Seabed of the Gulf of Custonaci (ITA010025)
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Seabed of the Gulf of Custonaci

Site type: SIC - Site of Community Interest 

Code: ITA010025 - Hectares: 4443


The Gulf of Custonaci falls on the large continental shelf of western Sicily, whose geological landscape is characterized by dolomitic limestone from the Tertiary, alternating with shell-like calcarenite tuff from the Quaternary. The reliefs of Monte Cofano and Monte S. Giuliano are a reference point of the plains of Bonagia and Cofano, of the soft internal hills. Monte Cofano advances into the sea forming the Gulf of Cofano to the east, a natural basin overlooked by the plain of Castelluzzo, and the Gulf of Bonagia to the west which opens onto the homonymous wide limestone plain closed to the west by the relief of Monte S. Giuliano.The morphology of the coast is articulated by the presence of numerous inlets, peaks and promontories, cliffs, rocky escarpments, limestone plateaus and narrow beaches limited by terraced slopes.The submerged area is generally covered by an important posidonia, and in large tracts overlooking the sawmills and the marble quarries, depending on the contribution of processing residues, sedimentation facies characterized by galenophilic and psammophilic species have been established.The stretch of coast at the base of Mount Cofano is characterized throughout the infralittoral from the biocenosis to photophilic algae with dominance of the succession to Fucales (Cystoseira spp.), with the belt to Cystoseira amentacea var. stricta to border the mesolittoral; sometimes these Feoficee are vicariates from algae typical of well-lit environments, such as Padina pavonica and Acetabularia acetabulum, which always settle on a hard substrate. A greater depth is followed by a vast Posidonia oceanica prairie, which grows mainly on rock and which beyond the 30 meter bathymetric depth is replaced by precoralligenous and coralligenous concretions, particularly rich in algae such as Halimeda tuna and Flabellia petiolata and filter feeders. close to the inhabited center of Bonagia, the photophilic biocoenosis is replaced by well-calibrated fine sands which in some areas extend up to the 25-meter bathymetric depths. to Astroides calycularis, the submerged ravines and the sciaphilous populations and the Posidonia oceanica meadows. The vermeti sidewalk, a biogenic construction due to the sessile gastropod Dendropoma petraeum, is particularly extensive and with an excellent level of structuring, especially along the coastal strip near Mount Cofano. The strip of Astroides calycularis, a thermophilic colonial madreporary, in regression in many areas of the Mediterranean, covers the shaded hollows of the infralittoral immediately below the worm-covered pavement. Both Dendropoma petraeum and Astroides calycularis are among the endangered or endangered species in the Mediterranean. The superficial caves and the intense karst are the most expressive landscape aspect of the carbonate nature of the substrates of the coastal strip of the area. The presence of limestone also increases the settlement of meroplankton larvae and the formation of shelters occupied by a rich endolithic fauna. The Posidonia oceanica meadows, a priority habitat, represent the most important biocenosis as they are particularly abundant and distributed in a rather continuous manner over all the sea beds of the area, showing limited erosion areas, with mainly continuous distribution, and planted more than anything else on rock and matte.The prairie shows a lower limit mainly of a progressive type with isolated colonies on a rocky bottom at depths between 31-36 m and sandy between 34-38 m. Sometimes the limit is of the net type of substrate at 32 m with the prairie implanted on rock which stops when the seabed becomes sandy. The submerged base of Mount Cofano forms, 500 m offshore, the "edges of the Cofano" about 35 m deep and called "Secche del Saraceno", an ancient coastline that is now submerged. Once on its walls, red coral worked by Trapani artisans was fished.

The entire area is of very considerable importance from a biological and environmental point of view. In the seabed, X Back to top X Back to top there are various animal species that appear in the lists of species to be protected, as required by national and international conventions. The presence of vast Posidonia oceanica meadows, an important nursery area for fish species, together with the belt of Astroides calycularis, and the concretions represented by the sidewalk with vermetid molluscs (Dendropoma petraeum) complete the peculiarities of this environment.

Source: Ministry of the Environment Natura 2000 form

Ministerial data: Ministerial Map  Natura 2000 form

Card insertion: Ignazio Caloggero

Photo: web

Information contributions: Ignazio Caloggero, Region of Sicily

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