Habitat determines predation effects on sessile marine invertebrate communities at a tropical and temperate site

Species interactions, such as predation, shape biological diversity by influencing community composition, species richness, and abundance. While predation is generally considered stronger in tropical than in temperate ecosystems, evidence from marine systems remains mixed. Many studies report stronger predation at lower latitudes, yet others show substantial predation at higher latitudes, likely due to variation in predator guilds. Studies reporting weaker predation in temperate marine invertebrate communities often focus on suspended substrates accessible to swimming predators like fish, whereas benthic habitats at higher latitudes reveal significant predation effects driven by invertebrate predators. To help reconcile these apparent inconsistencies, we conducted simultaneous experiments in Panama (tropical) and Chile (temperate) to assess the effects of benthic and swimming predators on sessile marine communities at well-studied sites. We used three-month predator exclusion experiments to test predation effects on community assembly, and two-week reciprocal transplant experiments to evaluate predation impacts on established communities. Our results show that benthic predation reduced biomass and altered species composition in both locations, whereas predation effects on suspended communities occurred only in Panama. Although our study focused on one tropical and one temperate location, it highlights the need to consider habitat and predator identity when comparing biogeographical patterns. While predation was generally stronger in Panama, our findings also demonstrate that benthic predators play a key role in structuring temperate marine invertebrate communities in Chile. These findings help reconcile conflicting results in the literature and underscore the importance of considering multiple predator guilds when examining latitudinal patterns of species interactions. • Benthic predators significantly shape sessile invertebrate communities in both Panama and Chile. • Predation effects vary between tropical (Panama) and temperate (Chile) sites. • Reciprocal transplant experiments reveal habitat-specific predation patterns. • Swimming predators affect suspended communities more in the tropics. • Findings underscore the importance of predator guilds in structuring communities.