Environmental, fishing and benthic linkage in the mud volcano field of the Spanish margin of the Gulf of Cádiz

The Gulf of Cadiz is located in the boundary of two lithospheric plates, this tectonic activity promote fluid rich hydrocarbon emissions from subsurface reservoirs and the formation of several mud volcanoes. The seabed and sedimentological heterogeneity, the complex oceanographic circulation, and the low fishing activity in certain areas may promote high biodiversity and complex habitats (habitat 1170 and 1180, Natura 2000). Environmental variables (fishing activity, substrate types, near bottom currents) and fauna collected with beam-trawl have been compared for several mud volcanoes and adjacent bottoms in order to understand the spatial distribution of both habitats and environmental/anthropogenic variables. The faunistic samples yielded high abundances, biomass and species richness in Gazul, Pipoca and Chica but low ones in Anastasya. In relation to environmental variables and fisheries activity, there is a strong correlation with the substrate type, depth, salinity and near-bottom current as primary variables influencing the distribution of habitats of different mud volcanoes. In this context, high species richness, abundance and biomass was found in areas with authigenic carbonates, coarse sediments, high near-bottom current speed, low salinities and low fishing activity.Versión del edito