Trophic status and phytoplankton in Lake Bidighinzu

From March 1988 to April 1989 a survey was carried out on the phytoplankton of Lake Bidighinzu, a hypertrophic reservoir in Northern Sardinia. The purpose of this work was to assess the general limnological conditions of the reservoir after a diversion of the urban and industrial wastes. The dynamics of chlorophylla, and the structure and composition of the phytoplankton density and of its biomass in the study period were determined. Moreover the found trends for trasparency, temperature, conductivity, alkalinity, pH, dissolved oxygen, reactive and total phosphorus, nitrate, nitrite, ammonium nitrogen, and reactive silica are reported. The effect of water aeration on the dynamics of the other parameters is discussed

The Trophic status of Bidighinzu Reservoir (Sardinia) before and after the diversion of waste waters

The purpose of this paper was to assess the effect of the diversion of wastewater on the trophic status of Lake Bidighinzu, a hypertrophic man-made lake in Northern Sardinia, used as a drinking water reservoir. There have been problems with potabilization since the early years of the diversion operation, particularly in the summer-autumn period. Data available (August 1978, February 1979 and March 1985) before the reservoir (1987) were compared with those collected during a study carried out in the annual cycle immediately after (1988-1989) and after some years (1994 and 1996-1997). The study examined the dynamics of temperature, main nutrients (total phosphorus, nitrate and ammonia), chlorophyll-a and phytoplanktonic biomass. No particular variation in the water nutrient availability emerged from the comparison between these two situations - especially for total phosphorus, whose annual mean concentrations were similar in the two annual cycles (386 mg P m-3in 1988-1989 and 305 mg P m-3in 1996-1997). Chlorophyll- a and biomass were high during each period of study (annual mean values were 17 mg m-3and 3.7 mg l-1in 1988-1989 and 11 mg m-3and 4.6 mg l-1in 1996-1997). However, peaks were never higher than values recorded in August 1978 (112 mg m-3and 133 mg l-1) due to an extraordinary bloom ofCeratium hirundinella(O.F. Müller). Species composition of phytoplankton was typical of highly trophic conditions and was frequently characterised by the presence of Cyanophyceae and Bacillariophyceae. Results demonstrated that, ten years after construction of the by-pass, the lake had shown no improvement in its trophic status. This might depend on many factors, among which the most likely might be the non-use or partial use of the diversion system, which allows the sewage to continue to flow into the lake and keep its trophic status almost unchanged

The Dominance of cyanobacteria in Mediterranean hypereutrophic lagoons: a case study of Cabras Lagoon (Sardinia, Italy)

An intense proliferation of cyanobacteria in Cabras Lagoon was investigated over a period of two years (July 2007 to June 2009). The influence of environmental and meteorological parameters in the lagoon on temporal variations in cyanobacteria orders was assessed. For 17 months, Chroococcales was the only cyanobacterial order observed in the lagoon.Cyanobium-type cells (Reynolds functional group Z) were the most abundant phytoplankton taxon during this period. In the following months, drastic changes in the cyanobacteria assemblages occurred simultaneously with constant, intense rainfall that led to a sudden drop in the lagoon’s salinity. The succession of autumn–winter Oscillatoriales (Planktothrixsp. andPseudanabaena catenata; Reynolds functional group S1) and late spring growth of Nostocales (Aphanizomenon gracile,Aphanizomenon aphanizomenoides, andAnabaenopsis circularis; Reynolds functional group H1) was monitored. Canonical Correspondence Analysis was carried out to quantify the influence of environmental variables, and indicated strong relationships between Chroococcales and salinity, Oscillatoriales and higher values of SRP and the DIN/SRP ratio, and Nostocales and lower nutrient concentrations, the DIN/SRP ratio and salinity

A Numerical index for evaluating phytoplankton response to changes in nutrient levels in deep Mediterranean reservoirs

This paper proposes a new ecological index based on phytoplankton (MedPTI) as suggested by the European Directive 2000/60/CE, Water Framework Directive (WFD). The index is a useful tool to verify the impacts of eutrophication in Mediterranean reservoirs belonging to different categories of the WFD. Multiple data sets were employed to develop the MedPTI index. The calibration data set included data collected from 30 Sardinian reservoirs in 1994. A list of 44 selected taxa was obtained and used for index calculation. A second dataset including 48 averaged annual values from 10 reservoirs was used. Results showed good correlation between MedPTI and concentration of total phosphorus, which was the limiting nutrient in these reservoirs. The trophic classifications determined using the index agreed with the results from the OECD probabilistic model on the same series of data. Finally, the index was included in an international exercise to compare the definition of reference conditions and quality class boundaries against indices used in other Mediterranean countries

Effects of trophic status on microcystin production and the dominance of cyanobacteria in the phytoplankton assemblage of Mediterranean reservoirs

The aim of our study was to evaluate the abundance of cyanobacteria and microcystins in four Sardinian reservoirs (Italy) characterised by different trophic status to define a reference picture for future changes. Increasing levels of eutrophication and the abundance of cyanobacteria are expected to occur due to climate change, especially in the southern Mediterranean. Consequently, an in-depth study of the occurrence of harmful cyanobacteria is important to develop appropriate management strategies for water resources at a local scale. Monthly samples were collected at one station in each reservoir over an 18-month period. The Analysis of similarity indicated that cyanobacterial abundance and species composition differed significantly among the reservoirs. The Redundancy analysis highlighted their relationship to trophic, hydrological and seasonal patterns. Spearman’s analysis indicated that there were significant correlations among the most important species (Planktothrix agardhii–rubescens group, Aphanizomenon flos-aquae and Dolichospermum planctonicum), nutrients and microcystins. We highlighted that the species composition during periods of maximum microcystin concentrations differed from those typically reported for other Mediterranean sites. We found new potential microcystin producers (Aphanizomenon klebahnii, Dolichospermum macrosporum and Dolichospermum viguieri), which emphasised the high diversity of cyanobacteria in the Mediterranean area and the need for detailed research at the local scale

Heavy metals: teeth as environmental biomarkers

Aim of this study was to measure the concentration of heavy metals in tooth matrix and to determine the factors that affect their presence. During tooth development and mineralization several metals can be absorbed in the tooth matrix, thus allowing us to use them as biological markers

Studi limnologici sul Lago Alto Flumendosa (Sardegna centrale): stato trofico e fitoplancton

Alto Flumendosa Reservoir (Central Sardinia), was investigated from February 1990 to February 1993, to study either long time period phytoplankton variations in a mesotrophic mediterranean reservoir and to value the influence of a cage rearing pisciculture on its trophic status. The annual mean values of clorophyllavaried from 2.3 mg m-3in 1991 to 11.1 mg m-3in 1990, annual mean values of biomass from 0.5 mg l-1in 1993 to 3.9 mg l-1in 1990 and annual mean values of cellular density from 6 x 106 cells l-1in 1993 to 11.3 x 106 cells l-1in 1990. Despite great variations in the species composition of phytoplankton in each year, a general scheme in the algal succession was found with Cryptophyceae in the colder months, Chlorophyceae in the spring months (sometimes in autumn), Cyanophyceae and Dinophyceae in summer, Bacillariophyceae in autumn, Chrysophyceae between winter and spring and Conjugatophyceae in summer or in winter. The trophic status on the basis of phytoplankton composition, clorophylla, annual mean values of total phosphorus (from 19 mg P m-3in 1993 to 25 mg P m-31990) was mesotrophic but in 1990 the eutrophic probability, on the basis of chlorophylla, was higher. The cage rearing pisciculture was presumed to be responsible of the strong oxygen decreases in hypolimnetic water at the end of the stratification periods

Molecular identification of Mycobacterium avium subspecies paratuberculosis in oral biopsies of Crohn’s disease patients

Oral lesions may be found in patients with Crohn’s disease (CD), in a percentage up to 20%. The aim of this study was to investigate a possible relationship betweenMycobacterium aviumsubsp.paratuberculosis(MAP) and oral lesions in CD patients. 23 oral biopsies were examined performing IS900Nested PCR; 9 of them were positive: 8 from CD patients and 1 from a control. Our purpose is to go on with this study, amplifying the number of subjects examined and testing subjects with oral lesions related to diseases other than CD to verify the specific association between MAP and oral lesions in CD patients

Multifunctionalization of wool fabrics through nanoparticles: a chemical route towards smart textiles

A new approach towards the design of smart nanotextiles with innovative properties is presented. Silica (SiO2), titania (TiO2), and silver (Ag) nanoparticles (NPs), were synthesized without the use of any toxic organic compound and then were used, alone and in combination, to functionalize wool fabrics. Electrostatic forces, influenced by a low pH of the solutions, allowed the interactions between wool fabrics and NPs, enabling a robust functionalization. This was verified by X-ray microfluorescence and visualized by scanning electron microscopy measurements. The antibacterial Ag NPs were embedded in a polymer, alginic acid, to reduce the possible side effect due to their direct contact with the skin. SiO2 NPs, instead, were used to change the hydrophilicity of wool while the functionalization with TiO2 NPs was chosen to provide self-cleaning properties. The antibacterial activity of the fabrics was studied against the bacteria Escherichia coli, while the hydrophilicity of wool was studied by contact angle measurements and the self-cleaning properties were tested by estimating the visible discoloring of a dye stain under sunlight irra- diation. Interestingly the combination of three different types of NPs provided the best results. SiO2 and Ag made the wool superhydrophilic providing at the same time the best antibacterial properties, while fabrics with titania (alone or in combination) were hydrophobic and showed the best self-cleaning properties

Variabilità spazio-temporale della struttura del fitoplancton nel Golfo dell'Asinara (Sardegna) = Spatial and temporal variability of phytoplankton structure in the Asinara Gulf (Sardinia)

The spatio-temporal variability of phytoplankton and some environmental parameters in the gulf of Asinara are examined (05/97-04/98). Along the whole coastal area, stations at 500 and 3000 mfrom coast across 6 transects are considered. Results point out some variations in phytoplankton composition and dynamics. Multidimensional Scaling ordinations and Bray-Curtis cluster analuses identified two major zones at 500 m from coast, one for the site of Lu Bagnu and one for the other five sites; at each stations, a great similarity was found in its respactive share. On the contrary, at 3000 m from coast, no cluster was identified