 reduced pH levels: -0.3 and -0.6 pH units as compared with the control seawater.After 78 d of exposure, we found that the absorption efficiency and ammonium excretion rate of juveniles were inversely related to pH.Significant differences among treatments were not observed in clearance, ingestion and respiration rates.Coherently, the maximal scope for growth and tissue dry weight were observed in mussels exposed to the pH reduction ΔpH = -0.6,suggesting that M. galloprovincialis could be tolerant to CO 2 acidification, at least in the highly alkaline coastal waters of Ria Formosa (SW Portugal).