Functional diversity of fish assemblages across a latitudinal gradient in coral ecosystems of the Mexican Tropical Pacific

Abstract

Fishes are relevant indicators of reefs’ conservation status due to the wide variety of functions they perform in the ecosystem. Natural and anthropogenic-induced threats are causing declines in biomass and diversity locally, with immediate effects on trophic structure and ecosystem function. This study evaluated the spatial variation of species richness and the alpha and beta functional diversity of fish assemblages across the Mexican Tropical Pacific (MTP). Visual fish censuses were performed in nine localities between 2012 and 2020. The results showed that species richness and functional diversity of the reef-associated fish assemblage vary at different spatial scales (local and regional), with the highest variability on the local scale. The functional richness and functional divergence presented high values in most localities. On their part, functional beta diversity among regions was low, with almost no functional turnover, while higher trait turnover was observed among localities. This study complements taxonomic diversity metrics by identifying differences due to local conditions, with human intervention as a critical factor. Therefore, it provides information tools that can help improve the management of marine communities subjected to distinct types and degrees of intervention in the MTP.