The influence of elevated seawater pCO2 on growth, calcification and maintenance of acid-base equilibria in the cephalopod Sepia officinalis.

The cuttlefish Sepia officinalis (cephalopod mollusc) appears to be more tolerant to ocean acidification conditions compared to more hypometabolic invertebrates. It is concluded that the cuttlefish ecotype is not only an efficient acid-base regulator, but is also able to do so without disturbing metabolic equilibria in characteristic tissues. S. officinalis maintains control growth rates during six-week exposure to 0.6 kPa CO2, however, in contrast to most invertebrates, the calcification rate of the cuttlebone increases. The maintenance of calcification during exposure to elevated seawater pCO2 is attributed to strong ion regulatory abilities. Our results are in line with existing studies that have found higher sensitivity to elevated seawater pCO2 of early life stages compared to juveniles and adults. Assessment of ecologically relevant species sensitivity cannot yet be performed. Experiments crossing the generation boundary are missing, as well as a finer resolution of potential repartitioning of the energy budget and closer examination of the influence of ultrastructural changes on cuttlebone function as a buoyancy regulation device.