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Discovering deep Ponza

Tuesday, 9 September, 2014

On the 20th of August 2014, the ECOSAFIMED scientists Marzia Bo and Sandro Cerasi, from the University of Genova, and Jordi Grynyo, from the Superior Council of the Scientific Investigation of Barcelona, joined the crew members of the oceanographic vessel Astrea and the marine biologist Simonepietro Canese from ISPRA in the harbor of Formia, close to Rome. Direction: Ponza Island, the largest of the Italian Pontine Islands archipelago, located 33 km south of Cape Circeo in the Tyrrhenian Sea.

Our mission was to complete an oceanographic survey, comprehensive of both high resolution topographic mapping and ROV investigations, of the Pontine study area, including Ponza, Zannone and Palmarola islands. Based on previous investigations with local fishermen, seven different fishing grounds were identified in the area, large territories exploited by the artisanal fishing fleet of Ponza, targeting lobsters, cods and mullets. Our goal was to map the areas and find evidences of benthic communities composed of structuring species, such as corals, sponges and bryozoans, that are the most sensitive to the impact of demersal fishing gears such as trammel and gillnets. Various ROV dives were planned between 50 and 200 m depth in order to characterize the benthic communities and put in evidence potential impacts of both different gears in areas subjected to different fishing effort.

A total of 20 dives were carried out in the study area between the 20th and the 27th of August. 21 ROV transects (corresponding to over 13000 m of linear ground explored) were carried out for a total of over 25 hours of video footage and about 2100 high resolution photographs. Some very interesting coral communities were reported in this survey, among all important black coral forests composed of dozens of Parantipathes larix colonies, a bottle-brush coral as tall as a young boy. Other black coral species were reported throughout the entire study area in numerous localities. Various patches of red coral, as well as interesting sponge grounds, shallow water gorgonian forests, and meadows of small tube anemones were documented. These findings are particularly relevant due to the fact that, in the Tyrrhenian Sea, the area of Ponza, despite representing a crucial cross-way and despite its peculiar geological characteristics, has never been explored before and these data represent the first footage for this zone. Important traces of fishing impact, attributable not only to professional gears but also to recreational ones were detected in all sites. Lost gears, such as pieces or whole nets, lost long lines, and general litter were occasionally found on the rocky hardgrounds within the fishing grounds, at times directly entangling the coral colonies. A major work of data analysis to be carried out in the near future will help us to delineate a general picture on the distribution of the benthic communities in Ponza and on the major sources of impact in order to define the most suitable conservation strategy for the area.

A great help was given by the local fishermen community collaborating not only during the first phase of interviews and experimental hauls, but also during the oceanographic survey, by coming on board and indicating sites known to be common for gears’ entanglement on the bottom and on the benthos.

The next goal will be to complete the other programmed oceanographic survey in the second study area, Patti (Sicily).