Biological and chemical monitoring of some major Calabrian (Italy) Rivers.

To address the problem of whether hydrographic basins of southern Italian regions such as Calabria are exposed to "ecological stability pressures," we here provide the first results of four chemical and biological (macroinvertebrates) monitoring activities. The data accumulated within four hydrographic basins between May and November of 2002, November of 2005 and May of 2006 showed that about 1/3 of the macrobenthos sampled among a total of 14 rivers in the northern-central part of Calabria region provided optimal environmental quality values of Extended Biotic Index (E.B.I.), 1/3 denoted a slight impairment and the remaining samples exhibited very strong environmental alterations. It is interesting to note that E.B.I. is directly correlated with the taxonomic richness plus abundance, and inversely with the dominating taxon. This suggests that high environmental quality values are rather positively correlated with spatial heterogeneity and taxa eveness. In addition, the more compromised stations were located on plain segments where anthropization is reported to be at its highest level and there the macrobenthic communities seem to be made up of mostly potamon type of taxa with a high abundance of collector euriecious organisms while better quality stations, mostly located at high altitude, are characterized by a considerable presence of E.P.T. taxa. Chemical parameters did not result to be substantially altered underling that the hydrologic and geomorphological alterations may play a primary role in the control of macrobenthic communities and environmental quality. Overall the above results suggest that E.B.I. variations seem to be highly coherent with changes of main biodiversity parameters and their joined application is an efficient tool for detecting ecological state alterations of lotic environments.