Assessment of the state of agroecosystem sustainability using landscape indicators: a comparative study of three rural areas in Greece

The research was based on a comparative study of three representative rural areas (Dovras, Larissa, and Messapia) in Greece. Remote sensing data were collected (maps, aerial photographs) for the landscape analysis and elaborated using GIS linked with economic and social parameters regarding land use. By using a selected core set of landscape indicators, this research aims at providing a useful tool for assessing agroecosystem management at territorial level and hopefully assist decision-making for the promotion of sustainability. The selected tool showed that the study area of Messapia presented the highest level of environmental sustainability, while the area of Dovras showed the best combination of agricultural productivity and landscape management. Results showed that the ecoregions of Dovras, Larissa, and Messapia presented a landscape composed of important ecological function areas in the percentages of 40%, 15%, and 70%, respectively, and of cultivated areas in the percentages of 55%, 71.19%, and 19.75%, respectively.     

Azo-dyes photocatalytic degradation in aqueous suspension of TiO2 under solar irradiation

The photodegradation of two common and very stable azo-dyes, i.e. methyl-orange (C₁₄H₁₄N₃SO₃Na) and orange II (C₁₆H₁₁N₂SO₄Na), is reported. The photocatalytic oxidation was carried out in aqueous suspensions of polycrystalline TiO₂ irradiated by sunlight. Compound parabolic collectors, installed at the “Plataforma Solar de Almería” (PSA, Spain) were used as the photoreactors and two identical reacting systems allowed to perform photoreactivity runs for the two dyes at the same time and under the same irradiation conditions. The disappearance of colour and substrates together with the abatement of total organic carbon content was monitored. The main sulfonate-containing intermediates were found to be in lower number in respect to those obtained under artificial irradiation. In particular there were no more evidence of the presence of hydroxylated transients. The dependence of dye photooxidation rate on: (i) substrate concentration; (ii) catalyst amount; and (iii) initial pH was investigated. The influence of the presence of strong oxidant species (H₂O₂, S₂O₈²⁻) and some ions (Cl⁻, SO₄²⁻) on the process was also studied.     

Sensitive Parameters In Predicting Exposure Contaminants Concentration In A Risk Assessment Process

A sensitivity analysis (SA) was conducted on the analytical models considered in the risk-based corrective-action (RBCA) methodology of risk analysis, as developed by the American Society for Testing of Materials (ASTM), to predict a contaminant‘s concentration in the affected medium at the point of human exposure. These models are of interest because evaluations regarding the best approach to contaminated site remediation are shifting toward increased use of risk-based decision, and the ASTM RBCA methodology represents the most effective and internationally widely used standardized guide for risk assessment process. This paper identifies key physical and chemical parameters that need additional precision and accuracy consideration in order to reduce uncertainty in models prediction, thereby saving time, money and engineering effort in the data collection process. SA was performed applying a variance-based method to organic contaminants migration models with reference to soil-to-groundwater leaching ingestion exposure scenario. Results indicate that model output strongly depends on the organic-carbon partition coefficient, organic-carbon content, net infiltration, Darcy velocity, source-receptor distance, and first-order decay constant.     

Can a marine pest reduce the nutritional value of Mediterranean fish flesh?

Biological invasions are deemed as one of the most severe threats to biodiversity and can result in huge economic impacts on natural resources. Many studies have assessed structural changes caused by the introduction of nonindigenous species, but urgent questions remain to be answered about the complex indirect effects of invasive pests on marine biodiversity at the species and ecosystem level. Previous investigations focusing on the biological invasion by Caulerpa racemosa in the Mediterranean indicated that the lipophilic algal metabolite caulerpin accumulates in the tissues of the native edible white sea bream Diplodus sargus feeding on the exotic alga. The level of caulerpin in D. sargus has been thus used as an indicator of the trophic exposure of the fish to the seaweed and related with adverse effects on the fish health. In the present study, we show that the C. racemosa-based diet can also alter muscle fatty acids composition in the white sea bream by reducing the percentage of polyunsaturated fatty acids of the n-3 and n-6 series, such as eicosapentaenoic (C20:5), docosahexaenoic (C22:6) and arachidonic acids (C20:4). This represents both a real threat to the health of fish unable to biosynthesize these essential fatty acids and an impoverishment of an important source of essential fatty acids for human nutrition, which helps to prevent cardiovascular diseases, diabetes, hepatic steatosis, cancer and neurological disorders. On the whole, this work sheds light on an unexplored and critical aspect of biological invasions with implication on the health of both humans and the environment.     

Floater mortality within settlement areas can explain the Allee effect in breeding populations

The Allee effect (the positive relationship between population growth rate and population size) is a constraint of some animal populations at low numbers, which increases their likelihood of extinction because of a decrease in reproduction and/or survival. We were able to demonstrate that the Allee effect can be the result of a mortality increase affecting floaters (i.e. dispersing individuals able to enter as breeders in the reproductive population when a breeding territory or a potential mate – owner of a suitable breeding territory – becomes available). Previously, potential mechanisms underlying Allee effects were always related to the breeding portion of a population only. In contrast, our understanding of or solutions to population declines due to the Allee effects can reside elsewhere, away from breeding territories.     

Life style and genetic variation in teleosts: the case of pelagic (<Emphasis Type="Italic">Aphia minuta</Emphasis>) and benthic (<Emphasis Type="Italic">Gobius niger</Emphasis>) gobies (Perciformes: Gobiidae)

The pattern of genetic variability of two species of Mediterranean gobiids was compared, with reference to their different life history traits (Aphia minuta paedomorphic and pelagic; Gobius niger metamorphosed and benthic). The aim was to evaluate how different life histories can affect the genetic structure in these marine teleosts. The study was carried out on populations of both species sampled in the western Mediterranean and in the Adriatic Sea. Seven restriction endonucleases were used for the RFLP analysis of a mitochondrial DNA segment comprising the NADH dehydrogenase subunits 3, 4L and 4. The results highlighted two different patterns of genetic variation, a weak genetic structure in A. minuta and population subdivision in G. niger. These observations may be explained not only in terms of the different dispersal capabilities of these species, but also considering that A. minuta is an abbreviate iteroparous spawner while G. niger is a protracted iteroparous spawner. Because abbreviate iteroparity is a reproductive strategy selected in stable environments with high resource availability, Pliocene and Pleistocene climate oscillations may have represented factors that negatively influenced the reproductive success of A. minuta, producing demographic fluctuations and bottlenecks, as suggested by the mismatch distribution analysis. The weak genetic structure of A. minuta populations seems to be therefore due to a more recent re-colonization of the Mediterranean basin after a severe population decline, rather than to the high vagility of this pelagic goby.     

A numerical (LES) investigation of a shallow-water, mid-latitude, tidally-driven boundary layer

We investigate turbulent mixing in a tidally driven, mid-latitude, shallow-water basin. The study is carried out numerically at a laboratory-scale, using large-eddy simulation. We compared the results of the simulation with those of a correspondent purely oscillatory flow (Stokes boundary layer). The effect of rotation on the flow dynamics is twofold. First, rotation gives rise to a mean spanwise flow that concurs to redistribute the turbulent energy among the Reynolds stresses, in particular between the horizontal directions, thus increasing the mixing across the water column and thickening the layer where developed turbulence is observable. Second, the presence of the horizontal component of the background vorticity (latitude effect) breaks the symmetry between the two semi-cycles of the oscillation, since turbulence results suppressed/enhanced during the first/second semi-cycle. These two effects significantly modify the turbulent characteristics with respect to the purely oscillating flow, although the mechanisms that generates turbulence present similar features. The qualitative agreement between our results and some measurements carried out in two sites with characteristics similar to the case analyzed suggests that the outcomes here provided may be of general use for the analysis of mid-latitude, neutrally stratified, shallow-water basins mainly driven by semi-diurnal tidal currents.     

Relationship between arsenic accumulation in tissues and hematological parameters in mullet caught in Faro Lake: a preliminary study

The authors investigated the arsenic (As) accumulation in different tissues (muscle, gill, liver, stomach, and intestine) and the possible correlation between tissue concentration and hematological parameters in mullet (Mugil cephalus Linnaeus, 1758) caught in Faro Lake (Messina, Sicily, Italy). On all fish, hematological analyses of blood samples, measurement of biometric indices, and the removal of the muscles, gills, liver, stomach, and intestine for the determination of arsenic concentration were performed. A hemogram was performed to find effects of arsenic concentration in tissues on hematological variables. One-way analysis of variance showed significant differences of arsenic concentration in different tissues, with higher values in the gill. The correlation between hematological parameters and tissue arsenic concentration showed a statistical significance for red blood cell (RBC), hemoglobin concentration (Hb), and hematocrit (Hct) with the liver As concentration. Biometric indices (weight, length, and fork length) showed a significant correlation with As concentration of the muscle and liver also. Our results indicate the role of some hematological parameters as biomarkers useful to monitoring anthropogenic load of arsenic in water and sediment, because variations of these parameters represent one of the effects that arsenic exposure can have on fish.