The global number of marine protected areas grew exponentially in the last decade to meet international targets. Most of them are partially protected areas (PPAs). Yet, their ecological effectiveness remains unclear due to the high variability of allowed uses. Here, we performed the first global meta-analysis of PPAs following a new regulation-based classification system, to assess their ecological effectiveness. Overall, PPAs are effective relative to unprotected areas but allowed uses are the key feature determining their performance. Highly and moderately regulated PPAs provide higher biomass and abundance of commercial fish species, while weakly regulated PPAs do not exhibit differences relative to unprotected areas. Importantly, the effectiveness of some PPAs can be enhanced by the presence of an adjacent fully protected area (no-take zone). We conclude that limited and well-regulated uses in PPAs and the presence of an adjacent fully protected area confer ecological benefits, on which socio-economic advantages are derived.
Lack of evidence that governance structures provide real ecological benefits in marine protected areas
