Ecosystems. In: Climate and Environmental Change in the Mediterranean Basin – Current Situation and Risks for the Future. First Mediterranean Assessment Report

Despite covering only 0.82% of the ocean’s surface, the Mediterranean Sea supports up to 18% of all known marine species, with 21% being listed as vulnerable and 11% as endangered. The acceler- ated spread of tropical non-indigenous species is leading to the “tropicalization” of Mediterranean fauna and flora as a result of warming and extreme heat waves since the 1990s. The acidification rate in the Mediterranean waters has ranged between 0.055 and 0.156 pH units since the pre-industrial period, affecting the marine trophic chain, from its primary producers (i.e., coccolithophores and fo- raminifera) to corals and coralline red algae. Projections for high emission scenarios show that endemic assemblages will be modified with numerous species becoming extinct in the mid 21st century and changes to the natural habitats of commercially valuable species, which would have many repercussions on marine ecosystem services such as tourism, fisheries, climate regulation, and ultimately on human health. Adaptation strategies to reduce environmental change impacts need effective mitigation policies and actions. They require anticipatory planning to enable them to tackle problems while they are still manageable. Given the diversity of each Mediterranean sub-basin, wider monitoring coverage is needed to strengthen our knowledge about the different adaptation processes that characterize and best suit each geographical zone. Adaptation implies the implementation of more sustainable fishing practices as well as reducing pollution from agricultural activity, sustainable tourism or developing more effective waste management. Marine protected areas can potentially have an insurance role if they are established in locations not particularly vulnerable to ocean acidification and climate change.