Environmental drivers and vulnerability of reef fishes highlight the need for multi-habitat conservation in remote...

Understanding fish-habitat associations is crucial for effective fishery management and biodiversity conservation. The distribution of fish among suitable and available habitats is primarily determined by species' environmental requirements at different life stages and their bio-ecological interactions. Key habitat features, such as benthic cover, substrate type, as well as depth and water temperature, are important predictors of reef fish distribution. This study assessed fish distribution patterns in a remote tropical insular ecosystem (Trindade Island) from the perspective of conservation-related traits, including biomass, endemism, and species vulnerability, in response to environmental drivers. We surveyed reef, rhodolith, macroalgae beds, and sand bottom habitats across shallow to mesophotic depths using baited remote underwater stereo-video systems. Multivariate analyses and modeling revealed that fish assemblages at Trindade Island are structured by benthic habitats and depth (10-79 m), with patterns varying according to island side. Species richness, relative abundance, and endemic richness were influenced by reef cover and island side, whereas species vulnerability and endemic abundance increased with depth. These results highlight the importance of an integrated management approach that considers the insular shelf gradient of benthic habitats to safeguard marine biodiversity and the ecological functions provided by each habitat.