Sardine (Sardina pilchardus) spawning seasonality in European waters of the northeast Atlantic

Egg data from ichthyoplankton monitoring sites in the western English Channel (1988–2003) and northern Spain (1990–2000) and macroscopic maturity data from biological samples of purse seine landings in western and southern Iberia (1980–2004) are used to describe the spawning seasonality of sardine (Sardina pilchardus) in European waters of the northeast Atlantic using generalised additive models. The fitted models reveal a double peak in spawning activity during early summer and autumn in the western Channel, a wider spring peak off northern Spain and a broad winter season in the western and southern Iberian Peninsula. At all sites, a high probability of spawning activity was observed over at least 3 months of the year, with the duration of the season increasing with both decreasing latitude and increasing fish size. Off western and southern Iberia there are indications that the spawning season has been of longer duration in recent years for all size classes (reaching in some cases 8 months of the year for large fish). These patterns are in general agreement with existing literature and theoretical expectations of sardine spawning being driven locally by the seasonal cycle of water temperature, assuming preferences for spawning at 14 –15°C and avoidance for temperatures below 12°C and above 16°C. Regional quotient plots indicated that spawning tolerance to higher temperatures increases progressively with decreasing latitude. Despite the weak evidence for geographical differences in temperature tolerance that may have some genetic origin, the degree of spatio-temporal overlap in sardine-spawning activity within Atlantic European waters is unlikely to promote any reproductive isolation in that area.     

Effects of two paralytic shellfish toxin producing dinoflagellates on the pelagic harpacticoid copepod Euterpina acutifrons

The effects of two paralytic shellfish toxin (PST) producing dinoflagellates, Alexandrium minutum Halim (high and low toxin strains) and Gymnodinium catenatum Graham, on the pelagic harpacticoid copepod Euterpina acutifrons Dana were tested in a series of experiments run from October 1994 to May 1995. In small volumes (350 ml), both strains of A. minutum (300 to 350 cells ml^-1), and G. catenatum (175 cells ml^-1), strongly reduced naupliar activity (about 30 and 17% were inactive after 24 h, respectively). Activity is here defined as movement. In medium volumes (6 litre), 40% of nauplii incubated with the high toxin strain of A. minutum (1000 cells ml^-1) and 8% of nauplii incubated with cell-free filtrate of the same culture were inactive after 24 h; these values increased to 50 and 30% respectively after 3 d. In large volumes (20 litre), adult copepods incubated with A. minutum (1000 and 10000 cells ml^-1) for 5 d revealed only trace levels of PSP-toxins (paralytic shellfish poisoning) in the extracts analysed by HPLC. With both strains of A. minutum (1000 and 10000 cells ml^-1), 10 to 15% of the copepods were inactive after 1 to 2 d. It is suggested that E. acutifrons avoids feeding on the dinoflagellates after tasting a few cells, but that the dinoflagellates may exude toxins or other substances that affect the copepods. The inactivating effect of the toxic dinoflagellates on the nauplii was more rapid and stronger than on adult copepods, although strong inactivation and death were also observed in adults with time (up to 80% were inactive after 5 d of incubation with A. minutum). Still, in our experiments a considerable proportion of adult females incubated with the toxic dinoflagellates remained active and were able to produce viable eggs for several days.     

One-year study of the elemental composition and source apportionment of PM10 aerosols in Florence, Italy

An extensive investigation was carried out for the characterisation of the air particulate composition in Florence. The aim was to determine the aerosol elemental concentrations, as well as to identify pollution sources. For our investigation, the external Particle-Induced X-Ray Emission-Particle-Induced gamma-Ray Emission beam facility of the Istituto Nazionale di Fisica Nucleare, Van de Graaff accelerator at the Physics Department of the Florence University was used. We report the results of the analysis of a long temporal series (approximately 1 yr) of PM10 particulate samples, collected on Millipore filters on a daily basis in three different sites (characterised by different urban settings). Daily concentrations of more than 20 elements were detected. The long sampling period (approximately 1 yr) allowed a comparison with the air quality recommended values and the identification of seasonal variations. Four main sources (traffic, oil-combustion, soil-dust, and wind transported sea-salt) were extracted with the help of Principal Component Analysis (PCA). An absolute PCA showed traffic to be the major source both in the high traffic site and in the urban background site.     

Background metal levels determination in bivalves – quality assessment of the European Water Framework Directive

Background levels of metals (Ag, Cd, Cu, Cr, Hg, Ni, Pb and Zn) in biomonitors (Mytilus galloprovincialis mussels and Crassostrea gigas oysters), in estuarine waters within the Basque Country (south-east Bay of Biscay) are estimated using non-parametric statistical tools and data are presented graphically, with the aim of being used in assessing the ecological status, within the European Water Framework Directive (WFD). The basis for this study was the statistical analysis of data compiled from monitoring programmes undertaken along the Basque coast, between 1990 and 2008. For this analysis, a heuristic method was adapted and used. Results showed different metal background ranges throughout the year for both mussels and oysters. Values corresponding to the upper limit of the background range (i.e. value of the upper whisker of the box-plot) are proposed as the ‘high/good’ status boundary, according to the WFD.     

A dry deposition scheme for particulate matter coupled with a well-known Lagrangian Stochastic model for pollutant dispersion

Environmental Fluid Mechanics - A 3D dry deposition scheme for particulate matter (PM) is presented as a Free-Libre and Open-Source Software (FOSS) library, DePaSITIA (RSE SpA). This combines some...     

RETRACTED ARTICLE: Perspectives for the long-term penetration of new renewables in complex energy systems: the Italian scenario

Renewable energy sources are mainly used in the electrical sector. Electricity is not a storable commodity. Hence, it is necessary to produce the requested quantity and distribute it through the system in such a way as to ensure that electricity supply and demand are always evenly balanced. This constraint is actually the main problem related to the penetration of new renewables (wind and photovoltaic power) in the context of complex energy systems. The paper analyzes some aspects in connection with the problem of new renewable energy penetration. The case of Italian scenario is considered as a meaningful reference due to the characteristic size and the complexity of the same. The various energy scenarios are evaluated with the aid of a multipurpose software taking into account the interconnections between the different energetic uses. In particular, it is shown how the penetration of new renewable energies is limited at an upper level by technological considerations and it will be more sustainable if an integration of the various energy use (thermal, mobility and electrical) field will be considered.     

Biology of the upper-slope cephalopod<Emphasis Type="Italic"> Octopus salutii</Emphasis> from the western Mediterranean Sea

A total of 310 individuals (124 males, 185 females, 1 indeterminate) of the octopod Octopus salutii caught throughout the year by bottom trawlers from 25 to 800 m depth in the western Mediterranean were analysed to study some general aspects of its biology. Octopus sizes ranged from 4.0 to 13.0 cm ML and 3.5 to 16.5 cm ML in males and females, respectively. The species inhabits the lower continental shelf and upper slope, primarily between 250 and 500 m depth. The scarcity of small-sized individuals in the samples and the predominance of males and females >8 and >9 cm ML, respectively, suggest two interpretations: (1) juveniles inhabit grounds inaccessible to, or unsampled by, trawlers, or they avoid capture owing to behavioural aspects; or (2) the species meet in the trawling grounds for reproduction, because in the sizes described the majority of individuals have begun sexual maturation. The reproductive period was found to occur during spring and summer. The stomach content analysis revealed a diet composed of 33 different prey items belonging to three major taxonomic groups (crustaceans, fishes and cephalopods). Quantitatively, crustaceans (Decapoda Reptantia and Natantia groups) were the most important prey, appearing in 87% of the stomachs, followed by fish (25%) and cephalopods (10%). Finally, the paper presents data on mantle length–total weight, gonad weight–total weight and ligulae length–total weight relationships, and utilises different indexes (gonadosomatic, hepatosomatic, fullness weight and emptiness) to describe changes through the three maturity stages of both sexes.Communicated by S.A. Poulet, Roscoff     

Heavy metals in the Sea-Skater Halobates robustus from the Galápagos Islands: Concentrations in nature and uptake experiments,with special reference to cadmium

Samples of Halobates robustus Barber (Heteroptera: Gerridae) from the Galápagos Islands were analysed by optical emission spectrometry. The levels (in g g^-1 dry weight) of Zn (134), Cu (155), Pb (< 1), Cd (7), and Cr (3) were not significantly different among insects of different sexes or developmental stages. The low natural levels of Cd in H. robustus from the relatively unpolluted environment of the Galápagos Islands are compared to the high concentrations of Cd in Halobates spp. from relatively polluted regions. Since the measured levels of Cd in their natural zooplankton food rarely exceed 10 g g^-1, and very little of the Cd is found in the soft tissues, the high Cd concentrations (100 to 200 g g^–1) in some seaskater species have evidently been derived by drinking from the surface microlayer of the seawater.     

Allelopathy,a chance for sustainable weed management

The exploitation of crop allelopathy against weeds may be useful to reduce issues related to the use of herbicides. Several crops, such as alfalfa, barley, black mustard, buckwheat, rice, sorghum, sunflower and wheat, demonstrate strong weed suppression ability, either by exuding allelochemical compounds from living plant parts or from decomposing residues. As well as the positive effect on weed reduction, the introduction in agronomic rotations of allelopathic crops, their use as a mulch to smother crops or as a green manure may also be helpful in reduction of other agricultural problems, such as environmental pollution, use of unsafe products and human health concerns, through a reduction in chemical inputs. Knowledge of allelopathic properties of crops may also be advantageous in mitigation of soil sickness. Moreover, information on weed allelopathy may be profitable in preventing serious crop damage if the weed biomass is buried in the soil, and a crop susceptible to allellochemicals is planned for the following year. The use of allelopathic traits from crops or cultivars with important weed inhibition qualities, together with common weed control strategies, can play an important role in the establishment of sustainable agriculture.