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Abstract Conflicting results remain on the impacts of climate change on marine organisms, hindering our capacity to predict the future state of marine ecosystems. To account for species-specific responses and for the ambiguous relation of most metrics to fitness, we develop a meta-analytical approach based on the deviation of responses from reference values (absolute change) to complement meta-analyses of directional (relative) changes in responses. Using this approach, we evaluate responses of fish and invertebrates to warming and acidification. We find that climate drivers induce directional changes in calcification, survival, and metabolism, and significant deviations in twice as many biological responses, including physiology, reproduction, behavior, and development. Widespread deviations of responses are detected even under moderate intensity levels of warming and acidification, while directional changes are mostly limited to more severe intensity levels. Because such deviations may result in ecological shifts impacting ecosystem structures and processes, our results suggest that climate change will likely have stronger impacts than those previously predicted based on directional changes alone.

Marine protected areas are proposed to protect elasmobranchs (sharks, skates, and rays) but the fishing impact from small-scale fisheries in these areas is unknown. From 1256 fishing operations carried out in partially protected and unprotected areas in six Mediterranean countries, this study shows that catches were higher in partially protected areas than in unprotected areas, indicating poor small-scale fisheries management as a threat for these species.