Fish community structure and diversity partitioning in the nearshore benthoscapes of San Salvador, Bahamas

Abstract

Exploring variation in community structure and species diversity across spatial scales provides insights into factors structuring communities and promoting diversity and informs management and conservation. This study focused on spatial variation in fish community structure and diversity in the nearshore benthoscapes of San Salvador, Bahamas. Data were collected at thirteen sites across five regions and three different habitat types (patch reefs, high relief, and rubble sites) using video and roving snorkeler observations, which were analyzed separately. Although there were similar sets of dominant species around the island, multivariate analyses indicated significant differences in community structure among regions and sites and at the within-site scale, which can be attributed to differences among habitat types and localized environmental effects at the site level. A total of 55 species were found in the video data; 141 species were found in the snorkeler observations, likely due to the presence of a greater variety of habitats (deeper patch reefs, seagrass beds and mangroves), larger area observed, and increased likelihood to observe cryptic species. Diversity partitioning indicated that β₂ (among sites within a region) and β₃ (among different regions) diversity contributed greater than expected numbers of species to overall γ-diversity. The different regions around the island and the mix of habitats within each region may provide some measure of resilience in fish communities to disturbances and changing environmental conditions. Our results underscore the importance of protecting mixes of habitat in conservation and management efforts focused on the nearshore benthoscapes of tropical islands such as San Salvador.