Marine ecosystems will be increasingly affected by the effects of ocean acidification and ocean warming, which can be exacerbated by further stressors such as hypoxia. Environmental change can either influence the physiology of plankton, marine fish and invertebrates directly across all life stages or affect them indirectly by changing the composition and quality of food web connections. This will alter the species abundance and composition of future ecosystems, entailing putative changes in ecosystem services for humans by e.g. affecting artisanal and industrial fisheries and the oceans’ value for recreation and tourism.
Many effects of ocean acidification and warming on organismal physiology can only be traced back from the organismal to cellular and molecular levels. Projecting species robustness and ecosystem resilience requires integration of these levels. Projecting future species composition at ecosystem level requires the integration and extrapolation of variable species responses. These responses are currently identified only for a number of selected taxa, and knowledge is especially needed for those species projected to be invasive and undergo changing interactions.
This can be accomplished by meta-analyses and models that consider climate scenarios, multiple stressors and species interactions over time. Both have been included in the recent IPCC AR5 WGII report, based on emerging data of synergistic effects of ocean acidification and warming mainly for fish and marine invertebrates, including also estimates of economic impacts. A range of marine ecosystem services to human societies might be impacted by ocean acidification and warming. First results from BIOACID II show concern among affected stakeholders - ranging from fishers to tourism operators - is growing.
For fish stocks, which comprise the most important food provision service of the oceans, available data are still too patchy to support a high level of confidence in projection of ocean acidification and warming impacts and, so far, the effect of ocean warming alone has been modelled to project changes in catch potential. There is an urgent need to increase the level of knowledge and data available for modelling at the ecosystem level, including food webs and higher trophic levels such as fish to reliably project the synergistic effects of ocean acidification and ocean warming on marine ecosystems and their services to inform economists, political decision makers and society.
More about the science of Theme 3.