Rapport de Campagne. VIDEOCOR1-02. Septembre 2017

This Videocor1-02 expedition (September 2017) was done in order to complete the VIDEOCOR1 expedition that took place in May 2017. The objectives were to deploy the Ariane HROV to complete the video and photo coverage of white corals (Madrepora oculata) in the Cassidaigne canyon and to explore areas predicted by a habitat suitability model. No samples were collected. In total, we were granted three additional dives and all three were executed due to excellent weather conditions. The H-ROV Ariane had no technical problems. No samples were collected. The three dives allowed to complete the video coverage of two sites: Cassis-200 and Wassis-Wall. · Cassis-200: the coverage of the southern part could be completed without any problems because there was no water current. Many small colonies of red corals (Corallium rubrum) were observed amongst white corals (Madrepora oculata). · Cassis-Wall is a site at the mouth of the canyon. We explored a large area of the zone predicted by the habitat model without finding any white corals except for three colonies. On the other hand we discovered large stretches covered by gorgonians Viminella flagellum and Callogorgia verticillata, of which we will be able to measure the population parameters. At the end of the third dive, Ariane's optical fibre had probably been caught up in abandoned fishing gear or on the rocks on the seafloor resulting in a loss of communication. However the functionality allowing us to disconnect the optical fibre and to recover the ROV in a very professional manner without wasting time.