Suchergebnisse

Coastal hypoxia is a problem that is predicted to increase rapidly in the future. At the same time, we are facing rising atmospheric CO2 concentrations, which are increasing the $\textit{p}$CO2 and acidity of coastal waters. These two drivers are well studied in isolation; however, the coupling of low O2 and pH is likely to provide a more significant respiratory challenge for slow moving and sessile invertebrates than is currently predicted. The Gullmar Fjord in Sweden is home to a range of habitats, such as sand and mud flats, seagrass beds, exposed and protected shorelines and rocky bottoms. Moreover, it has a history of both natural and anthropogenically enhanced hypoxia as well as North Sea upwelling, where salty water reaches the surface towards the end of summer and early autumn. A total of 11 species (Crustacean, Chordate, Echinoderm and Mollusc) of these ecosystems were exposed to four different treatments (high or low oxygen and low or high CO2; varying $\textit{p}$CO2 of 450 and 1300Ä '¬Î¼atm and O2 concentrations of 2-3.5 and 9-10Ä '¬mgÄ '¬LÄ '1) and respiration measured after 3 and 6 days, respectively. This allowed us to evaluate respiration responses of species of contrasting habitats to single and multiple stressors. Results show that respiratory responses were highly species specific as we observed both synergetic as well as antagonistic responses, and neither phylum nor habitat explained trends in respiratory responses. Management plans should avoid the generalized assumption that combined stressors will result in multiplicative effects and focus attention on alleviating hypoxia in the region. ; This research was funded by the project ASSEMBLE (grant agreement no. 227799; under the EU Research Infrastructure Action FP7) and the Estres-X project funded by the Spanish Ministry of Economy and Competitiveness (CTM2012-32603). Aisling Fontanini was funded by the School of Plant Biology at the University of Western Australia (grant 10300374) and 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) as well as King Abdullah University of Science and Technology. Sam Dupont is funded by the Linnaeus Centre for Marine evolutionary Biology at the University of Gothenburg and supported by a Linnaeus grant from the Swedish research Councils VR and Formas. We thank Karen Chan, Pia Engström and Julia Dombrowski for their assistance.

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. ; 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.

Ocean acidification (OA) and hypoxic events are an increasing worldwide problem, but the synergetic effects of these factors are seldom explored. However, this synergetic occurrence of stressors is prevalent. The coastline of Chile not only suffers from coastal hypoxia but the cold, oxygen-poor waters in upwelling events are also supersaturated in CO, a study site to explore the combined effect of OA and hypoxia. We experimentally evaluated the metabolic response of different invertebrate species (2 anthozoans, 9 molluscs, 4 crustaceans, 2 echinoderms) of the coastline of central Chile (33°30'S, 71°37'W) to hypoxia and OA within predicted levels and in a full factorial design. Organisms were exposed to 4 different treatments (ambient, low oxygen, high CO, and the combination of low oxygen and high CO) and metabolism was measured after 3 and 6 days. We show that the combination of hypoxia and increased pCO reduces the respiration significantly, compared to a single stressor. The evaluation of synergistic pressures, a more realistic scenario than single stressors, is crucial to evaluate the effect of future changes for coastal species and our results provide the first insight on what might happen in the next 100 years. ; This research is a contribution to ASSEMBLE (grant agreement no. 227799; funded by the European Community: Research Infrastructure Action under the FP7 "Capacities" Specific Program), ESTRESX project funded by the Spanish Ministry of Economy and Innovation (ref. CTM2012-32603), LINCGlobal (funded by The Spanish National Research Council (CSIC) and The Pontificia Universidad Católica de Chile (PUC) to facilitate interaction between Latin American and Spanish researchers in the field of global change). AS was funded by a fellowship from the Government of the Balearic Islands (Department on Education, Culture and Universities) and the EU (European Social Fund), LR was funded by a fellowship from the Government of Chile (CONICYT, Becas Chile Program) and IH was funded by a JAE-DOC fellowship from the Spanish Government. NAL acknowledged funds by Fondecyt 1090624 during the experimental phase and the Millennium Nucleus Center for the Study of Multiple-drivers on Marine Socio-Ecological Systems (MUSELS) by MINECON Project NC120086 also supported this work during the final stages. ; Peer Reviewed