S Chiesa

OCCURRENCE OF ALLOCHTHONOUS FRESHWATER CRAYFISHES IN LATIUM (CENTRAL ITALY)

The introduction of animal species, transfaunation and habitat destruction are among the greatest threats for biodiversity. In fact, in the water systems of Latium the occurrence of allochthonous crayfishes Procambarus clarkii, Orconectes limosus and Astacus leptodactylus has been observed. The distribution of these species in Latium highlighted some differences between them: Orconectes limosus and Astacus leptodactylus are present in restricted areas, while Procambarus clarkii has a wide distribution throughout the region. The present study confirmed their ecological plasticity, strong capability of invasion and adaptation to new environments of all three species, due to their rapid growth, utilisation of different trophic resources and the frequency and length of their reproduction periods. These aspects can cause irreversible ecologic and economic damage. The eradication of Procambarus clarkii would be a difficult task, because of its wide distribution and the many records of the species, especially in the Province of Latina, where complex field irrigation systems are found. All the agencies for environmental protection should increase control activities, with a serious field effort. As regards the other two species, eradication would be easier due to their limited distribution. It is important to avoid the spreading of these species; this can be done through public opinion awareness-raising campaigns and a continuous control on the region, increasing research and supporting it with new laws concerning the introduction and treatment of alien species.