A team of scientists, led by Enric Sala, a marine ecologist with the Centre for Advanced Studies of Blanes in Spain, investigated rocky reefs around Mediterranean shores and the impact of protection level on the health of these marine ecosystems.
In total, 32 sites were surveyed from both marine protected areas and unprotected areas across the Mediterranean. The results showed “remarkable variation in the structure of rocky reef ecosystems” with three distinct groups: (1) high fish and algal abundance, (2) lower fish abundance but high algal abundance, and (3) lower fish abundance and extensive barrens.
In conclusion the team describe protection level and primary production as the only variables significantly correlated with community biomass. “Fish biomass was significantly larger in well-enforced no-take marine reserves, but there were no significant differences between multi-use marine protected areas (which allow some fishing) and open access areas at the regional scale”.
A major insight from the study is that, at least in the Mediterranean, partially protected marine protected areas are not effective in restoring fish populations.