Marine partially protected areas: drivers of ecological effectiveness

The number of marine protected areas (MPAs) has grown exponentially worldwide over the past decade in order to meet international targets. Most of these protected areas allow extraction of resources and are therefore designated as "partially protected areas" (PPAs). However, the effectiveness of PPAs remains unclear due to the high variability of use types permitted. Here, we carried out what we believe to be the first global meta-analysis of PPAs using a regulation-based classification system for MPAs to assess their ecological effectiveness. This novel classification allows for unambiguous differentiation between areas according to allowed use, which is the key feature determining PPA performance. Highly and moderately regulated areas exhibited higher biomass and abundance of commercial fish species, whereas fish abundance and biomass in weakly regulated areas differed little from unprotected areas. Notably, the effectiveness of moderately regulated areas can be enhanced by the presence of an adjacent fully protected area. We concluded that limited and well-regulated uses in PPAs and the presence of an adjacent fully protected area confer ecological benefits, from which socioeconomic advantages are derived.