Fig. 1: Key organisms in the Southern Ocean and twenty-first-century ocean acidification in Marine Protected Areas.

Map of established (South Orkney Islands Southern Shelf and Ross Sea region) and proposed (Weddell Sea, East Antarctic, Western Antarctic Peninsula) Marine Protected Areas (MPAs). Key species and groups that may be negatively impacted by ocean acidification (see references in the main text) are depicted around the map (not to scale). Bar plots denote the top 200 m average (left) and bottom (right) pH in the five different MPAs in the 1990s (dark gray) and in the 2090s (colors) for the four emission scenarios (sorted from low emission to high emission). For the Weddell Sea, East Antarctic, Ross Sea and Antarctic Peninsula MPAs, the hatched bars denote the average pH for the continental shelf south of the 2000 m isobath (gray contour on the map). Note the arrows for the SSP5-8.5 scenario, indicating a lower pH on the continental shelves than for the whole-MPA average.