Functional Evaluations in the Monitoring of the River Ecosystem Processes: The Adige River as a Case Stu

Abstract

A model of analysis and environmental evaluation was applied to 11 stretches of the Adige River, where an innovative procedure was carried out to interpret ecological results. Within each stretch, the most suitable methods were used to assess the quality and processes of flood plains, banks, water column, bed, and interstitial environment. Indices were applied to evaluate the wild state and ecological quality of the banks (wild state index, buffer strip index) and the landscape quality of wide areas of the fluvial corridor (environmental landscape index). The biotic components (i.e., macrozoobenthos, phytoplankton and zooplankton, interstitial hyporheic fauna, vegetation in the riparian areas) were analysed by both quantitative and functional methods (as productivity, litterprocessing and colonisation). The results achieved were then translated into five classes of functional evaluation. These qualitative assessments have thus preserved a high level of precision and sensitivity in quantifying both the quality of the environmental conditions and the integrity of the ecosystem processes. Read together with urban planning data, they indicate what actions are needed to restore and rehabilitate the Adige River corridor.

Leaf Litter Breakdown Processing in the Functional Monitoring of a Mountain Stream

“…The translation in quality classes of the quantitative data obtained by different analysis, according to the method proposed by BRAIONI et al (2002), gives the results reported in Table 6. Macroinvertebrate biodiversity is generally good, in agreement with the hydromorphological features of the stream bed (II class) and with the banks quality (II class).…”

“…We also examined in all the three stations: 1) the biological quality by the Extended Biotic Index (I.B.E. by GHETTI, 1997), as demanded by the Italian Law 152/99 (G.U.,1999); 2) the morpho-hydrological quality of the stream bed (BRAIONI et al, 2002); 3) the structure and composition of the macrobenthos, by its quantitative analysis (QAM); 4) the capacity of the banks to filter and buffer the nutrients and the pollutants conveyed by the river or percolating into the stream from the surrounding territory by the Buffer Strip Index (BRAIONI et al, 2000;BRAIONI et al, 2001;BRAIONI et al, 2002); 5) the capacity of the banks to support a high level of biodiversity, by the Wild State Index (BRAIONI et al, 2000;BRAIONI et al, 2001;BRAIONI et al, 2002).…”

“…Nine microhabitats occurring in the three stream sections of 250 m length each, were sampled with replicates. The macroinvertebrates sampled in each habitat were identified (BRAIONI et al, 2002), reckoned and assigned to five functional feeding groups (MERRITT and CUMMINS, 1996). Their biomass was measured after drying at 105 C°for 48 h by an analytic balance (± 0.01 mg).…”

“…The results achieved by the QAM, ALP, NLP and AIS were translated into five classes of functional evaluation according to the method described by BRAIONI et al (2002), referring to the mean values of Diversity (n°of taxa), Density (n°org./m 2 ), Density of EPT taxa, Biomass (mg/m 2 ), Contribution in biomass of the functional feeding groups, Diversity Index (H'), Homogeneity Index (H max), J Index (H'/H max), Richness (D) and to the trend of the processes of ALP, NLP and AIS colonization (BRAIONI et al, 2002).…”

“…The analysis of colonization and breakdown processes, together with other methods applied in a model of analysis and environmental evaluation on the Adige River and its fluvial corridor (BRAIONI et al, 2002), showed: 1) the high informative value of leaf litter breakdown and invertebrates colonization processes; 2) their additional informative value compared with that obtained from the usual biological, qualitative-structural streams monitoring that uses benthic invertebrates as indicators of environmental quality (BASS and HARREL, 1980;GAUFIN and TARZWELL, 1952;NELSON, 2000); 3) the complementarity between the informative value of breakdown and colonization processes and that of other functional-quantitative methods; 4) the possibility of translating results, by using suitable procedures, into functional monitoring, preserving a high level of precision and sensibility; 5) the important contribution of functional monitoring in defining actions of conservation and/or of restoration of the ecological status, and in further verification of the reliability of the actions themselves; 6) the necessity to include leaf litter breakdown, colonization processes and quantitative methods of functional monitoring among the most suitable tools in evaluating the ecological status, as required by the Water Framework Directive (W.F.D., 2000/60), also in designing River Basin Management Plans.…”