Central and South Atlantic Region

The Central and South Atlantic Oceans can be best characterized as a collection of sub-regions with distinctly different terrestrial influences and oceanographic circulation, as well as different fisheries harvests and human communities that depend on them. Ocean warming and acidification affect the entire region. Coastal waters also experience impacts from nearby landmasses and human communities, such as pollution from agricultural fertilizer, nitrogen and sulfur emissions from fossil fuel combustion and agriculture, and decreasing salinity from Antarctic ice melting. All of these impacts can add to acidification directly or contribute to eutrophication and subsequent deoxygenation, which may worsen the response of marine organisms to acidification. In the four FAO fishing areas that make up this region, 32%-57% of the fish stocks have no room for further expansion by commercial fishing. Overall catch trends across the region have been level or declining in the past two to three decades. Of the taxonomic groups most likely to be directly affected by ocean acidification, finfish, mollusks, crustaceans, and corals provide the most benefits to fisheries in the Central and South Atlantic regions. Given the negative response of bivalve mollusks to ocean acidification in laboratory studies, it seems that artisanal (e.g. yellow clam M. mactroides, Uruguay), small scale/semi-industrial (e.g., queen conch Strombus gigas, Caribbean) and bivalve aquaculture fisheries (e.g. Eastern oyster C. virginica, Brazil) are regional fisheries that are more likely to be impacted by OA. Changes or loss in physical habitat structure as a result of OA could also negatively affect individual species, such as those living among rhodolith beds (i.e., coralline red algae) in the eastern Caribbean and off the coast off Brazil. So far there is no evidence that major open ocean finfish fisheries in this area (e.g. hake, tuna, billfish, sardines, anchovy) will be directly impacted by OA, but current thinking suggests that ocean acidification will most likely affect finfish fisheries through changes in trophic relationships, such as those related to a decrease in overall food availability and/or the flow of energy among trophic levels. The Central and South Atlantic region is bordered by many nations whose per capita GDP ranks in about the lower two-thirds of the world’s nations. Many nations bounding this region also have less resilient human communities for withstanding possible losses of natural resources. Given the strong probability that OA will act hardest on near-shore and smaller scale fisheries in this region, it has the potential to worsen food distribution inequality that already exists and remove an important source of revenue to coastal communities in Central and South Atlantic. If ocean acidification and temperature rise result in range shifts of vulnerable yet economically important species, small-scale fishers will require local management strategies that are flexible enough to allow them to target a changing variety of accessible species using different gear types. Helping subsidize changing gear, retraining local fishers for other occupations, or helping identify and cultivate nutritional alternatives will likely be necessary for many local jurisdictions in the Central and Southern Atlantic, given the relatively low regional income and social resilience in many bordering nations. Large-scale fishers, on the other hand, may need policies that are geographically flexible that allow them to go farther afield for the same species. The dissimilarity of these two fishery categories and their responses points to the need for policy and adaptation research that address different scales. Nevertheless, close coordination among local, regional, and national authorities as well as user groups and researchers has been demonstrated to yield quick, effective responses to ocean acidification events elsewhere. Involving end users in decision-making and governance will lead to more effective outcomes. Sarah Cooley1, Anthony Charles1, Andreas Andersson, Alexander Arkhipkin, Vicky Lam, Juan Carlos Seijo and Jean-Pierre Gattuso2.