Evaluating whether MPA management measures meet ecological principles for effective biodiversity protection

The use of Atlantic seascapes for marine protected areas planning in the context of the marine biological diversity of areas beyond National Jurisdiction agreement

International biodiversity agreements aim to expand protected areas by up to 30 %, including areas beyond national jurisdiction. The high seas' extent, shared governance, and limited biodiversity data challenge the identification of large-scale areas to be protected. This study uses seascapes defined from satellite data as proxies for biodiversity in the Atlantic high seas to assist in preliminary designations of protected areas. Seascape's extent is compared with modelled distributions of phytoplankton groups, fish species, and endangered species to assess their biodiversity representativity. Furthermore, the study addresses trade-offs between protecting 30 % of each seascape, covering endangered species distribution, and main human activities in high seas (shipping and fishing). Marine traffic lanes are defined where there is currently more activity, redirecting other activities in the centroid of the seascapes to these lanes. This strategy protects 21 %, 35 %, 44 %, and 48 % of the habitat of the considered endangered species, while displaced human activity ranges from 3 % to 7 % for shipping and up to 4 % for fishing. The size of areas with high concentrated noise increases by 7.8 %, affecting all trophic levels, but areas without activities with only propagated noise increase by around 78.9 %. These results suggest that protecting at least 30 % of each seascape with activity lanes is a good prioritization starting point for high seas protection, which can be redefined later based on the presence of rare species or key habitats and socio-economic factors agreed with stakeholders within a systematic spatial planning approach.