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Action C6 Control and eradication of the Procambarus clarkii and other NICS

The white-clawed crayfish Austropotamobius pallipes (Lereboullet, 1858) - an autochthonous species in Italy's fresh-water courses - is a crustacean with a robust look and a usually grainy carapace equipped with a pair of post-orbital combs. The natural habitat of the Austropotamobius pallipes is represented by rivers and streams with clear flowing water, characterized by high oxygen levels, hardness, presence of calcium carbonate and temperatures lower than 23°C. It prefers river bottoms covered with pebbles and slit.
Starting from the second half of the 20th century the populations of white-clawed crayfish have decreased in many Italian basins, such as the Sile river. The main threatening factor for this species is the competition with exotic species (Non Indigenous Crayfish Species - N.I.C.S.) such as: Louisiana crawfish, Procambarus clarkii (Girard, 1852); spinycheek crayfish, Orconectes limosus (Rafinesque, 1817); Turkish crayfish, Astacus leptodactylus (Eschscholtz, 1823) and signal crayfish, Pacifastacus leniusculus (Dana, 1852).
Most of these species, contrary to the Austropotamobius pallipes, has less needs and a faster growing rate, which means that it is more adaptable and less sensitive. These characteristics enable the allochthonous species to overpower and replace the autochthonous species white-clawed crayfish. There is a high risk that these alien species spread due to their great ability to adapt. P. Clarkii, for instance, can stand the almost total drying up of the water bodies and it survives in very low water, since it can also breath the aerial oxygen by exposing its gills to the air. Another problem connected with the allochthonous species is the transmutation of diseases, such as: the crayfish plague, caused by the water mold called Aphanomyces astaci; the burn spot, appearing as red-brown ulcerations of the exoskeleton; the Theolaniosi, also known as "porcelain disease" due to the milky color of the abdominal muscles, which is caused by the microsporidia Thelohania contejeani. According to the management plans of the SPA IT3240011 Sile: springs, Morgano marshes and S. Cristina, and IT3240019 Fiume Sile: Sile Morto and river course in San Michele Vecchio, the Austropotamobius pallipes was present in the Sile river and probably in some of its tributaries until fifty years ago. It seems that some remaining populations are still present in some tributaries of the Sile river; in 2004 some specimens were caught in the area of the lower Sile river in Sant'Elena. The alien species like P. clarkii are so well settled downstream of Treviso, that they have been observed in the stretches of the Sile river included between the municipalities of Silea, Casier, Casale sul Sile, Roncade and Quarto d'Altino, presence which has been confirmed by the most recent fishing map too. Several specimens of this species have been observed also in Sant'Angelo during the monitoring activities for the eel project. According to the decision of the Regional Council No. 2371, Annex A, of July 27th, 2006, the SPAs IT3240011 and IT3240019 are included in the Homogeneous Class 3, sub-classes A, B and C. One of the main conservation goals is the safeguard of the species having particular problems. In the list of these species there is also the Austropotamobius pallipes, and especially for the SPA IT3240011, the goals are the research of the species; the restoration of the water courses with elimination of the polluting elements and a pilot project for the reintroduction of the threatened species.
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