Sperm removal and ejaculate size correlate with chelae asymmetry in a freshwater crayfish species

Asymmetry in traits of sexual relevance may impair copulation behaviour and sexual performance of males, ultimately resulting in a fitness cost. Freshwater crayfish males use chelae, a sexually selected trait, to secure and position the female prior to and during mating. Thus, a relatively large chelae asymmetry, resulting from accidental loss and regeneration of one cheliped after autotomy, could have great consequences for male sexual behaviour. We studied copulatory behaviour and sperm expenditure of males paired to a mated female in Austropotamobius italicus, a freshwater crayfish species where both male and female mate multiply and where last-mating males are able to actively remove previously deposited sperm. We aimed at assessing whether male sperm removal and expenditure varied according to sperm allocated by first-mating males, and according to copulation behaviour and phenotypic traits (carapace length, chelae length and relative chelae asymmetry) of second-mating males. Second-mating males did not adjust their ejaculate size in relation to first-mating male ejaculate, nor to the first-mating male’s sperm removed. Moreover, the amount of sperm removed by second-mating males increased with increasing first-mating males ejaculate size, and first-mating male sperm remaining after removal did not correlate with the original first-mating male ejaculate size. Interestingly, the amount of sperm removed by second-mating males decreased with increasing relative chelae asymmetry, while increasing with male body size. However, second-mating (but not first-mating) asymmetric-clawed males produced larger ejaculates than symmetric-clawed ones. Importantly, the proportion of second-mating male sperm remaining after the two matings did not vary with relative chelae asymmetry nor with body size of second-mating males. Thus, small, asymmetric-clawed crayfish males appear to adopt sperm allocation tactics that allow them to fully compensate for their inferior sperm removal ability.     

Arsenic release from pyrite ash waste over an active hydrogeological system and its effects on water quality

Environmental Science and Pollution Research - Arsenic is a potentially toxic element of concern for environmental compartments, and it is a frequent pollutant in many abandoned industrial sites....     

Assessment of the Viability of NIH3T3 Fibroblast Cells Cultured in Polymer Matrices with rhGH

Developing a biomaterial that functions as a scaffold (osteoconductor), combined with a growth factor (osteoinductor), is of great interest for clinical application in oral and maxillofacial surgery. Growth hormone (GH) is a good candidate, as it is a major regulator of postnatal bone growth and remodeling. Pure PLGA and 70/30 PLGA/PCL matrices were prepared by the solvent evaporation method, combined or not with GH, and tested for toxicity and cell viability using an MTT assay with NIH3T3 mouse cells (ATCC). Cell toxicity was assessed at 24, 48, 72 h, and 7 days of biomaterial exposure to culture medium. All polymers had high cell viability rates. However, from 48 h onwards, the groups with GH-polymer combinations had better results than the polymer groups without association with GH when compared to the control group. At 7 days of culture, only the pure PLGA matrix showed a significant difference from the control group. These results may suggest a preference of cells for the presence of GH in the biomaterial in culture medium, especially in the PLGA matrix. GH appeared to contribute to the increase in cell viability observed at some assessment time points, especially when combined with PLGA as compared to pure PLGA.     

Study of the operational conditions for anaerobic digestion of urban solid wastes

This paper describes an experimental evaluation of anaerobic digestion technology as an option for the management of organic solid waste in developing countries. As raw material, a real and heterogeneous organic waste from urban solid wastes was used. In the first experimental phase, seed selection was achieved through an evaluation of three different anaerobic sludges coming from wastewater treatment plants. The methanization potential of these sludges was assessed in three different batch digesters of 500 mL, at two temperature levels. The results showed that by increasing the temperature to 15 degrees C above room temperature, the methane production increases to three times. So, the best results were obtained in the digester fed with a mixed sludge, working at mesophilic conditions (38-40 degrees C). Then, this selected seed was used at the next experimental phase, testing at different digestion times (DT) of 25, 20 and 18 days in a bigger batch digester of 20 L with a reaction volume of 13 L. The conversion rates were registered at the lowest DT (18 days), reaching 44.9 L/kg(-1) of wet wasteday(-1). Moreover, DT also has a strong influence over COD removal, because there is a direct relationship between solids removal inside the reactor and DT.     

Analysis of indoor gaseous formic and acetic acid, using radial diffusive samplers

A diffusive sampling method for the determination of gaseous acetic and formic acids, using a radial symmetry diffusive sampler, has been optimised for a 7-day exposure time in this study. Sampling rate determinations were performed on data obtained from a dynamic exposure chamber, simulating the indoor conditions of an empty, closed, room, at room temperature and minimal wind speed. Analysis has been performed by means of ion chromatography. The sampling rates for formic acid concentrations of 128 microg m(-3) and 1248 microg m(-3) were determined to be 91.2 +/- 3.9 ml min(-1) and 111.6 +/- 2.8 ml min(-1), respectively. The acetic acid sampling rate was independent of the concentration in the range 160 microg m(-3)-1564 microg m(-3), and amounted to 97.3 +/- 3.1 ml min(-1). Experimentally determined sampling rates showed deviations of 3% for acetic acid, and 3-21% for formic acid, in relation to theoretically derived values. The blank values were as low as 1.69 +/- 0.07 microg for formic acid and 1.21 +/- 0.14 microg for acetic acid, and detection limits lower than 0.5 microg m(-3) could be achieved, which is an improvement of 98-99% compared to previously validated diffusive sampling methods. This study describes the first step of an extended validation program in which the applicability of these types of samplers for the measurement of organic acids will be validated and optimised for the environmental conditions typical for museum showcases.     

Characterisation of sulphide-bearing waste-rock dumps using electrical resistivity imaging: the case study of the Rio Marina mining district (Elba Island, Italy)

Sulphide-bearing mine dumps are potential sources of pollution when acid mine drainage (AMD) occurs. Because the generation of AMD depends on the volume and composition of waste materials, their characterisation is crucial for the evaluation of geochemical hazards and for the design of remediation strategies to minimise their environmental impact. In this paper, a cost-effective strategy for the characterisation of an inactive mine dump in the Rio Marina mining district (Elba Island, Italy) using earth resistivity imaging (ERI) is presented. As no information regarding the nature of waste rocks is found in reports for the mine, five ERI profiles were acquired at the top of the waste pile. The results show that waste rocks are heterogeneous with a maximum thickness of 30 m. Due to the large amounts of dispersed sulphide minerals, the waste rocks are characterised by an electrically conductive geophysical signature in comparison to the surrounding resistive metamorphic bedrock. A geostatistical approach was adopted to estimate the elevation of the edges of the mine dump, and the net volume of the waste rocks was computed through a raster analysis of the elevations of the upper and lower boundaries of the mine dump. High-conductivity anomalies were detected within the core of the mine dump. The integration of the hydrogeological, geochemical and geological framework of the Rio Marina mining district suggests that these anomalies could be a geophysical signature of subsurface regions where AMD is currently generated or stored, thus representing sources of environmental pollution.     

An environmental pressure index proposal for urban development planning based on the analytic network process

This paper introduces a new approach to prioritize urban planning projects according to their environmental pressure in an efficient and reliable way. It is based on the combination of three procedures: (i) the use of environmental pressure indicators, (ii) the aggregation of the indicators in an Environmental Pressure Index by means of the Analytic Network Process method (ANP) and (iii) the interpretation of the information obtained from the experts during the decision-making process.The method has been applied to a proposal for urban development of La Carlota airport in Caracas (Venezuela). There are three options which are currently under evaluation. They include a Health Club, a Residential Area and a Theme Park. After a selection process the experts chose the following environmental pressure indicators as ANP criteria for the project life cycle: used land area, population density, energy consumption, water consumption and waste generation. By using goal-oriented questionnaires designed by the authors, the experts determined the importance of the criteria, the relationships among criteria, and the relationships between the criteria and the urban development alternatives.The resulting data showed that water consumption is the most important environmental pressure factor, and the Theme Park project is by far the urban development alternative which exerts the least environmental pressure on the area. The participating experts coincided in appreciating the technique proposed in this paper is useful and, for ranking ordering these alternatives, an improvement from traditional techniques such as environmental impact studies, life-cycle analysis, etc.     

Prospective ecological risk assessment of sediment resuspension in an estuary

This study assesses potential ecological risk of resuspended sediment in the water column during the construction of a viaduct in the estuary of the Ulla river (Galicia, NW Iberian Peninsula), a shellfish production area. Chemical analyses and toxicity bioassays with elutriates were performed with sediments from the area where the three pillars of the viaduct will be located (CT1, CT2 and CT3) and a reference sediment (A2). Acute toxicity of the elutriate was evaluated in five species of three trophic levels (Isochrysis galbana, Paracentrotus lividus, Mytilus galloprovincialis, Venerupis pullastra and Siriella armata). The sediments of the pillars showed moderate levels of contamination by trace elements (Cu, Cr). Clam and sea urchin embryo-larval toxicity tests showed slightly higher sensitivity than mussel embryo tests, and toxicity was not detected for phytoplankton and mysid bioassays. The predicted no-effect environmental concentration (PNEC) was calculated from the arithmetic mean of the lowest calculated EC(50)s for each sampling site. The predicted environmental concentration (PEC) was estimated from a simple dilution model and the PEC/PNEC ratio was calculated according to different scenarios of resuspension. Negligible ecological risk in the water column is expected during construction of the pillars.     

Feeding macroecology of territorial damselfishes (Perciformes: Pomacentridae)

The present study provides the first analysis of the feeding macroecology of territorial damselfishes (Perciformes: Pomacentridae), a circumtropical family whose feeding and behavioral activities are important in structuring tropical and subtropical reef benthic communities. The analyses were conducted from data collected by the authors and from the literature. A strong positive correlation was observed between bite rates and sea surface temperature (SST) for the genus Stegastes. A negative correlation was found between bite rates and mean body size for the genera Stegastes and Pomacentrus, but this relationship was not significant when all territorial pomacentrids were analyzed together. A negative correlation between body size and SST was observed for the whole group and for the genera Stegastes, and Pomacentrus. No relationship was found between territory size and feeding rates. Principal Components Analysis showed that differences in feeding rates accounted for most of the variability in the data. It also suggested that body size may be important in characterizing the different genera. In general, tropical species are smaller and have higher bite rates than subtropical ones. This study extended the validity of Bergmann’s rule, which states that larger species or larger individuals within species occur towards higher latitudes and/or lower temperatures, for an important group of reef fishes. The identification of large-scale, robust ecological patterns in the feeding ecology of pomacentrid fishes may establish a foundation for predicting large-scale changes in reef fish assemblages with expected future changes in global SST.     

New Fe-immobilized natural bentonite plate used as photo-Fenton catalyst for organic pollutant degradation

Novel photo-Fenton catalysts were prepared by immobilizing iron species on commercial bentonite plates via two methods: (1) ion exchange reaction (Fe³⁺ vs. Na⁺) by aqueous suspension powder-clay/FeCl₃ followed by plate preparation, and (2) forced hydrolysis of Fe(NO₃)₃ onto a prefabricated clay plate. The last method led to a more photo-active Fe-oxide/bentonite plate. This material allowed, at a non-adjusted initial pH of 5.5 and in the presence of H₂O₂, the total degradation of resorcinol and 55% mineralization in 80 and 100 min of irradiation, respectively. The reached degradation percentages were correlated to the presence of dissolved iron, demonstrating that in these processes, the homogeneous photo-Fenton reactions were mainly responsible for the resorcinol elimination.Likewise, in slurry system, where clay has normally an increased surface area, there was no increase in activity because of a reduced leached iron probably due to the diminished light penetration in the suspension. Despite the lower surface area, in comparison to that of the slurry, the clay plates have the advantage, as heterogeneous photo-catalysts, that separation of the reaction media after treatment is not needed, and thus, a potential use for batch and continuous reaction systems is proposed.