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 chlorophyll a, 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

From the perspective of the source. Neolithic production and exchange of Monte Arci Obsidians (Central-Western Sardinia)

The paper deals with the modes of Neolithic obsidian exploitation on the Sardinian source of Monte Arci, according to an integrated typo-technological/provenance approach. It focuses on the main changes in raw material selection and distribution criteria. Whilst from Early to Middle Neolithic they seem to have been influenced by technological and cultural factors, in Late Neolithic a dramatic shift in production behaviour is recorded. Then increased production rates are reflected in the appearance of a true structured exchange network which exerts bidirectional cultural and technological influences in the Northern Tyrrhenian region

Oral characteristics of Trisomy 8 and monosomy 18: a case report

Several reports described various mosaic chromosomal syndromes characterized by alterations originated by either an excess or deficit in the number of chromosomes. A case of mosaic trisomy 8 and monosomy 18 with significant involvement of the oral cavity is described, both in terms of general medicine and from a dental-oral perspective, and the treatment plan was planned and discussed. Regular follow-up visits enabled to verify significant improvement in all parameters of the patient’s oral health, which urged us to press on with our quest to protect the right to health of patients affected by disabilities

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-3 in 1988-1989 and 305 mg P m-3 in 1996-1997). Chlorophyll- a and biomass were high during each period of study (annual mean values were 17 mg m-3 and 3.7 mg l-1 in 1988-1989 and 11 mg m-3 and 4.6 mg l-1 in 1996-1997). However, peaks were never higher than values recorded in August 1978 (112 mg m-3 and 133 mg l-1) due to an extraordinary bloom of Ceratium 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

Santa Giusta Lagoon (Sardinia): phytoplankton and nutrients before and after waste water diversion

The purpose of this paper was to assess the effect of the diversion of waste water on the trophic status of the Stagno di Santa Giusta, a hypertrophic lagoon on the centre-western coast of Sardinia. The data available (1990, 1992-1994) before the diversion (1995) were compared with those collected from 1995 to 1999. The lagoon has an area of about 8 km2; its mean depth is about 1 m and is well mixed as regards circulation and stratification. This study examined temperature, salinity, pH, main nutrients (reactive and total phosphorus, nitrate and ammonium nitrogen, reactive silica), chlorophyll-a, phytoplanktonic density and phytobenthic biomass. A comparison of the condition of the water before and after the diversion showed that there was an insufficient reduction in nutrient concentrations. The mean concentrations of nitrate nitrogen and ammonium nitrogen fell from 33 and 87 mg N m-3, respectively, to 28 and 66 mg N m-3, respectively. There was a more marked reduction in phosphorus (from 107 mg P m-3 as reactive phosphorus and from 190 mg P m-3 as total phosphorus to 77 and 127 mg P m-3, respectively), and in reactive silica, from 3 to 1.7 mg l-1. Chlorophyll-a decreased from 11.3 to 10.2 mg m-3; the total density of phytoplankton dropped considerably, but this was due to a different species composition. Phytobenthic biomass showed no particular variations. There were no changes in trophic level, so that dystrophic crises still occurred after the diversion. The results showed that there were no substantial improvements in the trophic status of the lagoon during the years after the diversion, except for some months in 1995. A possible explanation may lie in the structure of the diversion system, which does not completely stop the inflow of sewage into the lagoon

Chert exploitation and production in Sardinia during the Neolithic

This research deals with the modes of chert exploitation in Sardinia during the Neolithic, combining information on major chert sources identified across the island with the technological analysis on several stratigraphic reliable series. It focuses on the changes in raw material selection and on the evolution of technological behaviours between the 6th and the 4th millennium BCE. The data collected in this work allowed us either to shed a light on the role this lithic resource played in the production systems of Neolithic communities in Sardinia, and to catch differences in the modes of procurement, depending on the chronology and location of the sites. During the Early Neolithic, lithic raw material circulation in Sardinia did not occur through organized networks, but it seems to have relied on the high mobility of the local groups. It is only at the end of the 5th millennium BCE that well-organized exchange circuits started operating. These involved mainly obsidian and this raw material apparently consolidated in time, due to the role carried out by San Ciriaco and Ozieri Middle to Late Neolithic cultures in the control and development of the Monte Arci obsidian supply. Chert was never involved in these networks and was mainly exploited locally and opportunistically. However, from the end of the Neolithic, some outcrop in the Oligo-Miocene basin of Perfugas was exploited on a supra-local scale and for a relatively short period

L'obsidienne néolithique en Méditerranée occidentale

L'ossidiana è uno degli indicatori privilegiati di interazione tra le comunità neolitiche del Mediterraneo occidentale. Attraverso l'analisi diacronica dello sfruttamento delle quattro sorgenti insulari di questa materia prima presenti nella regione, seguendo un approccio che integra tecniche di caratterizzazione della provenienza ed analisi tipo-tecnologica delle industrie, vengono focalizzate le tendenze alla progressiva strutturazione di differenti reti di scambio. Attraverso questi canali si seguono i processi di cambiamento delle entità culturali e l'evoluzione nelle forme di organizzazione del sistema di produzione litica, riflesso del progressivo mutamento del valore assegnato all'ossidiana

Water quality evaluation in Mediterranean Lagoons using the Multimetric Phytoplankton Index (MPI): study cases from Sardinia

1 - Water quality in four Sardinian lagoons (western Mediterranean Sea) was assessed using the Multimetric Phytoplankton Index (MPI), which is consistent with the EU Water Framework Directive. The index was developed using data on phytoplankton abundances, species structure and chlorophyll a concentrations in Venice Lagoon, Italy. 2 - The aim of this study was to test the MPI on a larger geographical scale and across a range of lagoon types. Therefore, it was applied to assess water quality in the Cabras, S’Ena Arrubia, Santa Giusta and Calich lagoons in Sardinia. These lagoons are all “choked”, but exhibit a range of sizes and morphometric features. They are directly affected by human activity within the lagoons themselves, such as fisheries, aquaculture and the construction of dams and canals, and are indirectly affected by anthropogenic activities in their catchments, including intensive agriculture, industrial activity and urban development. 3 - The data used in the present study were collected monthly over a period of 4 years (Calich, Santa Giusta and S’Ena Arrubia) to 7 years (Cabras). Samples were collected at three stations at each of the Cabras, Santa Giusta and Calich lagoons, and at two stations at the S’Ena Arrubia Lagoon, providing a total of 220 samples. 4 - The water quality in three of the four lagoons investigated (Cabras, S’Ena Arrubia and Calich) was classified as bad using the MPI. Among these three, water in Cabras Lagoon exhibited the worst condition. Water quality in Santa Giusta Lagoon was classified as poor using the MPI. 5 - Although we present preliminary results that require further verification, the index appears to be a useful tool for assessing the ecological status of typical Mediterranean lagoons

Dominancia de las cianobacterias en lagunas mediterráneas hipertróficas: el caso de la laguna de Cabras (Cerdeña, Italia)

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 (Planktothrix sp. and Pseudanabaena catenata; Reynolds functional group S1) and late spring growth of Nostocales (Aphanizomenon gracile, Aphanizomenon aphanizomenoides, and Anabaenopsis 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.Durante dos años (julio 2007-junio 2009) se monitoreó una proliferación intensa de cianobacterias en la laguna de Cabras, así como los parámetros ambientales y climáticos que determinaron sus variaciones temporales. Durante 17 meses, Chroococcales fue el único orden de cianobacterias en la laguna, del cual células similares a Cyanobium (grupo funcional Z según Reynolds) fueron las más importantes en cuanto a abundancia. En los meses siguientes, las cianobacterias sufrieron cambios drásticos, que ocurrieron simultáneamente con lluvia constante e intensa que dio lugar a una caída brusca de la salinidad de la laguna. Se monitoreó también la sucesión de Oscillatoriales en otoño-invierno (Planktothrix sp. and Pseudanabaena catenata; grupo funcional S1 según Reynolds) y el crecimiento en primavera de Nostocales (Aphanizomenon gracile, Aphanizomenon aphanizomenoides, y Anabaenopsis circularis; grupo funcional H1 según Reynolds). Análisis de Correspondencia Canónica permitieron cuantificar la influencia de las variables ambientales, indicando una estrecha relación entre Chroococcales y salinidad, Oscillatoriales y altos niveles de SRP y proporción DIN/SRP, y Nostocales y bajos niveles de nutrientes, proporción DIN/SRP y salinidad