Correlates of bushmeat hunting among remote rural households in Gabon, Central Africa

Hunted wild animals (i.e., bushmeat) are a main source of protein for many rural populations in the tropics, and the unsustainable harvest of these animals puts both human food security and ecosystem functioning at risk. To understand the correlates of bushmeat consumption, we surveyed 1219 households in 121 rural villages near three newly established national parks in Gabon. Through the surveys we gathered information on bushmeat consumption, income, and material assests. In addition, we quantified land cover in a 5-km radius around the village center and distance of the village center to the nearest park boundary. Bushmeat was not a source of income for most households, but it was the primary animal protein consumed. Ninety-seven percent of households consumed bushmeat at least once during a survey period of 12 days. Income or wealth, land cover, distance of village to the nearest park boundary, and level of education of the head of the household were among the factors that significantly related to the likelihood of consuming any of the 10 most commonly consumed species of bushmeat. Household size was the predictor most strongly associated with quantities of bushmeat consumed and was negatively related to consumption. Total bushmeat consumption per adult male equivalent increased as household wealth increased and decreased as distance of villages to park boundaries increased. Bushmeat consumption at the household level was not related to unit values (i.e., price estimates for a good that typically does not have a market value; estimates derived from willingness to sell or trade the good for items of known price) of bushmeat or the price of chicken and fish as potential substitutes. The median consumption of bushmeat at the village level, however, was negatively related to village mean unit values of bushmeat across all species. Our results suggest that a lack of alternative protein sources motivated even the wealthiest among surveyed households to consume bushmeat. Providing affordable, alternative protein sources to all households would likely reduce unsustainable levels of bushmeat consumption in rural Gabon.     

Optimization of the recovery of plastics for recycling by density media separation cyclones

Material recovery processes are presented as the optimum option for recycling plastic wastes as a means of recovering hydrocarbon resources. There exist a large variety of automated material recovery processes for recycling of such wastes but each with significant limitations. Of these, the separation based on differences in densities is advocated as the optimum process either for producing recycled products or preparing wastes for subsequent recovery processing.Density separation processes based on cyclone type density media separation (DMS) is presented as an important, potential method for increasing plastics recycling process capacities. It is demonstrated to have the capacity to separate a significantly larger range of particle sizes than those presently processed industrially. The mathematical relationship for the prediction of quality of typical LARCODEMS type density media separations by particle size and density as expressed by the Ecart Probable is presented.A proposed device configuration is presented for density media separation to optimize the recovery and purity of both density fractions produced. It is also suggested that to be economically viable, a large scale of operation is required for industrial plastics recycling operations recovering and producing a number of different plastics with a purity to be used as a substitute for virgin material.     

Robustness and vulnerability of community irrigation systems: The case of the Taos valley acequias

Traditional economic and policy analysis theory has emphasized the implementation of private or public property rights regimes in order to sustainably manage natural resources. More recent work has challenged this approach by examining the strengths and weakness of common property governance of such resources. This paper contributes to this literature by analyzing the acequia irrigation communities in northern New Mexico. Through statistical analysis, we find that the acequias’ ability to maintain collective-action as estimated by a critical performance function, crop production, is aided by water sharing agreements and access to groundwater, and that it is hampered by property rights fragmentation and urbanization.     

Acute and reproductive toxicity of nano-sized metal oxides (ZnO and TiO₂) to earthworms (Eisenia fetida)

An increase in nanomaterial applications will likely lead to an increased probability of environmental exposures, raising concerns regarding the safety of these materials. Recent studies have indicated that manufactured nanomaterials, such as metal oxides, have the potential to be harmful to aquatic and terrestrial organisms. The majority of nano-metal oxide research addressing potential toxicological issues has been focused in aquatic environments with very little terrestrial data. This study characterized the acute and reproductive toxicity of zinc oxide (ZnO) and titanium dioxide (TiO(2)) to earthworms (Eisenia fetida) in a terrestrial system. Following a 14 d exposure, nano-sized ZnO on filter paper was acutely toxic to E. fetida, while nano-sized TiO(2) did not exhibit acute toxicity. In contrast, neither nano-sized ZnO nor TiO(2) exhibited acute toxicity to earthworms in sand. Both nano-sized ZnO and TiO(2), following a 4 week exposure, caused reproductive effects in earthworms in artificial soil. Overall, nano-sized ZnO exhibited greater toxicity than nano-sized TiO(2) in Eisenia fetida.     

The contribution of roadside soil to phosphorus loading in the eutrophic Lagos Lagoon, Nigeria

Roadside soils were sampled from the Lagos Lagoon catchment during the wet and dry seasons over the period 2005-2009. Lagoon sediment samples were also collected within the same period. All samples were digested with aqua regia to determine total phosphorus and extracted with 0.5 M sodium bicarbonate to determine the bioavailable fraction (Olsen-P). A segmented flow analyser method was used for analysis and good accuracy was demonstrated for two reference soils (SO-2 from CCMET and SRM 2711 from NIST). The Lagos Lagoon is a hypereutrophic water body (1270 ± 1170 μg P L(-1)), with significant areas of anoxia and water hyacinth growth. The total phosphorus concentrations in roadside soils (16 sites; mean ± 2 S.D.) were 285 ± 279 mg kg(-1) in the wet season and 424 ± 629 mg kg(-1) in the dry season, indicating that rainwater leaching is a major source of phosphorus in the lagoon. The bioavailable fractions were 5.17 ± 3.47 mg kg(-1) (2.1 ± 1.5% of the total) in the wet season and 13.0 ± 8.7 mg kg(-1) (4.3 ± 4.5% of the total) in the dry season.     

Monitoring perchlorate exposure and thyroid hormone status among raccoons inhabiting a perchlorate-contaminated site

Perchlorate is a water soluble anion that is readily accumulated in vegetation. It inhibits uptake of iodide into thyroid gland tissue, thereby reducing production of thyroid hormones. Potential raccoon food items including berries, fish, and vegetation collected at a contaminated site contained quantifiable concentrations of perchlorate as determined by ion chromatography. Therefore, we monitored resident raccoons for exposure to perchlorate by examining plasma perchlorate and thyroid hormone concentrations. Resulting analytical data failed to demonstrate perchlorate exposure among raccoons that likely consumed food items collected along perchlorate-contaminated water bodies. There were no correlations between triiodothyronine or thyroxine and thyroid stimulating hormone concentrations, but triiodothyronine concentrations in raccoon plasma were significantly higher in 2000 than in 2001 (p = 0.0081). These data suggest that natural attenuation and remedial efforts initiated in January of 2001 may have reduced perchlorate exposure among raccoons inhabiting this site from 2000 to 2001. Temporal, spatial, and analytical factors limited our ability to quantify exposure among raccoons, however, our data do not indicate that raccoons currently inhabiting this site are at risk for significant exposure to perchlorate and subsequent effects.     

Scale-dependent responses of plant biodiversity to nitrogen enrichment

Experimental studies demonstrating that nitrogen (N) enrichment reduces plant diversity within individual plots have led to the conclusion that anthropogenic N enrichment is a threat to global biodiversity. These conclusions overlook the influence of spatial scale, however, as N enrichment may alter beta diversity (i.e., how similar plots are in their species composition), which would likely alter the degree to which N-induced changes in diversity within localities translate to changes in diversity at larger scales that are relevant to policy and management. Currently, it is unclear how N enrichment affects biodiversity at scales larger than a small plot. We synthesized data from 18 N-enrichment experiments across North America to examine the effects of N enrichment on plant species diversity at three spatial scales: small (within plots), intermediate (among plots), and large (within and among plots). We found that N enrichment reduced plant diversity within plots by an average of 25% (ranging from a reduction of 61% to an increase of 5%) and frequently enhanced beta diversity. The extent to which N enrichment altered beta diversity, however, varied substantially among sites (from a 22% increase to an 18% reduction) and was contingent on site productivity. Specifically, N enrichment enhanced beta diversity at low-productivity sites but reduced beta diversity at high-productivity sites. N-induced changes in beta diversity generally reduced the extent of species loss at larger scales to an average of 22% (ranging from a reduction of 54% to an increase of 18%). Our results demonstrate that N enrichment often reduces biodiversity at both local and regional scales, but that a focus on the effects of N enrichment on biodiversity at small spatial scales may often overestimate (and sometimes underestimate) declines in regional biodiversity by failing to recognize the effects of N on beta diversity.     

Terrestrial habitat selection and strong density-dependent mortality in recently metamorphosed amphibians

To predict the effects of terrestrial habitat change on amphibian populations, we need to know how amphibians respond to habitat heterogeneity, and whether habitat choice remains consistent throughout the life-history cycle. We conducted four experiments to evaluate how the spatial distribution of juvenile wood frogs, Rana sylvatica (including both overall abundance and localized density), was influenced by habitat choice and habitat structure, and how this relationship changed with spatial scale and behavioral phase. The four experiments included (1) habitat manipulation on replicated 10-ha landscapes surrounding breeding pools; (2) short-term experiments with individual frogs emigrating through a manipulated landscape of 1 m wide hexagonal patches; and habitat manipulations in (3) small (4-m2); and (4) large (100-m2) enclosures with multiple individuals to compare behavior both during and following emigration. The spatial distribution of juvenile wood frogs following emigration resulted from differences in the scale at which juvenile amphibians responded to habitat heterogeneity during active vs. settled behavioral phases. During emigration, juvenile wood frogs responded to coarse-scale variation in habitat (selection between 2.2-ha forest treatments) but not to fine-scale variation. After settling, however, animals showed habitat selection at much smaller scales (2-4 m2). This resulted in high densities of animals in small patches of suitable habitat where they experienced rapid mortality. No evidence of density-dependent habitat selection was seen, with juveniles typically choosing to remain at extremely high densities in high-quality habitat, rather than occupying low-quality habitat. These experiments demonstrate how prediction of the terrestrial distribution of juvenile amphibians requires understanding of the complex behavioral responses to habitat heterogeneity. Understanding these patterns is important, given that human alterations to amphibian habitats may generate extremely high densities of animals, resulting in high density-dependent mortality.     

Dust emission calculations in open storage piles protected by means of barriers, CFD and experimental tests

The importance of open mineral storage piles in bulk solids port terminals have increased considerably in recent years in Europe and USA (in Spain, great extensions of transoceanic ports are being made) to address the increasing demand of raw material importation due to local mining operation closure. These storage piles are affected by the climatologically processes and the dust emission to the atmosphere, causing repercussions to health and environmental, which is intimately related to the air velocity, according to USEPA studies, maximum ratio of dust emission emitted from CFD and software Ansys CFX 10.0 is determined. In addition, an emission variability study based on the pile distance of different height solid barriers is developed, reducing the emission to 66%. The studies have been contrasted by published investigations and industrial measurement.     

Characterisation of esterases as potential biomarkers of pesticide exposure in the lugworm Arenicola marina (Annelida: Polychaeta)

Here, we identify and characterise cholinesterase (ChE) and carboxylesterase (CbE) activities in the body tissues of the sediment dwelling worm Arenicola marina. Exposure to the organophosphorus pesticide azamethiphos yielded an in vitro IC50 of 5 microg l(-1) for propionylcholinesterase (PChE). PChE was significantly inhibited in vivo after a 10 day exposure to 100 microg l(-1) azamethiphos, equivalent to the recommended aquatic application rate (ANOVA; F=2.75, P=0.033). To determine sensitivity to environmental conditions, A. marina were exposed for 10 days to field collected sediments. PChE activity was significantly lower in worms exposed to sediments from an estuary classified to be at high risk from point source pollution by the UK Environment Agency (ANOVA; F=15.33, P<0.001). Whilst causality cannot be directly attributed from these latter exposures, they provide an important illustration of the potential utility of esterase activity as a biomarker of environmental quality in this ecologically relevant sentinel species.