Antioxidant Efficiency ofPlatynereisspp. (Annelida, Nereididae) under Different pH Conditions at a CO2 Vent’s System

Marine organisms are exposed to a pH decrease and to alteration of carbonate chemistry due to ocean acidification (OA) that can represent a source of oxidative stress which can significantly affect their antioxidant defence systems efficiency. The polychaetesPlatynereis dumeriliiandP. massiliensis(Nereididae) are key species of the benthic community to investigate the effect of OA due to their physiological and ecological characteristics that enable them to persist even in naturally acidified CO2vent systems. Previous studies have documented the ability of these species to adapt to OA after short- and long-term translocation experiments, but no one has ever evaluated the basal antioxidant system efficiency comparing populations permanently living in habitat characterized by different pH conditions (acidifiedvs.control). Here, individuals of bothPlatynereisspecies, sampled from a natural CO2vent system and from a nonventing “control” site in three different periods (April 2016, October 2016, and February 2017), were compared highlighting signals which suggested the ability of both species to acclimatize to highpCO2–low pH with slight seasonal variations of their antioxidant efficiency and the absence of disturbances of the oxidative status ofPlatynereisspp. tissues.