Science of Marine Reserves Meta-analysis

See the meta-analysis results

Download the global meta-analysis publication

Access the Science of Marine Reserves database

meta-analysis methods

The Science of Marine Reserves meta-analysis investigates three primary questions:

1. Are density, biomass, individual size, and/or species richness significantly and consistently affected by full protection inside marine reserves?
2. Do changes in biomass, density, size, and/or richness inside a reserve differ in temperate versus tropical regions?
3. Do the effects of reserves vary by taxonomic group?

This meta-analysis is based on a database of studies that document biological effects of marine reserves compiled via a comprehensive survey of the peer-reviewed scientific literature. We included only peer-reviewed studies of fully-protected, no-take marine reserves and only those studies for which effects were measured for individual reserves.

Studies must have measured at least one of four key biological variables

1. numerical density of organisms per area
2. biomass of organisms per area
3. individual organism size, and/or
4. species richness per area

Studies must have measured the variable(s) either:

1. inside and outside the reserve,
2. before and after reserve implementation, or
3. inside and outside the reserve both before and after implementation.

The resulting database contains 149 peer-reviewed scientific publications published between 1977 and 2006 of 124 different marine reserves located in 29 countries. Because some reserves are studied in more than one publication and some publications study multiple reserves, the database includes 221 “studies.” We classified each reserve as being located in either a temperate (53 reserves) or tropical (71 reserves) ecosystem based on latitude, region, and habitat.

The results show that the abundance, diversity, biomass, and size of fishes, invertebrates, and seaweeds usually increase dramatically inside marine reserves. Species that are fished show the biggest changes, sometimes increasing 10 or 20 times in marine reserves. These outcomes are consistent across different habitats in tropical and temperate waters.

See the Latin American and Caribbean meta-analysis results here.

COMING SOON! European meta-analysis results.

Learn more about the Science of Marine Reserves project.