Critics of the Endangered Species Act have asserted that is protects an inordinate number of subspecies and populations, in addition to full species, and that the scientific rationale for listing decisions is absent or weak. We reviewed all U.S. plants and animals proposed for listing or added to the endangered species list from 1985 through 1991 to determine the relative proportion of species, subspecies, and populations, and their rarity at time of listing. Approximately 80% of the taxa added to the list were full species, 18% were subspecies, and 2% were distinct populations segments of more widespread vertebrate species. The proportion of subspecies and populations was considerably higher among birds and mammals than among other groups. The median populations size at time of listing for vertebrate animals was 1075 individuals; for invertebrate animals it was 999. The median population size of a plant at time of listing was less than 120 individuals. Earlier listing of declining species could significantly improve the likelihood of successful recovery, and it would provide land managers and private citizens with more options for protecting vanishing plants and animals at less social or economic cost. 相似文献
Laboratory experiments conducted during 1987 on Appledore Island, Maine, USA, tested whether feeding preference or the absence of an attractant was the cause for the occurrence of beds of Codium fragile ssp. tomentosoides (herein referred to as Codium fragile) within rocky barrens grazed clear of kelp by the sea urchin Strongylocentrotus droebachiensis. Consumption of C. fragile in single-diet experiments (1 seaweed/sea urchin) was highly variable and was not significantly different from that for several other seaweeds (Agarum cribrosum, Ascophyllum nodosum, Chondrus crispus, and Laminana saccharina) important in the field diet of the green sea urchin. In multiple-diet experiments (5 seaweeds/sea urchin) significantly less Codium fragile was eaten than Chondrus crispus, but significantly more Codium fragile was eaten than A. cribrosum. Chemosensory experiments suggest that C. fragile does not attract the sea urchin. Sea urchins are unable to detect C. fragile but will eat it when they come in contact with it. 相似文献
Assessment of the food chain mobility of heavy metals inthe natural ecosystem receives more attention nowadays. Inthe present study, mulberry-silkworm food chain has beenfocused as a templet to assess the biomobility of heavymetals in soil-higher plant-insect hierarchy. Both in thecase of Cd and Cu treatments, higher mobility wasobserved in the level-1 (soil–root) followed by level-3(leaf–larva), level-4 (larvae–faecal) and level-2(root–leaf). Consequently, roots accumulated more amountsof Cd and Cu, with a limited transport to the leaves.Among the two metals (Cd and Cu) tested, in the plant,the transfer potential of Cd exceeds that of Cu. Whereasin the case of leaf–larval transfer, Cu precedes overCd. Accumulation of Cd and Cu in all the levels (1–4)tested showed a concentration dependent increase, except inthe level 4 (larva–faecal) of Cd treatment where adeclining trend was noticed. 相似文献
Environmental Science and Pollution Research - In the current century, the G7 countries have attached more importance to energy security, and have prioritized low-carbon sources which have... 相似文献
Abstract In the United States, emission processing models such as Emissions Modeling System-2001 (EMS-2001), Emissions Preprocessor System-Version 2.5 (EPS2.5), and the Sparse Matrix Operator Kernel Emissions (SMOKE) model are currently being used to generate gridded, hourly, speciated emission inputs for urban and regional-scale photochemical models from aggregated pollutant inventories. In this study, two models, EMS-2001 and SMOKE, were applied with their default internal data sets to process a common inventory database for a high ozone (O3) episode over the eastern United States using the Carbon Bond IV (CB4) chemical speciation mechanism. A comparison of the emissions processed by these systems shows differences in all three of the major processing steps performed by the two models (i.e., in temporal allocation, spatial allocation, and chemical speciation). Results from a simulation with a photochemical model using these two sets of emissions indicate differences on the order of ±20 ppb in the predicted 1-hr daily maximum O3 concentrations. It is therefore critical to develop and implement more common and synchronized temporal, spatial, and speciation cross-reference systems such that the processes within each emissions model converge toward reasonably similar results. This would also help to increase confidence in the validity of photochemical grid model results by reducing one aspect of modeling uncertainty. 相似文献
Environmental Science and Pollution Research - Marine and freshwater pollution caused by transport of invasive species in shipping ballast water is a major global problem and will increase in... 相似文献
In this research work, the conventional single slope still (CSS) with egg shells of breed Gallus gallus domesticus cascara as sensible heat storage (SHS) material are studied experimentally to enhance the yield. In this experimental investigation, the proposed single slope still (PSS) with SHS material was made in comparison with the CSS to evaluate the productivity of fresh water under the same ambient conditions. Comparatively, this PSS has higher thermal conductivity than the CSS. The yield obtained from the PSS is 2.46 L/m2, while the yield from the CSS is 2.07 L/m2. The average rate at which the rise of output fresh water obtained from the PSS is 18% more than the fresh water output obtained from the CSS. The daily energy efficiency of the PSS is 26.07%, and for the CSS, it is only 22.25%. The daily exergy efficiency of the PSS is 2.36%, and for the CSS, it is only 1.67%. Since using the egg shell will employ as organic waste management and modification in this still is economical, less initial, and maintenance cost.
Environmental Science and Pollution Research - To achieve allowable gas emission limits and eliminate the high cost and challenges associated with pre-treatment of sludge before incineration, a new... 相似文献