I corsi d’acqua naturali in sicilia la fauna ittica e le azioni antropiche: revisione dei dati di letteratura

Rivers are delicate ecosystems and chemical, physical, and biological indicators can be used to evaluate the health of their biological communities. The ecosystem conditions ofthe Sicilian rivers have been partially monitored during the last decades. In fact, Agenzia Regionale per la Protezione dell'Ambiente (ARPA) have conducted hydrographic surveys using chemical (e.g. presence of heavy metals) or biological indicators (i.e. diatoms, macrophytes, macroinvertebrates) along the major part of the Sicilian rivers. Despitefishfaunaisconsidered animportant bioindicator for riverecosystems their presence, distribution and abundance have been poorly investigated. This work is based on published data of freshwater fish species collected in Sicilian rivers. The presence/absence of fish species is reported only for 53 main rivers or in their tributaries. Twentynine species have been identified: 17 autochthones, 2 naturalized and 10 allochthones. Despite a significative number of autochthone species, only one belongs to secondary division, one is diadromous, one is vicariant, two are complementary (Anguilla anguilla, Salmo cetti, Saliaropsis fluviatilis, Aphanius fasciatus, Atherina boyeri) and the other 12 are considered sporadic species. This means that a low diversity in fish species has been found in Sicilian rivers. Despite everything, Sicily presents a high genetic characterization, with rare endemic species or populations;they have been strongly reduced along decades (e.g.A. fasciatus reduced by 85% in Simeto river) and have been listed in the IUCN Red List (A. angulla CR, S. cettii CR, S. fluviatilis NT). Our analysis indicates that this reduction seems strongly related to anthropic actions such as modification of channels, building of dams and introduction of many invasive species.