Characterizing the deep insular shelf coral reef habitat of the Hind Bank marine conservation district (US Virgin Islands) using the Seabed autonomous underwater vehicle

The benthic communities of the deep insular shelf at the Hind Bank marine conservation district (MCD), an important spawning aggregation site for groupers, were studied with the Seabed autonomous underwater vehicle (AUV) at depths between 32 and 54 m. Four digital phototransects provided data on benthic species composition and abundance of the insular shelf off St. Thomas, US Virgin Islands. Within the western side of the MCD, well-developed coral reefs with 43% mean living coral cover were found. The Montastrea annularis complex was dominant at all four sites between 33 and 47 m, the depth range where reefs were present. Maximum coral cover found was 70% at depths of 38–40 m. Quantitative determinations of sessile benthic populations, as well as the presence of motile megabenthic invertebrates and algae were obtained. The Seabed AUV provided new quantitative and descriptive information of a unique coral reef habitat found within this deeper insular shelf area.