Resistance of juveniles of the Mediterranean pen shell, (Pinna nobilis) to hypoxia and interaction with warming

Low oxygen zones in coastal and open ecosystems have expanded in recent decades, a trend that will accelerate with climatic warming. Exposure of nearshore animals to hypoxic waters and increasing temperature may be stressful and lead to impaired physiological performance. Here, we evaluate the effect of low oxygen concentrations in interaction with increased temperature on juveniles of a large Mediterranean bivalve, Pinna nobilis. We examine the response of survival and oxygen consumption of juveniles placed in water with normal and low oxygen concentrations (100% and 40%, respectively) along an increased temperature gradient (24, 26, 28 and 30 °C) during 4 days. To our knowledge, this is the first study on hypoxia and its combined effect with temperature on juveniles of this species. We show that the two stressors alone or in combination do not influence the physiological performance of juveniles for short periods (4 days). This result stands apart from a general trend pointing at ocean warming as additional stressor that could increase the vulnerability of benthic macrofauna to reduced oxygen concentrations.This research was supported by the MedSeA project (www.medsea-project.eu, contract number 265103 of the Framework Program 7 of the European Union), and ESTRESX (ref. CTM2012-32603), funded by the Spanish Ministry of Economy and Competitiveness. L. Basso was supported by JAE pre-DOC fellowship and I.E.H. by a JAE-DOC fellowship (CSIC, Spain). Alexandra Steckbauer was funded by a fellowship from the Government of the Balearic Islands (Department on Education, Culture and Universities) and the EU (European Social Fund)Peer Reviewe