998 resultados para disturbed area
Resumo:
Thecamoebians were examined from 123 surface sediment samples collected from 45 lakes in the Greater Toronto Area (GTA) and the surrounding region to i) elucidate the controls on faunal distribution in modern lake environments; and ii) to consider the utility of thecamoebians in quantitative studies of water quality change. This area was chosen because it includes a high density of lakes that are threatened by urban development and where water quality has deteriorated locally as a result of contaminant inputs, particularly nutrients. Canonical Correspondence analysis (CCA) and a series of partial CCAs were used to examine species-environment relationships. Twenty-four environmental variables were considered, including water properties (e.g. pH, DO, conductivity), substrate characteristics, nutrient loading, and environmentally available metals. The thecamoebian assemblages showed a strong association with Olsen's Phosphorus, reflecting the eutrophic status of many of the lakes, and locally to elevated conductivity measurements, which appear to reflect road salt inputs associated with winter de-icing operations. A transfer function was developed for Olsen P using this training set based on weighted averaging with inverse deshrinking (WA Inv). The model was applied to infer past changes in Phosphorus enrichment in core samples from several lakes, including eutrophic Haynes Lake within the GTA. Thecamoebian-inferred changes in sedimentary Phosphorus from a 210Pb dated core from Haynes Lake are related to i) widespread introduction of chemical fertilizers to agricultural land in the post WWII era; ii) a steep decline in Phosphorous with a change in agricultural practices in the late 1970s; and iii) the construction of a golf course in close proximity to the lake in the early 1990s. This preliminary study confirms that thecamoebians have considerable potential as indicators of eutrophication in lakes and can provide an estimate of baseline conditions.
Resumo:
Although exogenous factors such as pollutants can act on endogenous drivers (e.g. dispersion) of populations and create spatially autocorrelated distributions, most statistical techniques assume independence of error terms. As there are no studies on metal soil pollutants and microarthropods that explicitly analyse this key issue, we completed a field study of the correlation between Oribatida and metal concentrations in litter, organic matter and soil in an attempt to account for spatial patterns of both metals and mites. The 50-m wide study area had homogenous macroscopic features, steep Pb and Cu gradients and high levels of Zn and Cd. Spatial models failed to detect metal-oribatid relationships because the observed latitudinal and longitudinal gradients in oribatid assemblages were independent of the collinear gradients in the concentration of metals. It is therefore hypothesised that other spatially variable factors (e.g. fungi, reduced macrofauna) affect oribatid assemblages, which may be influenced by metals only indirectly. (C) 2009 Elsevier Ltd. All rights reserved.
Resumo:
The main aims of the present study, conducted in the framework of the MONIQUA-Egadi Scientific Project, were twofold: first, to make the first step in the development and validation of an ecotoxicological approach for the assessment of marine pollution in coastal environments on the basis of a set of biomarker responses in new sentinel species; and second, to obtain preliminary information on environmental quality in an Italian marine protected area, the Egadi Islands (Sicily). Several cytochrome P450-dependent mixed-function oxidase activities were measured in the following sentinel species: rainbow wrasse Coris julis, gastropod limpet Patella caerulea, and sea urchin Paracentrotus lividus. The results suggest that specimens from the Favignana Harbor may be exposed to P450 inducers, whereas most of the other sites seem to share similar environmental quality. The proposed approach has potential for assessment of environmental quality in marine protected areas.
Resumo:
The extent to which climate change might diminish the efficacy of protected areas is one of the most pressing conservation questions. Many projections suggest that climate-driven species distribution shifts will leave protected areas impoverished and species inadequately protected while other evidence suggests that intact ecosystems within protected areas will be resilient to change. Here, we tackle this problem empirically. We show how recent changes in distribution of 139 Tanzanian savannah bird species are linked to climate change, protected area status and land degradation. We provide the first evidence of climate-driven range shifts for an African bird community. Our results suggest that the continued maintenance of existing protected areas is an appropriate conservation response to the challenge of climate and environmental change.
Resumo:
One of the many results of the Global Financial Crisis was the insight that the financial sector is under-taxed compared to other industries. In light of the huge bailouts and continued subsidies for financial institutions that are characterized as too-big-to-fail demands came on the agenda to make finance pay for the mega-crisis it caused. The most prominent examples of such taxes are a Financial Transaction Tax (FTT) and a Financial Activities Tax (FAT). Possible effects of such taxes on the economic constitution and increasingly in particular on the European Single Market have been discussed controversially over the last decades already. Especially with the decision of eleven EU member states to adapt an FTT using the enhanced cooperation procedure a number of additional legal challenges for implementing such a tax have emerged. This paper analyzes how tax measures of indirectly regulating the financial industry differ, what legal challenges they pose, and what their overall contribution would be in making the financial system more stable and resilient. It also analyzes the legal arguments against enhanced cooperation in this area and the legal issues related to the British lawsuit against the Commission’s Directive proposal in the European Court of Justice on grounds of the extra-territoriality application of tax. The paper concludes that the feasibility of an FTT is legally sound and given the FTT’s advantages over a FAT the EU Directive should be implemented as a first step for a European-wide FTT. However, significant uncertainties about its implementation remain at this stage.
Resumo:
The modern stereologic method of vertical sections was applied to the retina as a means of generating unbiased estimates of three-dimensional structure. The method is illustrated with real data on the volume and surface area of the capillary basement membrane from the central retina of the rat. Novel methods of estimating the volume of retina sampled and of creating accurate vertical sections are described. The advantages of using stereologic methods to generate quantitative information on the three-dimensional structure of the retina are discussed and compared to those of previous quantitative methods that provide data on two-dimensional structure only.
Resumo:
Body Area Networks are unique in that the large-scale mobility of users allows the network itself to travel across a diverse range of operating domains or even to enter new and unknown environments. This network mobility is unlike node mobility in that sensed changes in inter-network interference level may be used to identify opportunities for intelligent inter-networking, for example, by merging or splitting from other networks, thus providing an extra degree of freedom. This paper introduces the concept of context-aware bodynets for interactive environments using inter-network interference sensing. New ideas are explored at both the physical and link layers with an investigation based on a 'smart' office environment. A series of carefully controlled measurements of the mesh interconnectivity both within and between an ambulatory body area network and a stationary desk-based network were performed using 2.45 GHz nodes. Received signal strength and carrier to interference ratio time series for selected node to node links are presented. The results provide an insight into the potential interference between the mobile and static networks and highlight the possibility for automatic identification of network merging and splitting opportunities. © 2010 ACM.