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701.
/ For regional analyses of species imperilment patterns, data on species distributions are available from the U.S. Fish and Wildlife Service and from the state heritage programs. We compared these two different databases as sources of best available information for regional analyses of patterns of aquatic species imperilment for 132 counties in the southern Appalachians and examined patterns produced from the databases. The heritage program database contained information about a greater number of imperiled species because species need not be federally listed as threatened or endangered to be included in this database. In the southern Appalachians, about half of imperiled molluscs and about one-fourth of imperiled fish were listed as threatened or endangered; much smaller proportions of other taxonomic groups were federally listed. Most threatened and endangered species appeared on both lists, but for about 40% of the species inconsistencies exist, notably a lack of recent records in the heritage program dataset. Numbers of species in each county were significantly different between the two datasets for Georgia, Tennessee, and Virginia, where the largest number of threatened and endangered species reside. Nevertheless, some counties always appeared as centers of imperilment, and the general spatial patterns of imperilment were similar. 相似文献
702.
This paper focuses on growth feasibility in an era of increasing scarcity of fossil fuels. A stylised dynamic model illustrates the implications of investing in smooth technological progress in the field of renewable energy. Positive rates of GDP growth sustained by fossil fuels entail, on the one hand, more income available for R&D in renewable energy sources, and on the other, an acceleration of the exhaustible resource depletion time. Our model explores such a trade-off and highlights the danger of high growth rates. Policies should target low growth rates, stimulate investment in alternative energy sources and discourage consumption growth. 相似文献
703.
Erich M. G. Fitzgerald Matthew T. Carrano Timothy Holland Barbara E. Wagstaff David Pickering Thomas H. Rich Patricia Vickers-Rich 《Die Naturwissenschaften》2012,99(5):397-405
The basal theropod dinosaur clade Ceratosauria, and its subclade Abelisauroidea, is characteristic of late Mesozoic terrestrial vertebrate faunas in western Gondwana (South America, Africa, Madagascar, and India) and Europe. Yet unambiguous records of ceratosaurs have hitherto been absent from Australia, where the theropod assemblage appears to include several typically Laurasian clades. Here, we report the first evidence of ceratosaurs (and potentially abelisauroids) from eastern Gondwana––a diagnostic astragalocalcaneum from the Aptian (121–125?Ma) of Victoria, Australia. Ceratosauria thus occurred in both western and eastern Gondwana during the Early Cretaceous. This fossil adds to the poorly known dinosaur fauna of Australia, a major clade of basal theropods, emphasising that its mid-Cretaceous theropod diversity was surprisingly cosmopolitan despite relative geographic isolation, including clades that have been thought to be typical of both Gondwana and Laurasia––Ceratosauria, Spinosauridae, Carcharodontosauria, Tyrannosauroidea, and Deinonychosauria. Such a contemporaneous association of theropod clades is unknown from other Gondwanan continents and questions the views that the late Mesozoic dinosaur fauna of Australia was dominated by Gondwanan or Laurasian elements, extreme isolation, relictualism, and/or novelty as a ‘centre of origin’. The cosmopolitan theropod fauna of Australia probably reflects the global distribution of these clades early in their history, prior to significant continental breakup. 相似文献
704.
The discrimination of infectious and inactivated viruses remains a key obstacle when using quantitative RT-PCR (RT-qPCR) to
quantify enteric viruses. In this study, propidium monoazide (PMA) and RNase pretreatments were evaluated for the detection
and quantification of infectious hepatitis A virus (HAV). For thermally inactivated HAV, PMA treatment was more effective
than RNase treatment for differentiating infectious and inactivated viruses, with HAV titers reduced by more than 2.4 log10 units. Results showed that combining 50 μM of PMA and RT-qPCR selectively quantify infectious HAV in media suspensions. Therefore,
PMA treatment previous to RT-qPCR detection is a promising alternative to assess HAV infectivity. 相似文献
705.
Patricia Prado Catherine J. Collier Javier Romero Teresa Alcoverro 《Marine Biology》2011,158(7):1473-1482
Herbivory is now recognized as an important structuring agent in seagrass meadows but the attack pattern and tissue damage
of consumers are highly variable. Nutritional preferences of herbivores and/or easy access to resources may cause differences
in biomass loss among tissues that damage the plant in functionally distinctive ways. The two main Mediterranean herbivores,
the fish Sarpa salpa (L.) and the sea urchin Paracentrotus lividus (Lmk.), remove higher amounts of intermediate and external shoot leaves, respectively. To test whether this selective feeding
can have different consequences on the allocation patterns of nutrient within plants, we simulated the effect of both herbivores
by clipping external and intermediate leaves (plus unclipped controls) of Posidonia oceanica (L.) and we measured plant tolerance in terms of shoot growth and leaf nutrient supply to new tissue using isotopic markers.
As expected, control treatments displayed high carbon and nutrient supply from external leaves (83% of the total 15N and 84% of the total 13C incorporated by the shoot). When subjected to clipping, the remaining leaves enhanced carbon and nitrogen supply compared
with the control by 16% of N and 36% of C—in the intermediate clipping—and by over 100% of N and 200% of C—in the external
clipping—to compensate for the nutrient lost. However, only in the case of fish herbivory (intermediate clipping), enhanced
supply alone was able to fully compensate for the nutrient losses. In contrast, this mechanism is not completely effective
when external leaves are clipped (urchin herbivory). Yet, the consequences of this nutrient loss under sea urchin herbivory
are not apparent from the nutrient content of the new tissue, suggesting that there are other sources of nitrogen income (uptake
or reallocation from rhizomes). Our study does not only confirm the tolerance of P. oceanica to herbivory, but also constitutes the first evidence of leaf-specific, compensatory nutrient supply in seagrasses. 相似文献
706.
Cardoso NF Lima EC Pinto IS Amavisca CV Royer B Pinto RB Alencar WS Pereira SF 《Journal of environmental management》2011,92(4):1237-1247
The cupuassu shell (Theobroma grandiflorum) which is a food residue was used in its natural form as biosorbent for the removal of C.I. Reactive Red 194 and C.I. Direct Blue 53 dyes from aqueous solutions. This biosorbent was characterized by infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption/desorption curves. The effects of pH, biosorbent dosage and shaking time on biosorption capacities were studied. In acidic pH region (pH 2.0) the biosorption of the dyes were favorable. The contact time required to obtain the equilibrium was 8 and 18 h at 298 K, for Reactive Red 194 and Direct Blue 53, respectively. The Avrami fractionary-order kinetic model provided the best fit to experimental data compared with pseudo-first-order, pseudo-second-order and chemisorption kinetic adsorption models. The equilibrium data were fitted to Langmuir, Freundlich, Sips and Radke-Prausnitz isotherm models. For both dyes the equilibrium data were best fitted to the Sips isotherm model. 相似文献
707.
Comparing Hydrogeomorphic Approaches to Lake Classification 总被引:1,自引:1,他引:0
A classification system is often used to reduce the number of different ecosystem types that governmental agencies are charged with monitoring and managing. We compare the ability of several different hydrogeomorphic (HGM)—based classifications to group lakes for water chemistry/clarity. We ask: (1) Which approach to lake classification is most successful at classifying lakes for similar water chemistry/clarity? (2) Which HGM features are most strongly related to the lake classes? and, (3) Can a single classification successfully classify lakes for all of the water chemistry/clarity variables examined? We use univariate and multivariate classification and regression tree (CART and MvCART) analysis of HGM features to classify alkalinity, water color, Secchi, total nitrogen, total phosphorus, and chlorophyll a from 151 minimally disturbed lakes in Michigan USA. We developed two MvCART models overall and two CART models for each water chemistry/clarity variable, in each case comparing: local HGM characteristics alone and local HGM characteristics combined with regionalizations and landscape position. The combined CART models had the highest strength of evidence (ωi range 0.92–1.00) and maximized within class homogeneity (ICC range 36–66%) for all water chemistry/clarity variables except water color and chlorophyll a. Because the most successful single classification was on average 20% less successful in classifying other water chemistry/clarity variables, we found that no single classification captures variability for all lake responses tested. Therefore, we suggest that the most successful classification (1) is specific to individual response variables, and (2) incorporates information from multiple spatial scales (regionalization and local HGM variables). 相似文献
708.
Karla Patricia Oliveira-Esquerre Mario Cezar Mattos 《Resources, Conservation and Recycling》2011,55(3):316-324
A methodology for water use minimization has been developed by the Clean Technology Network of Bahia over a 10 year period in joint cooperative programs with the chemical, petrochemical and copper metallurgy industries located in the largest Industrial Complex in Latin America, in Camaçari, Bahia, Brazil. The methodology comprises a set of tools including reconciled aqueous stream balances, database of aqueous streams; large scale training leading to the identification of water minimization alternatives in the processes, water reuse optimization approaches; geographical information systems as well as, consideration of the region's hydro and hydro-geological characteristics. The results of a study carried out to assess the possibility of using storm and wastewaters for industrial use is presented in this paper. The inorganic system is composed by three water reservoirs (basins) receiving stormwater contaminated with inorganic effluents, and occasionally with organics. These basins have been operated to control water flow inputs according to the capacity of the pumping outlet systems before their discharge to a submarine outfall. A mass balance was performed with historical updated data to assess water availability from the basins based on the daily volume variation and flow rate of inorganic effluent from 2001 to 2007. The study identified the possibility of recovering about 1140 m3/h of the overall 5400 m3/h consumed by the Industrial Complex at the moment. Organizational changes in the present effluent disposal and stormwater harvest systems will be required in order to maximize water recovery for industrial use. 相似文献
709.
Richard N. C. Milner Michael D. Jennions Patricia R. Y. Backwell 《Behavioral ecology and sociobiology》2011,65(7):1419-1424
Non-independent mate selection occurs when the choice behavior of a female is altered by the interactions between other females
and males. In the fiddler crab Uca mjoebergi, males court mate-searching females by waving their one greatly enlarged claw. When a female approaches a male, he initiates
high-intensity waving. We conducted one natural mate choice experiment and two mate choice experiments using custom-built
robotic crabs. We show that the decision of one female to approach a group of males increases the probability that another
female will approach and visit a male from the same group. We suggest that this behavior is best explained by the ‘stimulus
enhancement’ hypothesis, where the presence of a female near a group of males makes them more likely to be detected by other
females due to an increase in male display rate. 相似文献
710.
Assessing landscape structure and pattern fragmentation in semiarid ecosystems using patch-size distributions 总被引:4,自引:0,他引:4
Spatial vegetation patterns are recognized as sources of valuable information that can be used to infer the state and functionality of semiarid ecosystems, particularly in the context of both climate and land use change. Recent studies have suggested that the patch-size distribution of vegetation in drylands can be described using power-law metrics, and that these scale-free distributions deviate from power-law linearity with characteristic scale lengths under the effects of increasing aridity or human disturbance, providing an early sign of desertification. These findings have been questioned by several modeling approaches, which have identified the presence of characteristic scale lengths on the patch-size distribution of semiarid periodic landscapes. We analyze the relationship between fragmentation of vegetation patterns and their patch-size distributions in semiarid landscapes showing different degree of periodicity (i.e., banding). Our assessment is based on the study of vegetation patterns derived from remote sensing in a series of semiarid Australian Mulga shrublands subjected to different disturbance levels. We use the patch-size probability density and cumulative probability distribution functions from both nondirectional and downslope analyses of the vegetation patterns. Our results indicate that the shape of the patch-size distribution of vegetation changes with the methodology of analysis applied and specific landscape traits, breaking the universal applicability of the power-law metrics. Characteristic scale lengths are detected in (quasi) periodic banded ecosystems when the methodology of analysis accounts for critical landscape anisotropies, using downslope transects in the direction of flow paths. In addition, a common signal of fragmentation is observed: the largest vegetation patches become increasingly less abundant under the effects of disturbance. This effect also explains deviations from power-law behavior in disturbed vegetation which originally showed scale-free patterns. Overall, our results emphasize the complexity of structure assessment in dryland ecosystems, while recognizing the usefulness of the patch-size distribution of vegetation for monitoring semiarid ecosystems, especially through the cumulative probability distributions, which showed high sensitivity to fragmentation of the vegetation patterns. We suggest that preserving large vegetation patches is a critical task for the maintenance of the ecosystem structure and functionality. 相似文献