Functional diversity of reef fish assemblages in the Galapagos Archipelago

The Galapagos Archipelagos unique reef biodiversity and distribution patterns are relatively wel l understood compared to the study of local functional diversity processes. We investigated functional diversity patterns in coastal reef fish communities using stereo Baited Remote Underwater Videos systems (stereo-BRUVs). We collected relative abundance data based on 41,594 individual fish belonging to 121 reef fish species and assessed functional diversity using seven functional traits and a combination of functional alpha-diversity and beta-diversity indices. We found differences between bioregions; however, we observed no differences in reef fish assemblages between the geographic strata (distinct habitat types) within regions. Low functional alpha-diversity within assemblages but high environmental variability at sma l l spatial scales has resulted in a consistent mod-erate functional beta-diversity between assemblages and high functional diversity at an archipelago-wide scale. While there is a low diversity of functional roles, the most abundant species represent a few distinct and sup-portive functional roles in Galapagos reef ecosystems. Such functional roles likely have redundancy; however, many other functional roles are likely under-represented and vulnerable. The variable functional diversit y be-tween Galapagos bioregions facilitates an ecological interpretation that supplements traditional species diversit y indices. Therefore, we suggest a combination of species compositions and functional diversity metrics be used in the future management of Galapagos marine communities.