Near-pristine benthic habitats on the Francesc Pagès Bank, Alboran Sea, western Mediterranean

This study provides a first characterization of the geomorphic features and relative habitats of the Francesc Pages Bank, located on the upper slope of the Moroccan continental margin in the southern Alboran Sea, western Mediterranean. The Francesc Pages Bank is an ellipsoidal structural high covering 80 km2 within a depth range of 76–580 m. High-resolution swath mapping allowed to recognize different geomorphic features on the top of the Bank, including crests, banks and ridges. An automatic classification of multibeam sonar data has been performed to identify and map the different physical habitats using terrain parameters derived from the bathymetry as surrogate descriptors. A remotely operated vehicle (ROV) video track acquired in the area showed the occurrence of several dense and uncommonly well-preserved megabenthic assemblages composed of gorgonians, soft corals, and several demosponge species. Multivariate statistical analyses performed on species abundance and terrain parameters derived from ROV observations allowed to define the main substrates governing the distribution of the observed benthic species, which coincide with some of the physical habitats detected by the multibeam automated classification.