Evaluating spatiotemporal patterns and process that influence the functional organization and variation of biological assemblages is an important step for ecosystem management. Functional diversity (FD) quantifies these patterns among species by considering the relative magnitude of differences among species based on the value and range of their functional, morphological and behavioral traits. This metric allows us to identify the niche space for each species by considering both trait redundancy and relative species abundance. This study evaluated changes in fish FD inside the Marine Protected Area (MPA) Buck Island Reef National Monument in the U.S. Virgin Islands between 2001 and 2010. A literature review was conducted to extract 25 functional traits related to the trophic function of 166 fish species that inhabit this MPA. Traits and abundance of species were used to calculate indexes of functional richness and variation. A non-parametric permutational multivariate analysis of variance (PERMANOVA) was used to test for spatial and temporal variations in FD indexes by considering effects of habitat type, year of survey, and the interaction between these factors.
Significant differences for all indexes were found among time and space, and interaction between factors was only found for functional variation (p-value < 0,05), suggesting that changes in fish trait composition is habitat and time dependent among studied fish communities. Our analysis suggests that important changes in functional trait composition occurred in fish assemblages of this MPA in the last decade. Our results show that protection efforts on coral reef areas that support high levels of functional richness and variation are important strategies to manage for ecosystem resilience. This study contributes to the understanding of ecosystem changes in MPAs and impacts on the fish FD, by providing useful methods for application in similar assessments elsewhere in the Caribbean and worldwide.