| Text | 329191 2012 Fitoplancton Macrofite Laghi Variabilita naturale e legata a fattori antropici nei siti lacustri studiati Giuseppe Morabito; Aldo Marchetto; Martina Austoni; Alessandro Oggioni; Antonella Luglie; Maria Antonietta Mariani; Bachisio M. Padedda; Nicola Sechi; Elio Sesia; Teo Ferrero; Pierluigi Fogliati; Gabriella Fornaro; Mario Pannocchia; Francesca Vietti; Marzia Ciampittiello Giuseppe Morabito1, Aldo Marchetto1, Martina Austoni1, Alessandro Oggioni1,2 , Antonella Luglie3, Maria Antonietta Mariani3, Bachisio M. Padedda3, Nicola Sechi3, Elio Sesia4, Teo Ferrero4, Pierluigi Fogliati5, Gabriella Fornaro5, Mario Pannocchia5, Francesca Vietti6 Marzia Ciampittiello1 1 CNR ISE, Verbania Pallanza VB 2 CNR IREA, Unita Operativa di Supporto, Milano 3 Dipartimento di Scienze Botaniche, Ecologiche e Geologiche, Universita di Sassari 4 ARPA Piemonte, Struttura Specialistica Qualita delle Acque, Asti 5 ARPA Piemonte, Dipartimento di Torino, Presidio Territoriale di Ivrea 6 ARPA Piemonte, Dipartimento di Biella The natural variability of the biotic components, in particular of those showing seasonal cycles, often leads to significant changes of biomass as well as specific composition. This means that the choice of sampling frequency and distribution during the year may be crucial when assessing the ecological quality of a waterbody, starting from the structure of biotic communities. Among the four biological quality elements used to classify the lakes, three of them phytoplankton, macrophytes and macroinvertebrates show a marked seasonality and/or a certain degree of spatial variability. This document has the aim to evaluate how the metrics used are sensitive to the natural variability, especially respect to their response to the pressure gradients. The analysis was carried out on data collected during the project and is limited to phytoplankton and macrophytes, because the examination of autumn samples of macroinvertebrates, is still in progress. Regarding phytoplankton, three metrics defined by Italian national legislation composition indices, chlorophyll and biovolume were analyzed, comparing the variability due to anthropogenic origin expressed by the gradient of total phosphorus with the natural one seasonal variations on different time scales and estimating the uncertainty in the classification using different sampling frequencies. In the case of macrophytes, monitoring methods and classification were analyzed respect to their accuracy in assessing if the variability between sites, explained by a different anthropogenic pressure, is actually greater than the variance within the individual lake. In addition, we want to determine if the sampling effort, as established by the monitoring protocols, is adequate to the needs of the classification. Our analysis showed that the variability of phytoplankton metrics reflects the trophic gradient and is more significant than that explained by seasonal fluctuations, demonstrating the robustness of the indicators used. Moreover, the phytoplankton assemblages reveal a high stability in interannual patterns of succession. Conversely, the general formulation of the macrophytic index may need to be redefined to better understand the differences in ecological quality between lakes. Furthermore, as concerns macrophytes, a significant reduction of the sampling effort does not seem to be possible without compromising the quality of classification, while, as regards phytoplankton, it would be acceptable to reduce the number of annual samples from 6 to 4 without compromising the result of the classification, while observing the seasonality, because our analysis suggests that phytoplankton samples concentrated in a single season lead to increased uncertainty in the classification. Deliverable del progetto INHABIT Local hydro morphology, habitat and RBMPs new measures to improve ecological quality in South European rivers and lakes Deliverable 2012_Deliverable_I1d5_INHABIT.pdf Rapporto di ricerca Research report martina.austoni AUSTONI MARTINA aldo.marchetto MARCHETTO ALDO giuseppe.morabito MORABITO GIUSEPPE marzia.ciampittiello CIAMPITTIELLO MARZIA alessandro.oggioni OGGIONI ALESSANDRO TA.P04.016.004 Ecologia teorica e applicata degli ecosistemi acquatici |
