Ecological surveys for the valorization of spring environments of Sardinia: implications for their fruition and environmental protection.

Springs are ecosystems with unique features and great ecological value. In the Mediterranean area they are more exposed to the risks of alteration of their structure and natural functioning because of direct and indirect human pressures and climate change. Despite this, springs remain poorly studied and specific approaches of management and protection are still missing. The main purpose of this PhD was to acquire knowledge on ecology of karst and thermo-mineral springs of Sardinia, traditionally neglected. The research activities focused on diatom microflora from different substrates in 17 springs of the Island. The results indicated a high diatom biodiversity, also highlighted by the presence of Sellaphora gologonica sp. nov. and Chamaepinnularia thermophila, the latter observed only in very few sites in the world so far. The analysis of the relationships between species and environmental variables, confirmed that diatoms can reflect the effects of important factors related to the vulnerability of these ecosystems, such as hydrological stability (flow permanence), discharge, climate change (extreme flash floods) and nutrient enrichment. This thesis offer food for thought on the importance of enhancing and preserving these environments so important from an ecological point of view and of so large interests for human uses. The information collected may represent a starting point for the development of strategies aimed at their proper management

Chamaepinnularia thermophila (Bacillariophyceae) : synonymy with Navicula tongatensis Hustedt and update of its geographic distribution and ecology

Abstract Chamaepinnularia thermophila is a small and poorly known diatom species. After the first description from a hot spring in Guadalupe in 1952, its presence appeared to be limited to a few other springs of the French Antilles. The objective of this study is to report new information on aspects of taxonomy, distribution and ecology of this species. Accurate analysis under light and scanning electron microscope of the material collected on different substrates (cobbles, macrophytes and fine sediments) from a thermo-mineral spring of Sardinia (Italy) allowed us to document the first record of the species in the Mediterranean area. Furthermore, the comparison with Navicula tongatensis from Hustedt's original material, carried out because of their similarity, revealed identical morphological characteristics suggesting their consequent synonymy. Based on the information available in the literature and our data, C. thermophila is a rare species present mainly in tropical areas, in thermal springs with alkaline pH, medium to high conductivity and low to moderate nutrient content. The occurrence of the species at sites with very different environmental characteristics seems unusual, but it could indicate a broader ecological range. This study contributes to the standardization of the nomenclature used for this species so far and provides the first framework on its global geographic distribution and ecology

Consequences of eutrophication in the management of water resources in Mediterranean reservoirs: A case study of Lake Cedrino (Sardinia, Italy)

Abstract One of the primary detrimental effects of eutrophication is the tendency of nuisance cyanobacterial species to increase in number and biomass in freshwater ecosystems. The aim of this study was to investigate possible management actions to control eutrophication and assure water use of a eutrophic deep Mediterranean climate reservoir, dominated by cyanobacteria. With this goal, we defined the trophic state of Lake Cedrino (Sardinia, Italy) and studied its phytoplankton, paying particular attention to cyanobacteria, and to seasonal variation of phytoplankton in relation to seasonal variation of environmental variables. The water samples were collected monthly from September 2010 to August 2011 at differing depths from the surface of the water to the bottom at a station located in the deeper portion of the reservoir. Physical, chemical, nutrient, qualitative and quantitative analyses of phytoplankton were performed, and the trophic state was evaluated based on the Trophic State Index and the OECD model. Abundance of nutrients and phytoplankton (cell density, biomass and chlorophyll a ) indicated a eutrophic condition of the reservoir. In summer, phytoplankton species composition was dominated by nuisance cyanobacteria, particularly Aphanizomenon flosaquae , thereby requiring management plans for harmful blooms. On the base of lake features, we propose management actions at different scales and levels to resolve eutrophication and to allow water use: from nutrient load reduction in the watershed (primarily from point-sources) to deep water aeration, to immediately face an attenuation of eutrophic effects. This study is the first explorative step in planning restoration of Lake Cedrino

Long-term ecological studies on phytoplankton in Mediterranean reservoirs: a case study from Sardinia (Italy)

Artificial lakes are strategic water resources in the Mediterranean region but are one of the most vulnerable areas to the impacts of climate change, particularly to the expected significant decrease in water resources; therefore, enhancing the ability of water management to improve water quality is crucial. This study contributes to the knowledge of the long-term ecological features of Mediterranean artificial lakes based on a case study of Bidighinzu Lake in Sardinia, Italy, a warm, monomitic and hypereutrophic reservoir mainly used for drinking water. Among the different restoration actions carried out in Bidighinzu Lake to improve water quality is the reduction of nutrient loads from the watershed. To study multiannual trends of the trophic state, a long-term series (1988–2012) of both environmental variables and phytoplankton was analysed. Mann-Kendall tests revealed increasing trends for total nitrogen to total phosphorus ratios (TN:TP; significant in spring, summer, and winter) and decreasing trends for ammonium (winter and autumn), TP (all seasons), orthophosphate (spring, summer, and winter), reactive silica (autumn), and pH (summer). Among phytoplankton, significant increasing trends were assessed in biomass of Bacillariophyceae, Chlorophyceae, Dinophyceae, and Chrysophyceae. Cyanobacteria did not show a clear trend, although at the order level, Chroococcales significantly increased in summer and decreased in winter. Despite these major tendencies, the lake did not show significant improvement in its eutrophic state, probably due to an inherent resistance and the insufficient and/or not well calibrated or applied recovery actions

Long-term ecological studies on phytoplankton in Mediterranean reservoirs: a case study from Sardinia (Italy)

Artificial lakes are strategic water resources in the Mediterranean region but are one of the most vulnerable areas to the impacts of climate change, particularly to the expected significant decrease in water resources; therefore, enhancing the ability of water management to improve water quality is crucial. This study contributes to the knowledge of the long-term ecological features of Mediterranean artificial lakes based on a case study of Bidighinzu Lake in Sardinia, Italy, a warm, monomitic and hypereutrophic reservoir mainly used for drinking water. Among the different restoration actions carried out in Bidighinzu Lake to improve water quality is the reduction of nutrient loads from the watershed. To study multiannual trends of the trophic state, a long-term series (1988–2012) of both environmental variables and phytoplankton was analysed. Mann-Kendall tests revealed increasing trends for total nitrogen to total phosphorus ratios (TN:TP; significant in spring, summer, and winter) and decreasing trends for ammonium (winter and autumn), TP (all seasons), orthophosphate (spring, summer, and winter), reactive silica (autumn), and pH (summer). Among phytoplankton, significant increasing trends were assessed in biomass of Bacillariophyceae, Chlorophyceae, Dinophyceae, and Chrysophyceae. Cyanobacteria did not show a clear trend, although at the order level, Chroococcales significantly increased in summer and decreased in winter. Despite these major tendencies, the lake did not show significant improvement in its eutrophic state, probably due to an inherent resistance and the insufficient and/or not well calibrated or applied recovery actions

Haplotype affinities resolve a major component of goat (<i>Capra hircus</i>) MtDNA D-loop diversity and reveal specific features of the Sardinian stock

Goat mtDNA haplogroup A is a poorly resolved lineage absorbing most of the overall diversity and is found in locations as distant as Eastern Asia and Southern Africa. Its phylogenetic dissection would cast light on an important portion of the spread of goat breeding. The aims of this work were 1) to provide an operational definition of meaningful mtDNA units within haplogroup A, 2) to investigate the mechanisms underlying the maintenance of diversity by considering the modes of selection operated by breeders and 3) to identify the peculiarities of Sardinian mtDNA types. We sequenced the mtDNA D-loop in a large sample of animals (1,591) which represents a non-trivial quota of the entire goat population of Sardinia. We found that Sardinia mirrors a large quota of mtDNA diversity of Western Eurasia in the number of variable sites, their mutational pattern and allele frequency. By using Bayesian analysis, a distance-based tree and a network analysis, we recognized demographically coherent groups of sequences identified by particular subsets of the variable positions. The results showed that this assignment system could be reproduced in other studies, capturing the greatest part of haplotype diversity. We identified haplotype groups overrepresented in Sardinian goats as a result of founder effects. We found that breeders maintain diversity of matrilines most likely through equalization of the reproductive potential. Moreover, the relevant amount of inter-farm mtDNA diversity found does not increase proportionally with distance. Our results illustrate the effects of breeding practices on the composition of maternal gene pool and identify mtDNA types that may be considered in projects aimed at retrieving the maternal component of the oldest breeds of Sardinia.</br

HBV DNA suppression and HBsAg clearance in HBeAg negative chronic hepatitis B patients on lamivudine therapy for over 5 years

BACKGROUND & AIMS: In long-term responder patients, it is unclear whether lamivudine (LAM) monotherapy should be continued or switched to a high-genetic-barrier analogue. This study aims at assessing LAM efficacy over a 5-year period and the residual risk of drug resistance. The rate of HBsAg clearance and LAM long-term safety profile were also evaluated. METHODS: One hundred and ninety-one patients with chronic HBeAg-negative hepatitis B successfully treated with LAM monotherapy for at least 5years were included. Biochemical and virological tests were assessed every 3months in all patients and HBsAg quantification was performed in 45/191. Reverse-transcriptase (RT) region was directly sequenced in virological breakthrough patients. RESULTS: One hundred and ninety-one patients (148 males, median age 53years, 72 with compensated cirrhosis) responding to 60-month LAM monotherapy continued to receive LAM monotherapy beyond the initial 5years and were followed for an additional 36-month median period (range 1-108). Virological response was maintained in 128/191 patients (67%) and HBsAg clearance was observed in 15/128 (11.7%) after a 32-month median period (range 1-65). The 63 remaining patients (33%) showed virological breakthrough after a 15-month median treatment (range 1-78). RT region analysis was performed in 38/63 breakthrough patients and LAM resistant mutations were found in 37/38. No significant side effects were observed. CONCLUSIONS: In long-term responder patients, continuation of LAM monotherapy resulted in persistent viral suppression in most cases with undetectable HBV DNA by real-time PCR; moreover, 11.7% of these patients cleared HBsAg. Selection of LAM resistance, however, can still occur even after successful long-term therapy, thus emphasising the importance of a careful virological monitorin

Haplotype Affinities Resolve a Major Component of Goat (Capra hircus) MtDNA D-Loop Diversity and Reveal Specific Features of the Sardinian Stock

Goat mtDNA haplogroup A is a poorly resolved lineage absorbing most of the overall diversity and is found in locations as distant as Eastern Asia and Southern Africa. Its phylogenetic dissection would cast light on an important portion of the spread of goat breeding. The aims of this work were 1) to provide an operational definition of meaningful mtDNA units within haplogroup A, 2) to investigate the mechanisms underlying the maintenance of diversity by considering the modes of selection operated by breeders and 3) to identify the peculiarities of Sardinian mtDNA types. We sequenced the mtDNA D-loop in a large sample of animals (1,591) which represents a non-trivial quota of the entire goat population of Sardinia. We found that Sardinia mirrors a large quota of mtDNA diversity of Western Eurasia in the number of variable sites, their mutational pattern and allele frequency. By using Bayesian analysis, a distance-based tree and a network analysis, we recognized demographically coherent groups of sequences identified by particular subsets of the variable positions. The results showed that this assignment system could be reproduced in other studies, capturing the greatest part of haplotype diversity

Benthic diatoms as indicators of biological quality and physical disturbance in Mediterranean watercourses: a case study of the Rio Mannu di Porto Torres basin, northwestern Sardinia, Italy

This study focused on expanding existing knowledge about benthic diatoms and their use as indicators of biological quality and physical disturbance in six Mediterranean watercourses within the Rio Mannu di Porto Torres basin in northwestern Sardinia, Italy. Benthic diatoms were collected from 11 stations during a 1-year cycle from summer 2010 to summer 2011. The Eutrophication/Pollution Index – Diatom-based (EPI-D) was used to evaluate biological quality, and the Navicula Nitzschia Surirella Index (NNS’) was used to estimate the degree of physical disturbance at each station. In addition, physico-chemical variables and Escherichia coli were measured and analyzed each month. In total, 193 diatom taxa were identified, of which 157 belonging to 57 genera were present in the counts and were used to calculate the diatom indices. Five taxa were recorded for the first time for Sardinian watercourses; of which, Amphora paraveneta Lange-Bertalot, Cavacini, Tagliaventi &amp; Alfinito, Fallacia pygmaea ssp. subpygmaea Lange-Bertalot, Cavacini, Tagliaventi &amp; Alfinito and Diploneis spec. (aff.?) modica Hustedt are biogeographically relevant, while Navicula kotschyi Grunow and Reimeria uniseriata Sala, Guerrero &amp; Ferrario are of particular interest as exotic species with relatively restricted distribution. The EPI-D revealed mediocre and bad water quality for all the investigated stations, in agreement with the environmental variables and the heavy anthropogenic use of the study area. The EPI-D was effective at inferring the biological quality of the studied watercourses, although some of the species that were found (7% of the total) are not included in the method. We suggest including these species in the list to improve the performance of the index in Mediterranean rivers. A comparison between the results obtained by the EPI-D and seven other European diatom indices was made. Significant statistical correlations between the EPI-D and four of these indices were observed. The NNS’ was applied for the first time to Sardinian watercourses and it indicated a significant degree of physical disturbance at nearly all the stations, due to seasonal fluctuations in water flow, which are typical of the Mediterranean climate, combined with the effects of human activities

Land-Based Impact of Nutrient Loads and Eutrophication on an Ancient Mediterranean Natural Lake

In water management plans, all human impacts on the aquatic environment are quantified and evaluated. For this purpose, lake-related assessment methods of watersheds are needed. The aim of this study is to present the environmental condition along the watershed&ndash;lake continuum of Lake Baratz, located in the northeastern part of Sardinia. We provide a method to evaluate the impact of a small watershed area on the trophic state of this ancient Mediterranean natural lake. This study demonstrates the potentialities of coupling simple land structure-based models with empirical ones, allowing one to hierarchize, interpret, and predict the relationships among the watershed ecological unity and lake trophic conditions at multiple spatial and temporal scales. It also demonstrates how the impact of single and interacting nutrient stressors can have a different impact on the trophic status which, in particular, applies to autotrophs, constituting a key response in the ecosystem. We suggest that the stressor hierarchy should be considered as a way of prioritizing actions in the cost-effective implementation of conservation and management plans