Trophic group responses to marine reserve protection in temperate and tropical reefs: a systematic review and meta-analysis

Marine reserves impact not only exploited species but also other groups, highlighting broader ecological effects within marine communities. While some of these effects are well documented, comprehensive assessments of overall reserve impacts on functional guilds and community structure remain limited. Our systematic review and meta-analyses used structural metrics to test global patterns across 138 tropical and temperate reef reserves, covering seven fish and invertebrate trophic groups and 11 macroalgae and coral morphological groups (99 studies, 679 response-ratio values). In tropical reserves, herbivorous fish presented the highest positive response, followed by carnivores. Potential indirect negative effects may result from predatory fish reducing herbivorous invertebrates and herbivorous fish decreasing macroalgae. Coral cover was higher inside reserves, while algal cover declined. In temperate reserves, herbivorous invertebrate declines did not appear to consistently affect macroalgae, indicating context-dependent outcomes. These results suggest both direct and indirect effects of protection, contributing to valuable insights for ecosystem-based management.