Adaptation and acclimatization to ocean acidification in marine ectotherms: an in situ transplant experiment with polychaetes at a shallow CO 2 vent system

Abstract

Metabolic rate determines the physiological and life-history performances of ectotherms. Thus, the extent to which such rates are sensitive and plastic to environmental perturbation is central to an organism's ability to function in a changing environment. Little is known of long-term metabolic plasticity and potential for metabolic adaptation in marine ectotherms exposed to elevated p CO 2 . Consequently, we carried out a series of in situ transplant experiments using a number of tolerant and sensitive polychaete species living around a natural CO 2 vent system. Here, we show that a marine metazoan (i.e. Platynereis dumerilii ) was able to adapt to chronic and elevated levels of p CO 2 . The vent population of P. dumerilii was physiologically and genetically different from nearby populations that experience low p CO 2 , as well as smaller in body size. By contrast, different populations of Amphiglena mediterranea showed marked physiological plasticity indicating that adaptation or acclimatization are both viable strategies for the successful colonization of elevated p CO 2 environments. In addition, sensitive species showed either a reduced or increased metabolism when exposed acutely to elevated p CO 2 . Our findings may help explain, from a metabolic perspective, the occurrence of past mass extinction, as well as shed light on alternative pathways of resilience in species facing ongoing ocean acidification.