Diatom community structure and morphotype classification were studied and periphyton biomass, course particulate organic matter (CPOM), hydrogeomorphological parameters, and nutrient concentrations were measured at 4 stations downstream of the Cecita dam (Mucone River) and at 3 control sites located on different tributaries of the Mucone River in May, August, and November 2005. The lowest values of current velocities and the highest amounts of sand deposition and CPOM accumulation were detected at the stations closest to the dam. Downstream, the confluence with the first permanent tributary (Cerreto River) of the Mucone showed a "rhythral" morphology, similar to that of the control sites. Multivariate analysis showed that the community was constantly segregated into 2 groups: G1 (stations upstream of the Cerreto inflow), dominated by early colonizers, adapted to both high and low current velocity and tolerating burial and light deficiencies; and G2 (all other stations), where the prevailing taxa were species typical of stable environments with high values of flow and abundance of coarse substrates. Genus-based morphotype classification failed to detect any differences between the 2 groups. Biomass levels were higher at station G2 than G1, while accumulation of CPOM downstream of the reservoir promoted fine particulate organic matter production and a switch from autotroph to heterotroph dominated biofilms.

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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.

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Changes in the benthic macroinvertebrate community in the Arente River (a tributary of the Crati river in the Region of Calabria, Italy) were monitored monthly for 1 year through stratified sampling by habitat (pools and riffles) together with general descriptors of communities structure and the extended biotic index (EBI) to assess the potential development of community alteration following strong hydrological increases. Results suggest that flow peaks and substratum instability remarkably affect population abundance and composition of macroinvertebrate assemblages in both macro-habitats whereas their ordination is due to chemical parameters analyzed only at low water periods. Organism and taxonomic densities as well as taxonomic richness all showed an appreciable reduction simultaneously with flow increases both in pools and riffles. Early colonizers (organisms with high dispersal and drifting tendency) dominate during hydrological perturbation and post-perturbation phases. Both EBI and environmental quality values more frequently show the development of river disturbance in pools than in riffles during and after flow changes. Regression analysis clearly shows that hydrological and substrate parameters are better predictors of community parameters changes (higher r(2) values) in pool habitats than in riffles habitats suggesting that depositional environments seem more suitable than erosive ones in monitoring macrobenthic community changes and, possibly, alterations due to hydrological variations.