Identifying priority habitats in the upper São Vicente Submarine Canyon (Portugal)

Iga-Maria Nestorowicz

Identifying vulnerable marine habitats is fundamental to promote evidence-based management and a sustainable use of our oceans. Although progress in the mapping of marine benthic habitats has been made, geomorphologically and hydrodynamically complex ecosystems such as submarine canyons remain largely unexplored, hampering evidence-based management from taking place in these ubiquitous features worldwide. To address this issue, data from a Remotely Operated Vehicle (ROV) survey in the upper São Vicente Canyon in 2011, was used to carry out a comprehensive assessment of megabenthic habitats occurring between 90 and 560 m, particularly targeting those of conservation concern. Underwater videos from three transects, covering a total of 8.8 kilometres, were analysed through multivariate and visual assessments, and the identified habitats were assessed against a set of criteria derived from current definitions of priority habitats. Ten distinct priority habitats were characterized; six coral gardens, one deep-sea sponge aggregation, two circalittoral sponge aggregations, and one habitat of a strictly protected sea urchin. Substrate type and depth turned out to be particularly important for the distribution of habitats. The gathered knowledge should aid in the implementation of sensible protection measures of the canyon area, and will moreover be required for future mapping efforts in submarine canyons.