Hypoxia surpasses the impacts of ocean acidification and warming in marine biota

Dr Rui Rosa1, Ms Catarina Santos1, Dr Verónica Ferreira2, Dr Hans Pörtner3, Dr Carlos Duarte4, Dr. Lisa Levin5, Mr Eduardo Sampaio1

1MARE – Marine and Environmental Sciences Centre, Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Cascais, Portugal, 2MARE – Marine and Environmental Sciences Centre, Department of Life Sciences, Universidade de Coimbra, , Coimbra, Portugal, 3Alfred-Wegener-Institut, Bremerhaven, Germany, 4King Abdullah University of Science and Technology, Thuwal , Saudi Arabia, 5Scripps Institution of Oceanography, San Diego, USA

Continuous CO2 emissions are warming the Earth’s water masses, and its oceanic uptake is leading to seawater acidification via carbonate chemistry disruption (the well-known process of ocean acidification). Concomitantly, the warming-related accentuation of natural termoclines translates into lower oxygen solubility in the upper oceanic layers. The resulting ocean deoxygenation is exarcebated by increased eutrophication and upwelling frequency of deep anoxic/hypoxic waters in coastal areas, provoking mass marine biota mortality and fisheries collapse worldwide. The aim of the present study was to investigate which of these climate change-related stressors elicit greater impacts in the marine biota, at different levels of biological organization. To estimate such effects, we performed a meta-analysis (~900 separate experiments), divided into four categories: ocean acidification, warming, both these stressors combined, and hypoxia (deoxygenation). Although all stressors showed significant effects, an unequivocally stronger impact was found for hypoxia. This response pattern was consistent across several taxa, and at different life stages, for nearly all biotic variables measured, namely survival, abundance, metabolism, growth, reproduction and larval development. Our findings suggest that, ocean deoxygenation will be a, if not, the main deterrer of life in future oceans. Moreover, as there are theoretical basis predicting synergisms, establishing the interplay of ocean deoxygenation with warming and acidification is key to fully understand climate change impacts on marine life and socio-economical activities.


Rui Rosa graduated in Marine Biology by Faculty of Sciences, University of Lisbon (FCUL), in 1999 and completed a PhD degree in Biology by the same institution in 2005. Subsequently, Rosa carried out his post-doctoral activities on Climate Change research at Univ. Rhode Island (USA), funded by FCT, and US National Science Foundation.

Rosa lab (http://www.ruirosalab.com) seeks to understand how future environmental changes, such as ocean deoxygenation, warming and ocean acidification, affect marine biodiversity. Rosa has authored 170 papers in international peer reviewed journals, some in top-ranked journals such as Nature Geoscience, PNAS, Proc. Royal Soc. London, Global Ecology and Biogeography, Global Change Biology, and Biology Letters, among others, as well as highlighted in renowned media – e.g. BBC News (three times), Discovery Channel, National Geographic (two times), The New York Times, The Times – and in European Commission Alerts. He has been engaged in internationally-renowned evaluation programs, including those of US National Science Foundation, NERC (UK), ANR (FR), National Geographic, and US MIT Sea-Grants.

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