Exceptional discovery of a shallow-water hydrothermal site in the SW area of Basiluzzo islet (Aeolian archipelago, South Tyrrhenian Sea): An environment to preserve

Abstract

The geological, biological and geochemical features of a particular field of hydrothermal vents, discovered in the Panarea Volcanic Complex during a research survey carried out in 2015, are described for the first time. The site, located at 70–80 m depth off the South-western coast of the islet of Basiluzzo, was named Smoking Land for the presence of a large number of wide and high active chimneys and was characterized in terms of dissolved benthic fluxes, associated macrofauna and megafauna communities and preliminary mineralogy and geochemistry of chimney structures. On the whole field, a total of 39 chimneys, different in size and shape, were closely observed and described; 14 of them showed emission of low temperature hydrothermal fluids of marine origin characterized by acidified chemical conditions. The CTD and benthic chamber measurements highlighted that the Smoking Land is able to form a sea water bottom layer characterized by variable acidity and high DIC and trace elements concentrations; these characteristics weaken moving away from the chimney mouths. The SEM-EDS analysis of the collected solid samples revealed a chimney structure principally composed by amorphous and low crystalline Fe-oxyhydroxides of hydrothermal origins. The ROV explorations revealed a wide coverage of red algae ( Peyssonnelia spp.) colonized by the green algae Flabiella petiolata and by suspension feeders, mainly sponges, but also bryozoans, and tubicolous polychaetes. Although novent-exclusive species were identified, the benthic communities found in association to the chimneys included more taxa than those observed in the surrounding no-vent rocky areas. These first findings evidence a submarine dynamic habitat where geological, chemical and biological processes are intimately connected, making the Smoking Land an important site in terms of marine heritage that should be safeguarded and protected.

Hazard Scenarios Related to Submarine Volcanic-Hydrothermal Activity and Advanced Monitoring Strategies: A Study Case from the Panarea Volcanic Group (Aeolian Islands, Italy)

“…The most recent information and events highlight how Panarea volcanism is still active and potentially dangerous. The presence of magmatic bodies beneath the Panarea area is supported by the geochemical informa-tion coming from the bubbling gases showing δ 13 C CO2 values and 3 He/ 4 He ratios in the same range of those recorded at the active volcano of Stromboli. As a matter of fact, it cannot be excluded that there is a possibility that a volcanic eruption might take place in the future in agreement with Lucchi et al [33] who pointed out that the occurrence of an explosive eruption similar to that which produced the Drauto Formation cannot be ruled out.…”

“…Hydrothermal fluids come out from the main tectonic directrices crossing the Aeolian arc following NE-SW and NW-SE trending alignments [17,36]. Chimneys and other areas of venting fluids have recently been discovered between the island of Panarea and the islet of Basiluzzo, along a possible caldera border [13]. The tectonics drive the distribution of the hydrothermal vents, deposits, crusts, and mineralizations characterizing the whole Panarea offshore [37].…”

“…In November 3, 2002, an explosion occurred 2.5 nautical miles off Panarea island, inducing an intense and long-lasting gas eruption over a shallow depth (2 to 30 m deep) and 2.3 km 2 wide area surrounded by the islets of Panarelli, Lisca Bianca, Bottaro, Lisca Nera, and Dattilo [12]. The "degassing crisis" lasted several months and killed all the living matter in the submarine area [13].…”

“…The main exhalative field falls within the area of the minor islets (Bottaro, Dattilo, Lisca Nera, Lisca Bianca, and Panarelli; Figure 1) about 2 miles to the east of the main island [17]. The Panarea hydrothermal field has extensively been investigated for many different reasons (e.g., in [13]): it represents an important natural laboratory in order to better understand the processes governing the thermal fluid migration from the deep reservoir to the seafloor, the impact of an active hydrothermal system on the seafloor ecology, the role of bubbling and dissolved CO 2 on the living matter, and the contribution of natural gas emissions to the ocean acidifications. The geochemical features of the hot fluids provide important information on several interactions among seawater, meteoric water, magmatic gases, and hosting rocks, and they help in defining the relationship between the hot deep source and its surrounding area.…”

Geochemical and Geophysical Monitoring of Hydrocarbon Seepage in the Adriatic Sea

“…The measurements of dissolved benthic fluxes at the sediment-water interface are fundamental to better understand the marine biogeochemical cycles and alterations of aquatic ecosystems, as a consequence of human activities or natural processes [34]. Benthic fluxes are the dissolved chemical substances released or absorbed by the seabed as a result of early diagenesis processes or volcanic and hydrothermal/hydrocarbon release processes [35].…”