Michela Ingrassia

Black coral (Anthozoa, Antipatharia) forest near the western Pontine Islands (Tyrrhenian Sea)

Dense aggregations of antipatharian corals have been discovered by means of remotely operated vehicle (ROV) photo-imaging off the western Pontine Islands (Central-Tyrrhenian Sea, Italy). These black coral assemblages are mainly composed of Parantipathes larix and Leiopathes glaberrima . This discovery constitutes an update of their habitat distribution for the Mediterranean Sea and is relevant for the development of focused protection measures for the study area.

Evidence of a shallow water submarine hydrothermal field off Zannone Island from morphological and geochemical characterization: implications for Tyrrhenian Sea Quaternary volcanism

Discoveries from multibeam bathymetry and geochemical surveys performed off Zannone Island (western Pontine Archipelago, Tyrrhenian Sea) provide evidence of an undocumented hydrothermal field characterized by ongoing fluid emissions and morphologically complex giant depressions located in shallow water ( 250 m) that host pockmarks, mounds, small cones and active fluid vents, and which are interpreted as complex fluid escape features developed both through vigorous-explosive events and steady seepage. Their spatial distribution suggests that the NE-SW trending faults bounding the Ponza-Zannone structural high and the shallow fractured basement are favorable conditions for the upward migration of hydrothermal fluids. Moreover, we performed a detailed geochemical study to investigate the source of the hydrothermal fluids. The geochemical signature of the collected fluids provides information of active CO2-dominated degassing with a significant contribution of mantle volatiles, with measured 3He/4He values > 3.0 Ra that are similar to those recorded at Stromboli and Panarea volcanoes. The hydrothermal system produces volatiles that may originate from residual magma batches, similar to the Pleistocene trachytes cropping out in the SE sector of Ponza Island, that were probably intruded in the shallow crustal levels and never erupted. The discovery of the Zannone hydrothermal field updates the record of active hydrothermal areas of the Mediterranean Sea. Moreover, the recognition of several giant hydrothermal depressions characterized by a complex morphology is peculiar for the Mediterranean Sea.

High potential for temperate viruses to drive carbon cycling in chemoautotrophy‐dominated shallow‐water hydrothermal vents

Viruses are the most abundant life forms in the worlds oceans and they are key drivers of biogeochemical cycles, but their impact on the microbial assemblages inhabiting hydrothermal vent ecosystems is still largely unknown. Here, we analysed the viral life strategies and virus-host interactions in the sediments of a newly discovered shallow-water hydrothermal field of the Mediterranean Sea. Our study reveals that temperate viruses, once experimentally induced to replicate, can cause large mortality of vent microbes, significantly reducing the chemoautotrophic carbon production, while enhancing the metabolism of microbial heterotrophs and the re-cycling of the organic matter. These results provide new insights on the factors controlling primary and secondary production processes in hydrothermal vents, suggesting that the inducible provirus-host interactions occurring in these systems can profoundly influence the functioning of the microbial food web and the efficiency in the energy transfer to the higher trophic levels.

New Insights on Failure and Post-failure Dynamics of Submarine Landslides on the Intra-slope Palmarola Ridge (Central Tyrrhenian Sea)

Newly collected multibeam and seismic data on the intra-slope Palmarola ridge show widespread pockmarks and landslide-related morphologies along its flanks. In detail, two main types of slope failures were identified: disintegrative-like and cohesive like landslides. The first type is characterized by a complex of small, nested scars affecting the steep and tectonically-controlled eastern flank of the ridge, suggesting a genesis related to retrogressive processes. The cohesive landslides affect the northern flank of the ridge and are characterized by larger scars, where material was not completely evacuated, and well-defined debris deposits at their base, with the development of pressure ridges. Tectonic activity and slope gradients represent the main controlling factors for the development of instabilities; moreover, we noted a relationship between pockmarks and landslide scars.

Spiculosiphon oceana (Foraminifera) a new bio-indicator of acidic environments related to fluid emissions of the Zannone Hydrothermal Field (central Tyrrhenian Sea)

The new record of a shallow-water submarine hydrothermal field (<150 m w.d.) in the western Mediterranean Sea (Tyrrhenian Sea, Italy) allows us to study CO2 fluid impact on benthic foraminifers. Benthic foraminifers calcification process is sensitive to ocean acidification and to local chemical and physical parameters of seawater and pore water. Thus, foraminifers can record specific environmental conditions related to hydrothermal fluids, but at present their response to such activity is poorly defined. The major outcome of this study is the finding of a very uncommon taxon for the Mediterranean Sea, i.e., the Spiculosiphon oceana, a giant foraminifer agglutinating spicules of sponges. This evidence, along with the strong decrease of calcareous tests in the foraminiferal assemblages associated to hydrothermal activity, provides new insights on the meiofauna living in natural stressed environment. In particular, observations obtained from this study allow us to consider S. oceana a potential tolerant species of high CO2 concentrations (about 2-4 times higher than the normal marine values) and a proxy of acidic environments as well as of recent ocean acidification processes.