Discovery of a new submarine hydrothermal system off the western Pontine Islands (central-Tyrrhenian Sea)

Different seafloor areas affected by CO2 fluid emissions have been discovered offshore the Western Pontine Islands (central-Tyrrhenian Sea) along the outer insular shelf surrounding Zannone Island in a water depth varying from 120 to 140 m. These sites have been studied, in the framework of two research projects (MaGIC Project and Ritmare Project) integrating ROV video observations, high resolution multibeam bathymetry, high resolution seismic profiles, water, gas and sediment sampling. Different morphological and biological features such as pockmarks, giant pockmarks, lithified sediments, mounds, cones, gas plumes, bubble streams and bacterial mats have been detected. Geophysical, geochemical and geological data analysis has permitted to speculate the possible genesis, evolution through the time and gas source of such peculiar features, while biological study are being carried out with the aim to verify the influence of fluid emissions on benthic communities. The occurrence of giant and complex fluid emission depressions in shallow water (less than 140 m) represents a relevant finding due the scarcity of such features in the Tyrrhenian area and updates the current knowledge regarding the spatial distribution of the CO2 vents along the Tyrrhenian Sea margins. Furthermore, because the accessible depth this site could be considered optimal for the installation of a multi-disciplinary permanent seafloor observatory to study\monitor the effects of CO2 enriched fluids on benthic communities.