PRESERVATION POTENTIAL AND DIVERSITY OF TROPICAL ROCKY SHORE GASTROPOD COMMUNITIES, SAN SALVADOR ISLAND, BAHAMAS

Abstract

This study explores spatial distribution, species diversity, and preservation potential of modern rocky intertidal gastropod communities from San Salvador Island, Bahamas. Using a hierarchical sampling approach, 17,703 intertidal gastropod specimens representing 9 genera and 15 species were recorded from 480 quadrats along 120 transects at 40 sites sampled at ten localities around the island. All localities are dominated by several species of littorinids and neritids. The rank-abundance structure was comparable across all localities, with the same species dominating at all but one locality. The hierarchical sampling scheme revealed a gradual increase in diversity across sampling levels, with most notable increase observed between site-level and locality-level diversity estimates. Habitat diversity estimates did not vary from bare and exposed surfaces to sheltered pits, crevices, and tide pools. Across energy regimes, there was no meaningful shift in habitat occurrences to more sheltered, protected habitats. Species occurrences in sheltered habitats should augment fossilization potential of those assemblages because, as shown in some paleontological studies, there is evidence of rocky intertidal environments from such settings as tide pools, pits, and crevices. Indeed, when data are restricted to more preservable, sheltered settings only, a good representation of total biodiversity and overall community structure of sampled faunal associations is still retained. Moreover, because the sampled communities appear remarkably homogeneous across and within localities, even a highly fragmentary fossil record (e.g., small area in one locality) would likely collect a substantial fraction of biodiversity and community structure of rocky intertidal communities of San Salvador Island.