Short-term hypoxia that lasts just a few days or even hours is a major threat for the marine ecosystems. The single effect of the human-induced levels of hypoxia and other anthropogenic impacts such as elevated pCO2 can reduce the ability of preys to detect their predators across taxa. Moreover, both processes, hypoxia and elevated pCO2, are expected to co-occur in certain habitats, but the synergic consequences of both processes and the ability of fish to recover remain unknown. To provide empirical evidence to this synergy, we experimentally evaluated the risk-taking behavior in juveniles of the European seabass (Dicentrachus labrax), an important commercial fisheries species after recovering from short-term hypoxia and different pH scenarios. The behavior of seabass juveniles was monitored in an experimental arena before and after the exposure to a simulated predator and contrasted to control fish (BACI design) (current levels of hypoxia and elevated pCO2) using a mechanistic function-valued modeling trait approach. Results revealed that fish recovering from elevated pCO2, alone or combined with hypoxia, presented less avoidance behavior in failing to seek refuge when a simulated predator was present in the arena compared to those exposed to control pCO2 levels. Our results show that recovery from short-term exposure to acidification and hypoxia was not synergistic and suggest that recovery from acidification takes longer than from short-term hypoxia treatment through a potential effect on the sensorial and hence behavioral capacities of fish.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This is a contribution to the projects MedSeA of the FP7 of the EU (contract no. FP7-ENV-2010-265103) and ESTRESX (ref. CTM2012-32603), funded by the Spanish ministry of economy and competitivity. AS was funded by a Ph.D. fellowship from the Government of the Balearic Islands (Department on Education, Culture, and Universities) and the EU (European Social Fund) as well as King Abdullah University of Science and Technology. CD-G was funded by a fellowship from the National Institute for Agricultural and Food Research and Technology (INIA). JA was supported by a JdC post-doc grant funded by the Spanish Ministry of Economy, Industry and Competitiveness (ref. IJCI-2016-27681). IC thanks the funding of CERES H2020 project (BG-02-2015, 678193). We thank I.E. Hendriks and Miquel Palmer for advice, and Culmarex Group for providing European Sea Bass specimens.