Northeast Sardinia Research Articles

Adaptive Response to Gillnets Bycatch in a North Sardinia Mediterranean Shag (Gulosus aristotelis desmarestii) Population.

Mediterranean Shag (Gulosus aristotelis desmarestii) is a seabird endemic to the Mediterranean and Black Seas, recently included in the IUCN list of threatened Species. Most of the reproductive colonies are hosted in Sardinia and surrounding islets. Bycatch in fishing nets is one of the most significant threats for this population. Our work aimed to assess alterations in the sex ratio caused by bycatch and to study the adaptive response of the population to a skewed adult sex ratio. The sex ratio of Mediterranean Shags found drowned in the gillnets near the colonies and that of the nestlings of the Corcelli (northeast Sardinia) colony was determined using the sex-linked polymorphism of the gene Chromobox-Helicase-DNA-binding 1. The data of the shags found drowned in gillnets evidenced a high mortality rate (83.3%; p < 0.001) and a larger size of males (35% heavier than females, p < 0.05) compared to females, supporting the theory that heavier individuals are able to forage at great depths. With 64.8% of the nestlings being male, the sex ratio of nestlings was statistically different from parity (p < 0.05). Furthermore, it was related to the brood size. In one- and two-chick broods, 73% and 70% of nestlings, respectively, were males, while in three-chick broods, only 33% were males. Our data identify the higher rate of male shags drowned in gillnets as a factor causing an alteration of the sex ratio in the Mediterranean Shag population. According to the Sex Allocation Theory, an adaptive adjustment of sex made by adult females restores the Mendelian sex ratio in the population.

Circular economy in marble industry: From stone scraps to sustainable water-based paints

Huge amounts of sludge waste are produced every day during the sawing and processing of carbonate ornamental stones. Most of these materials are landfilled and create serious environmental and health hazards. Thus, it is mandatory to find alternative solutions to recycle them. Since calcium carbonate is the most widely used mineral filler for interior and exterior emulsion paints, this investigation focused on the feasibility of trying out innovative methods of circular economy in a waste processing area. Focusing in the Orosei Marbles’ producing area (North-East Sardinia, Italy), the aim of this study was to compare the performance of water-based paints, through the use of marble sludge waste, as mineral fillers, rather than commercial CaCO3. According to standard normative tests were carried out on paint samples, prepared according to an experimental formulation, after a preliminary chemical and physical characterization of the fillers. The results indicate that the marble sludge waste can be successfully used as mineral filler in water-based paints, and that it requires only light pre-treatments consisting of deagglomeration and mechanical dispersion in a wet medium, thus confirming its environmental and economic benefits.

First characterization of a Bronze Age textile fibre from Sardinia (Italy)

This paper describes a case study of a linen yarn found inside a spiral bronze necklace fragment during an excavation campaign in la Prisgiona, a Nuragic settlement, near Arzachena, in north-east Sardinia. The site is one of the most interesting settlements of the Nuragic period. Abandoned after a fire, it was no longer inhabited, thus allowing the preservation of the Nuragic stratigraphy. The necklace fragments are part of a votive burial and the yarn is the only known textile material belonging to the Bronze Age period from Sardinia. The uniqueness of the finding, in the rare corpus of prehistoric textile materials, and the small amount of it available do not allow conventional analyses and requires a non-invasive/micro-invasive method. The protocol established to preserve as much as possible the entirety of the object, involving polarize light microscopy, portable ATR-FTIR, SEM-EDS, micro X-ray Computer Tomography and XRD, was successfully used to extend knowledge about the materials and techniques of this civilisation.

Neutron-based techniques for archaeometry: characterization of a Sardinian boat model

Sardinian metallurgy produced samples of high artistic and historical value. In particular, ship models are rare and unmatched examples of the mastery reached by Sardinian metallurgists and their production process deserves an in-depth analysis of all the phases involved in the making. In this work, we examined a Sardinian boat model to obtain information about its composition, microstructure and manufacturing technique. The object is a small bronze ship model that was found near the Nuraghe Colovros, located in north-east Sardinia (Italy). It was analysed by means of neutron imaging and neutron diffraction experiments at the ISIS Pulsed Neutron and Muon Source laboratory (Harwell, UK). Neutron techniques are relatively new in the field of archaeometry, but they are a very effective tool for the study of archaeological objects: they permit to survey complete artefacts, determine compositions and structures, assess the conservation status and address questions of effective use and casting techniques. This type of data can add new and different insights to existing archaeological information, especially where sampling is not permitted. The outcome of the study reveals a peculiar approach to the manufacturing of the boat model.

Multilayer corona textures in the high-pressure ultrabasic amphibolite of Mt. Nieddu, NE Sardinia (Italy): equilibrium versus disequilibrium

Rocks with coronitic textures around igneous relics of olivine and plagioclase were sampled from the ultramafic amphibolite of Mt. Nieddu being part of the so-called Migmatite Complex of northeast Sardinia. These textures are characterized by mono- or bi-mineralic layers of orthopyroxene and clinopyroxene around olivine, and a symplectite of clinopyroxene + spinel and garnet around plagioclase; all these minerals were overgrown by amphibole. We applied conventional geothermobarometry and P-T pseudosection modelling of microdomains in order to constrain the main steps of the evolution of the sampled rocks. The igneous crystallization occurred at 0.2-0.5 GPa and minimum T of 780-850 °C. Garnet is the last coronitic phase formed at estimated pressures of 1.3-1.7 GPa at 680-730 °C. As similar conditions were previously determined for the pressure peak on an adjacent rock, we conclude that during corona formation chemical equilibrium was reached probably over a much wider range than of mm-sized microdomains. Slow reaction kinetics is responsible for the partial preservation of the igneous phases.

Chemical composition and in vitro bioactivity of essential oil obtained from the flavedo of ‘Pompia’, an ancient Sardinian fruit

ABSTRACTPompia (Citrus limon var. pompia) grows in the North-East Sardinia (Italy). This fruit is used in traditional pastries, the flavedo for the preparation of liqueurs by hydroalcoholic infusion. We investigated the chemical composition and bioactivity of the essential oil obtained by hydro-distillation from the peel of pompia (PEO). Gas chromatographic analysis allowed us to determine the PEO chemical composition: the major compound was limonene (LM) (803.8 mg/mL). PEO showed antioxidant activity in the β-carotene/linoleic acid bleaching test and radical-scavenging activity in the DPPH assay. PEO significantly reduced viability in HeLa and B16F10 cancer cells, and its toxic effect was mainly associated with LM cytotoxicity. PEO significantly increased intracellular free radical levels in cancer cells, without affecting the cellular phospholipid composition. The HPLC-DAD analysis of the cancer cell medium after PEO-treatment revealed the presence of perillic acid, a LM metabolite with anticancer activity. Our findings provide new insights for the PEO nutraceutical potential.

The crisis of granite and the success of marble: errors and market strategies. The Sardinian case

Since the beginning of the sixties, Sardinia (Italy) has established itself as a granite production area both nationally and internationally. The activity of quarrying and processing of marble began in the Orosei area (north-east Sardinia) by the end of the same decade. This study is aimed at describing the troubled time experienced by the Sardinian granite production at the beginning of the XXI century and the ongoing success achieved by Orosei marble. In fact, what was originally a less developed segment, the marble sector, became more established on the international market thanks to a number of optimal marketing strategies. The weaknesses and strengths of these two different sectors are described below. The paper gives an account of the current positioning strategies of stone industry in Sardinia with special attention to commercial development, the positioning of the product portfolio, quality and customer service. Although the Sardinian granite is a raw material with excellent features which are typical of commodities and is supported by the presence of skilled manpower, this industry has always had to deal with the high costs of the transport system and the lack of efficient infrastructure, until the Chinese competition gave it the final push. In contrast to the granite industry, the marble entrepreneurs of Orosei showed better marketing skills. The Sardinian marble industry has the strategic advantage of having all companies concentrated in a limited and homogeneous area of quarrying and processing activities. Furthermore, producers together with the Municipality of Orosei founded a Consortium whose aim is currently to manage waste disposal at the landfill with the idea of transforming the landfill itself into a Centre for stone materials aimed at secondary processing, where training sessions on different subjects pertaining to the Dimension Stone sector will be held and a historical route aimed at industrial tourism will be organized.

Diversity of Phytophthora Species from Declining Mediterranean Maquis Vegetation, including Two New Species, Phytophthora crassamura and P. ornamentata sp. nov.

The Mediterranean basin is recognized as a global biodiversity hotspot accounting for more than 25,000 plant species that represent almost 10% of the world’s vascular flora. In particular, the maquis vegetation on Mediterranean islands and archipelagos constitutes an important resource of the Mediterranean plant diversity due to its high rate of endemism. Since 2009, a severe and widespread dieback and mortality of Quercus ilex trees and several other plant species of the Mediterranean maquis has been observed in the National Park of La Maddalena archipelago (northeast Sardinia, Italy). Infected plants showed severe decline symptoms and a significant reduction of natural regeneration. First studies revealed the involvement of the highly invasive wide-host range pathogen Phytophthora cinnamomi and several fungal pathogens. Subsequent detailed research led to a better understanding of these epidemics showing that multiple Phytophthora spp. were involved, some of them unknown to science. In total, nine Phytophthora species were isolated from rhizosphere soil samples collected from around symptomatic trees and shrubs including Asparagus albus, Cistus sp., Juniperus phoenicea, J. oxycedrus, Pistacia lentiscus and Rhamnus alaternus. Based on morphological characters, growth-temperature relations and sequence analysis of the ITS and cox1 gene regions, the isolates were identified as Phytophthora asparagi, P. bilorbang, P. cinnamomi, P. cryptogea, P. gonapodyides, P. melonis, P. syringae and two new Clade 6 taxa which are here described as P. crassamura sp. nov. and P. ornamentata sp. nov. Pathogenicity tests supported their possible involvement in the severe decline that is currently threatening the Mediterranean maquis vegetation in the La Maddalena archipelago.

Application of CarboSOIL model to predict the effects of climate change on soil organic carbon stocks in agro-silvo-pastoral Mediterranean management systems

CarboSOIL model and climate outputs from two GCMs (GISS and HadCM3), three time horizons (2020, 2050, 2080), and two emission scenarios (A2 and B2) according to IPCC were used to study the effects of climate change on soil organic carbon (SOC) stocks in a Mediterranean region (Northeast Sardinia, Italy). CarboSOIL is an empirical model based on regression techniques and developed to predict SOC contents at standard soil depths of 0–25, 25–50 and 50–75cm. The area is characterized by extensive agro-silvo-pastoral systems, and six land uses with different levels of cropping intensification were compared: tilled vineyards (TV), no-tilled grassed vineyards (GV), hay crop (HC), pasture (PA), cork oak forest (CO), and semi-natural systems (SN). The main objectives were: (i) to validate the model predictions with the measured SOC stocks, and (ii) to predict SOC stocks in future climate projections for the different land use types.The model proved its ability to predict SOC stocks at different soil depths, and can be used as a tool for predicting SOC stocks under different climate change scenarios.The results suggest that future climatic scenarios can have a negative effect on SOC stocks in the upper sections of the soil profile, mainly due to a very low increase in the 0–25cm section and a sharp decrease in the 25–50cm soil section, in particular in a long term perspective (2080) and under the emission scenario A2.Important decreases of SOC stocks were found in the upper soil sections of the vineyards.

Human trampling effects on Mediterranean coastal dune plants

Coastal habitats are particularly vulnerable to recreational impacts because these environments are highly dynamic and continually change in response to biotic and abiotic factors. Sand dune communities are worldwide characterized by high levels of biodiversity, but are often affected by human-induced impacts as those caused by tourist trampling. To understand the effects of human frequentation, trampling, and other human-induced impacts, fencing experiments have been traditionally carried out on coastal dunes. Since in touristic areas dune systems are subjected to different intensities of human frequentations rather than to opening or fencing, in this study we explore the effects of accessibility on vascular plants cover. This study tests the hypothesis that human frequentation on beaches affects spatio-temporal variability of vascular plant abundance on dunes by comparing the plant assemblages of high and low accessible sites in North-East Sardinia (Italy). Our results show that accessibility plays a crucial role in conditioning the percentage of vegetation cover in Mediterranean dunes. In fact, not only we found a perennial vegetation cover that was significantly higher in the sites with low accessibility (and consequently low frequentation), but we also showed that at the sites with high accessibility there were significant differences in vegetation cover between times of sampling (cover was higher before than after summer): on the contrary, differences in perennial vegetation cover among times were not significant at the low frequentation sites. After summer, the difference among low and high frequentation sites in species composition and cover was >90%. Multivariate analysis identified those species that play a pivotal role in differentiating the low and the high frequentation sites. Among them, Crucianella maritima and Sporobolus virginicus can be considered as differential species. Overall, our data show vegetation and plant species responses to human-induced impacts, and are therefore important to support conservation actions in Mediterranean coastal areas interested by mass tourism.

Geothermobarometry on anatectic melts – a high-pressure Variscan migmatite from northeast Sardinia

We studied a high-pressure amphibole-bearing migmatite cropping out along the northeastern coast of Sardinia, a few kilometres northeast of Olbia, in order to improve our knowledge about its evolution using pressure–temperature (P–T) pseudosections. Thermodynamic calculations with PERPLE_X were undertaken in the system Na2O–K2O–CaO–FeO–MnO–MgO–Al2O3–TiO2–SiO2–H2O using a haplogranitic melt model. Calculations were conducted for average compositions of the protolith and the tonalitic leucosome with different contents of H2O to construct various pseudosections in the P–T range 2–20 kbar and 550–900°C. We demonstrate that the molar ratios Na/K and Si/Al of the anatectic melt are of high geothermobarometric value. Particularly the melt field in the P–T pseudosection for the protolith, contoured by Si/Al isolines, shows a significant decrease in this ratio with rising pressure. This ratio is only weakly dependent on variable H2O contents of the amphibole-bearing migmatite as demonstrated by contoured T–H2O pseudosections. The application of the Na/K and Si/Al ratios in melt yielded P–T conditions close to 13 kbar and 700°C, assigned as the conditions of partial melting. Evaluation of contoured P–T pseudosections for the leucosome composition resulted in conditions of about 10.5 kbar and 700°C for the crystallization of amphibole in the leucosome melt, and 9 kbar and 680°C for complete crystallization of this melt.

Protection effects on Mediterranean fish assemblages associated with different rocky habitats

Rocky banks (i.e. sea mountain-like structures rising from the sea bottom) are hard substrate habitats of high socio-economic value (e.g. for fishermen and divers) and ecological relevance as they often host unusually high density of fish. Here we tested whether the response of fish assemblages to protection (i.e. related to the presence of a Marine Protected Area (MPA)) in rocky banks is comparable with the response of rocky reefs dropping from the coast (hereafter called ‘coastal rocky substrates’), and whether there are differences between fish assemblages associated with protected and unprotected rocky banks. Fish assemblages were assessed in shallow and deep coastal rocky substrates, and in rocky banks, in unprotected and protected conditions at a Mediterranean MPA in north-east Sardinia in August 2007 and 2008. Whole fish assemblage structures (in terms of biomass) differed between protected and unprotected conditions in both study years. Fish assemblages at rocky banks, in addition, differed from those associated with coastal rocky substrates. Total fish biomass (summing contribution of all species) was higher under protected than unprotected condition in 2007, while species richness and total fish density did not demonstrate any significant change related to protection. The responses to protection displayed by the target species Epinephelus marginatus and Diplodus sargus were clear especially in terms of greater frequency of large-sized specimens in both study years. Biomass of E. marginatus in 2007 and density of D. sargus in 2007 and 2008 were significantly higher in protected than unprotected conditions, especially in protected rocky banks. This study emphasizes the ecological and socio-economic role of protection and the potential role of rocky banks within management/conservation programmes in the Mediterranean Sea.

Dissecting the genetic make-up of North-East Sardinia using a large set of haploid and autosomal markers

Sardinia has been used for genetic studies because of its historical isolation, genetic homogeneity and increased prevalence of certain rare diseases. Controversy remains concerning the genetic substructure and the extent of genetic homogeneity, which has implications for the design of genome-wide association studies (GWAS). We revisited this issue by examining the genetic make-up of a sample from North-East Sardinia using a dense set of autosomal, Y chromosome and mitochondrial markers to assess the potential of the sample for GWAS and fine mapping studies. We genotyped individuals for 500K single-nucleotide polymorphisms, Y chromosome markers and sequenced the mitochondrial hypervariable (HVI-HVII) regions. We identified major haplogroups and compared these with other populations. We estimated linkage disequilibrium (LD) and haplotype diversity across autosomal markers, and compared these with other populations. Our results show that within Sardinia there is no major population substructure and thus it can be considered a genetically homogenous population. We did not find substantial differences in the extent of LD in Sardinians compared with other populations. However, we showed that at least 9% of genomic regions in Sardinians differed in LD structure, which is helpful for identifying functional variants using fine mapping. We concluded that Sardinia is a powerful setting for genetic studies including GWAS and other mapping approaches.

Genetic variability in the Sardinian population of the manila clam, Ruditapes philippinarum

Abstract The genetic variability of microsatellites was investigated among allochthonous populations of Ruditapes philippinarum (Bivalvia, Veneridae) at six sites in the Gulf of Olbia (North-East Sardinia) and one site in the Lagoon of Sacca di Goro (North Adriatic Sea). Our results demonstrate the lack of genetic substructuring of R. philippinarum populations within the Gulf of Olbia. Furthermore, we found highly similar estimates of within-population genetic variability without evidence of genetic differentiation between Sardinian and Adriatic populations. The lack of a signature of a founder effect in the Sardinian samples, notwithstanding their recent introduction, indicates that the number of R. philippinarum individuals released into the Gulf of Olbia may have been high enough to reduce the loss of genetic variability due to genetic drift. Furthermore, the absence of genetic differentiation observed between samples from the two areas suggests that the two populations belong to the same gene pool. Our results also indicated that R. philippinarum is rapidly colonizing the Gulf of Olbia and the neighboring areas, which is likely favored by its high potential for dispersal.

Evaluating the effects of protection on two benthic habitats at Tavolara-Punta Coda Cavallo MPA (North-East Sardinia, Italy)

In this paper, two benthic habitats have been investigated in a fully protected site and two control sites at the Tavolara-Punta Coda Cavallo marine protected area (MPA) (NE Sardinia). Overall, a protection effect on the benthic assemblages was highlighted in the shallow subtidal (5 m deep) rather than at intertidal algal turf habitat. Structure of assemblages at the shallow subtidal habitat is different in the fully protected site vs. controls, while this was not true for the intertidal habitat. At the subtidal, this finding is probably linked to indirect effects due to an increase of consumers in the protected site (e.g., sea urchins), while the lack of direct impacts in the intertidal at control sites is indicative of very similar assemblages. Cover of encrusting algae was significantly higher at the subtidal protected site suggesting a possible higher grazing pressure. Possible causes underlying the inconsistency of results obtained between habitats include the possibility that trophic cascade effects have a different influence at different heights on the shore. The need to estimate the interconnection among benthic habitats through trophic links is also highlighted to provide an estimate of the vulnerability to protection of various habitats.

Management problems in Mediterranean cork oak forests: post-fire recovery

The objective of this paper is to present the results of a long-term research project carried out in north-east Sardinia, which aims to evaluate the effects of three different kinds of forest management (traditional trunk coppicing, branch pruning, and no sylvicultural practice) on the post-fire recovery of a cork oak ( Quercus suber L.) stand. The most and the least effective forestry operations appeared to be traditional trunk coppicing and the branch pruning, respectively. Where traditional trunk coppicing is considered strictly necessary, the opportunity of thinning some of the new suckers should be carefully considered, as modern harvesting techniques should be combined with appropriate strategies to protect the soil from erosion.

The role of occupation and a past history of malaria in the etiology of classic Kaposi's sarcoma: a case-control study in north-east Sardinia.

A case-control study was performed to determine the role of rural factors including occupation and previous malaria exposure in the development of classic Kaposi's sarcoma (CKS) in a high incidence area of Europe. The occurrence of CKS association with other malignancies was also examined. The results showed that the risk of having CKS was significantly increased in subjects farming cereals, while a previous history of malaria did not influence the risk of developing CKS. A near-significant increase in associated tumours was found.

The phytoplankton of the internal Gulf of Olbia (North-East Sardinia) between July 1992 and July 1993

Abstract The density variations and phytoplankton structure of the internal Gulf of Olbia (north-east Sardinia) from July 1992 to July 1993 are described. The most important class was the Bacillariophyceae, because it accounted for the maximum values and because it dominated over about one-third of the study cycle. The picoplankton was present practically all the year round with the greatest development from September to March. Prymnesiophyceae, Dinophyceae, Cyanophyceae and Euglenophyceae were found more numerously in summer and autumn 1992 than in the rest of the year, while Bacillariophyceae, Chlorophyceae and Chrysophyceae were mostly found in spring and summer 1993. Among the 16 species that expressed the highest mean yearly density values (greater than 1×104 cell I-1), 10 were Bacillariophyceae, 2 Dinophyceae, 3 Chrysophyceae and 1 Chlorophycea. The Bacillariophyceae have also been the dominant class in floristic terms (49 taxa on 95 total), followed by the Dinophyceae (26), the Chlorophyceae (5), the Chrysophyceae (5), the Prymnesiophyceae (4), the Prasinophyceae (2), the Euglenophyceae (2) and the Cyanophyceae (2).

Geophysical interpretation of the Gallura magnetic anomaly (northeast Sardinia, Italy)

Abstract The metamorphic basement of northeastern Sardinia is mostly formed of migmatitic gneisses and exhibits Variscan granitic rocks characterized by a temporal differentiation evolving from a quite high content of Fe-Mg to an Fe-Mg-poor member. This area is also characterized by the largest magnetic anomaly in Sardinia, which has been interpreted by means of Euler and Werner deconvolution techniques and modelled 2D and 2.5D. In order to estimate the magnetic effect of the topographic irregularities, samples of the most frequently outcropping rocks were collected and magnetic remanences and susceptibilities determined in the laboratory. The effect of the topographic irregularities was computed in 2D. This effect is around twenty times smaller than the observed anomaly and therefore the observed anomaly cannot be attributed to the topographic relief. The results of the deconvolutions were used to constraint the depth and horizontal locations of the magnetic sources for the 2D and 2.5D modelling. A purely geophysical model is presented, but some geological hypotheses that accord with the geophysical interpretation are proposed and briefly discussed.

New data on the earthworm fauna of Gallura (northeast Sardinia)

From a previous analysis of the earthworm fauna of the Sardo-Corsican system, Gallura (northeast Sardinia) seemed to harbour a small number of species (7), mostly endemic and quite different from those of the neighbouring districts, even of the nearest smaller islands forming the Maddalena archipelago. During 1988–1989 over 400 specimens were collected in 19 new localities. The new data doubles the number of species known for the region, but confirms the high degree of endemicity of its fauna, which may be explained in the light of historical and ecological factors. Dendrobaena cognettii gallurensis n. ssp is described.