Benefits and risks of incremental protected area planning in the Southern Ocean

Establishing representative Marine Protected Area (MPA) networks in Areas Beyond National Jurisdiction (ABNJ) is a priority for the conservation of marine biodiversity and the sustainability of socio-ecological systems under increasing pressure from global environmental change. Here we use a systematic conservation planning framework and four planning scenarios to test the suitability of a bioregional planning approach to deliver a representative network of MPAs for the Southern Ocean. We find that if existing and proposed MPA designs are not adapted, some conservation features will remain underrepresented and very large MPAs in yet to be planned-for domains will be required. Our analysis demonstrates that while existing and proposed Southern Ocean MPAs protect significant conservation features, achieving representative protection under the bioregional approach is contingent on political will to adapt existing protected areas at ongoing stages of the incremental planning process. These findings have implications for conservation planning beyond the Southern Oceans and particular relevance for achieving representative marine protection in ABNJ.