From chemosynthesis-based communities to cold-water corals: Vulnerable deep-sea habitats of the Gulf of Cádiz

The Gulf of Cádiz (GoC) represents an area of ecological importance within the northeastern Atlantic Ocean due to the presence of Mediterranean and Atlantic water masses, a heterogeneous seafloor and a biological confluence. Nevertheless, information on the presence of vulnerable deep-sea habitats is still very scarce and it is of importance for further habitat monitoring within the context of the Habitats and Marine Strategy Framework Directives and for improving conservation and resource extraction management. From 2010 to 2012, fluid migration and emission related edifices (e.g., mud volcanoes, diapirs) from the Spanish continental margin of the GoC have been explored using a remotely operated vehicle (ROV; Liropus 2000) and an underwater camera sled (UCS; APHIA 2012) as well as several devices for collecting sediment and fauna. Different vulnerable deep-sea habitats have been observed, including anoxic bottoms with bacterial mats, sea-pen communities, sponge aggregations, antipatharian and gorgonian communities and also cold-water coral banks. Some of these habitats are included in conservation lists of the habitat directive and in international conventions (OSPAR, RAC/SPA), however some of them are located in areas of the GoC that are exposed to intense trawling. The diversity of habitats detected in the Spanish continental margin of the GoC highlights the importance of seepage related edifices as inducers of seabed and habitat heterogeneity in deep-sea areas.