Habitat distribution and associated biota in different geomorphic features within a fluid venting area of the Gulf of Cádiz (Southwestern Iberian Peninsula, Northeast Atlantic Ocean)

Abstract The Gulf of Cadiz (GoC) is influenced by the collision of the Alboran Domain with the North African and South Iberian margins, resulting in a hydrocarbon-rich fluid venting area. The interaction of the Eastern North Atlantic Central Water mass and the Mediterranean Outflow Water strongly influences seabed topography and substrate types. Both geological and oceanographic processes determine the distribution of a wide variety of geomorphic features, habitats, and species. Based on high-resolution multibeam echosounder data (both bathymetric and backscatter) and ground truthing with more than 100 videos and 50 samples, we have mapped and characterized an area of more than 1000 km2 in the shallow part of the Site of Community Importance denominated “Volcanes de fango del golfo de Cadiz” (Mud volcanoes (MVs) of the GoC). The study area shows four main geomorphic features (diapiric structures, MVs, channels, and other erosive related features and flat areas) with seven different substrate types that harbor 11 main habitat types. Some are included in the Habitat Directive (92/43/EEC), such as reefs (Habitat 1170) and submarine structures made by leaking gases (Habitat 1180).