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Lai G.G.,University of Sassari | Padedda B.M.,University of Sassari | Pulina S.,University of Sassari | Virdis T.,ENAS Ente Acque della Sardegna | And 2 more authors.
Vie et Milieu | Year: 2010

Eight watercourses in North-Central Sardinia were studied between 2008 and 2009 to ascertain their environmental quality and to gain insights into the requirements for their proper management. In addition to physicochemical and microbiological parameters, epilithic diatoms were analyzed at 15 stations. Data on the diatom community of each sample were used to calculate the diatom-based eutrophication/pollution index (EPI-D) and the biological diatom index (IBD). In the 21 collected samples, 153 taxa belonging to 36 genera were identified, but the diatom flora also included species that could not be determined with certainty. Most of the observed diatoms are considered cosmopolitan and were common to various sites, with Cocconeis placentula var. pseudolineata and Diadesmis confervacea among the most frequent and sometimes the most abundant taxa. Platessa hustedtii, which like Diadesmis confervacea is considered a tropical species, was recorded for the first time in Sardinia. While these species are not considered by the EPI-D proposed for use in Italian watercourses, their integration will improve the usefulness of this index in the assessment of islands of Mediterranean typology. The applicability of the EPI-D and IBD was confirmed with water quality at nearly all the considered stations ranging from mediocre to bad according to both indices. Moreover, these results were supported by physicochemical and microbiological variables and were consistent with the typology of the investigated environments.

Padedda B.M.,University of Sassari | Sechi N.,University of Sassari | Lai G.G.,University of Sassari | Mariani M.A.,University of Sassari | And 6 more authors.
Ecological Engineering | Year: 2015

With many lakes and other inland water bodies worldwide being increasingly affected by eutrophication resulting from excess nutrient input, there is an urgent need for improved monitoring and prediction methods of nutrient load effects in such ecosystems. In this study, we adopted a catchment-based approach to identify and estimate the direct effect of external nutrient loads originating in the drainage basin on the trophic state of a Mediterranean reservoir. We also evaluated the trophic state variations related to the theoretical manipulation of nutrient inputs. The study was conducted on Lake Cedrino, a typical warm monomictic reservoir, between 2010 and 2011. We assessed the hypereutrophic condition of the reservoir by monthly samplings of the water column and compared these results with the amount of nutrient load originating from anthropic activities in the drainage basin [42.6tPy-1 for total phosphorus (P) and 531tNy-1 for total nitrogen (N)]. We verified how the predictive OECD management model could be confidently applied to predict the P concentration in the reservoir on the basis of estimated loads from the drainage basin (98.7mgPm-3 assessed versus 101mgPm-3 estimated, approximately 2.5% over). Different scenarios are presented showing how it is possible to reduce approximately 62% P and 43% N, altering the condition of the ecosystem to become more mesotrophic. We also propose some management strategies to improve water quality in this lake ecosystem. © 2015 Elsevier B.V.

Pulina S.,University of Sassari | Suikkanen S.,Finnish Environment Institute | Satta C.T.,University of Sassari | Mariani M.A.,University of Sassari | And 5 more authors.
Plant Biosystems | Year: 2014

We investigated multiannual trends in phytoplankton in relation to several environmental drivers. We analyzed ecological data collected during the past two decades from three aquatic sites: an artificial lake, a coastal lagoon, and a marine coastal area. Hydrographic, nutrient, and phytoplankton data were statistically analyzed to detect trends and interactions. In all ecosystems, the chlorophyll a concentration decreased with increasing abundance of small-sized phytoplankton. Phytoplankton dynamics were related to decreased nutrient concentrations in the lake, to dynamics of phosphorus and decreased salinity in the lagoon, and probably to combined top-down and bottom-up processes in the marine gulf. © 2014 Società Botanica Italiana

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