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31.
Clibanarius longitarsus (De Haan), a hermit crab, feeds by means of both micro- and macrofeeding. Microfeeding is of two types: filter feeding and deposit feeding. In macrofeeding, the animal depends mainly on green algae, barnacles and some worms, etc. In filter feeding, the hermit crab uses its paired antennules for trapping microorganisms drawn into the water current created by the second and third maxillipeds; the antennae do not play any role in filter feeding. In deposit feeding, the hermit crab uses its chelae as well as pereiopods for toughing and obtaining detritus food material. In macrofeeding, the organism employs sharp chelae to collect small pieces of muscle from barnacles and then transfer them to the inner mouth parts. In algal feeding, the chelae as well as maxillipeds help in collecting and moving food material towards the mouth. In this investigation functional organisation ofC. longitarsus mouth parts was studied in detail with reference to the various feeding mechanisms, in specimens collected from the intertidal region of Bheemunipatnam, Andra Pradesh, India, in 1988 and 1989.  相似文献   
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This paper reports an approach to the assessment of the validity of environmental monitoring data--a 'data filter'. The strategy has been developed through the UK National Marine Analytical Quality Control (AQC) Scheme for application to data collected for the UK National Marine Monitoring Plan, although the principles described are applicable more widely. The proposed data filter is divided into three components: Part A, 'QA/QC'--an assessment of the laboratory's practices in Quality Assurance/Quality Control; Part B, 'fitness for purpose'--an evaluation of the standard of accuracy that can be demonstrated by activities in (A), in relation to the intended application of the data; and Part C, the overall assessment on which data will be accepted as usable or rejected as being of suspect quality. A pilot application of the proposed approach is reported. The approach described in this paper is intended to formalise the assessment of environmental monitoring data for fitness for a chosen purpose. The issues important to fitness for purpose are discussed and assigned a relative priority order on which to judge the reliability/usefulness of monitoring data.  相似文献   
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A diverse range of microorganisms capable of growth on phenylacetic acid as the sole source of carbon and energy were isolated from soil. Sixty six different isolates were identified and grouped according to 16S rRNA gene RFLP analysis. Subsequent sequencing of 16S rDNA from selected strains allowed further characterization of the phenylacetic acid degrading population isolated from soil. Nearly half (30) of the isolates are Bacillus species while the rest of the isolates are strains from a variety of genera namely, Arthrobacter, Pseudomonas, Rhodococcus, Acinetobacter, Enterobacter, Flavobacterium, and Paenibacillus. Sixty-one of the sixty-six strains reproducibly grew in defined minimal liquid culture medium (E2). All strains isolated grew when at least one hydroxylated derivative of phenylacetic acid was supplied as the carbon source, while 59 out of the 61 strains tested, accumulated ortho-hydroxyphenylacetic acid in the assay buffer; when pulsed with phenylacetic acid. Oxygen consumption experiments failed to indicate a clear link between phenylacetic acid and hydroxy-substituted phenylacetic acid in isolates from a broad range of genera.  相似文献   
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This article provides a concise review of published literature pertaining to sampling and analytical methodologies, aerometric studies, source identification techniques and modeling activities for the elements arsenic, cadmium, nickel, lead, vanadium, zinc, cobalt, chromium, copper, iron, mercury, manganese, selenium and antimony, and their compounds, associated with airborne particulate matter. Sampling techniques discussed include filtration and inertial separation. Analytical methodologies such as atomic absorption and atomic emission spectrometry, neutron activation analysis, and X-ray fluorescence spectrometry are summarized. Data on atmospheric levels of 14 trace elements are presented in summary form from numerous studies in remote, rural and urban areas, and generally indicate that concentrations measured at rural locations are several orders of magnitude lower than those measured for urban areas. Source identification methodologies are discussed in terms of advantages and disadvantages, and various applications are cited for the following categories: size differentiation, enrichment factors, chemical mass balance, and multivariate models. Provided that reliable trace element data are available for both the source and the receptor, chemical mass balance and multivariate methods can account for up to 80 percent of all sources contributing to the observed ambient air concentration. Wet and dry deposition processes are reviewed and environmental measurement data are provided for each element for remote, rural and urban locations. Both wet and dry deposition fluxes need to be considered for trace elements when estimating the total annual amounts of various trace elements deposited at a particular locale. Global cycles and trace element budgets are introduced in the context of the types of models currently in use. Limitations include inadequate global scale surveys of heavy metal concentrations and the lack of knowledge of sources and/or sinks.  相似文献   
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The current perception that climate change is the principal threat to biodiversity is at best premature. Although highly relevant, it detracts focus and effort from the primary threats: habitat destruction and overexploitation. We collated causes of vertebrate extinctions since 1900, threat information for amphibia, birds, and mammals from the IUCN Red List, and scrutinized others’ attempts to compare climate change with commensurate anthropogenic threats. In each analysis, none of the arguments founded on climate change's wide-ranging effects are as urgent for biodiversity as those for habitat loss and overexploitation. Present conservation efforts must refocus on these issues. Conserving ecosystems by focusing on these major threats not only protects biodiversity but is the only available, economically viable, global strategy to reverse climate change.  相似文献   
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Hosseini PR  Dhondt AA  Dobson AP 《Ecology》2006,87(12):3037-3046
In this paper we quantify the rate of spread of the newly emerged pathogen Mycoplasma gallisepticum of the House Finch, Carpodacus mexicanus, in its introduced range. We compare and contrast the rapid, yet decelerating, rate of spread of the pathogen with the slower, yet accelerating rate of spread of the introduced host. Comparing the rate of spread of this pathogen to pathogens in terrestrial mammalian hosts, we see that elevation and factors relating to host abundance restrict disease spread, rather than finding any major effects of discrete barriers or anthropogenic movement. We examine the role of seasonality in the rate of spread, finding that the rate and direction of disease spread relates more to seasonality in host movement than to seasonality in disease prevalence. We conclude that asymptomatic carriers are major transmitters of Mycoplasma gallisepticum into novel locations, a finding which may also be true for many other diseases, such as West Nile Virus and avian influenza.  相似文献   
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Pathogens pose serious threats to human health, agricultural investment, and biodiversity conservation through the emergence of zoonoses, spillover to domestic livestock, and epizootic outbreaks. As such, wildlife managers are often tasked with mitigating the negative effects of disease. Yet, parasites form a major component of biodiversity that often persist. This is due to logistical challenges of implementing management strategies and to insufficient understanding of host–parasite dynamics. We advocate for an inclusive understanding of molecular diversity in driving parasite infection and variable host disease states in wildlife systems. More specifically, we examine the roles of genetic, epigenetic, and commensal microbial variation in disease pathogenesis. These include mechanisms underlying parasite virulence and host resistance and tolerance, and the development, regulation, and parasite subversion of immune pathways, among other processes. Case studies of devil facial tumor disease in Tasmanian devils (Sarcophilus harrisii) and chytridiomycosis in globally distributed amphibians exemplify the broad range of questions that can be addressed by examining different facets of molecular diversity. For particularly complex systems, integrative molecular analyses present a promising frontier that can provide critical insights necessary to elucidate disease dynamics operating across scales. These insights enable more accurate risk assessment, reconstruction of transmission pathways, discernment of optimal intervention strategies, and development of more effective and ecologically sound treatments that minimize damage to the host population and environment. Such measures are crucial when mitigating threats posed by wildlife disease to humans, domestic animals, and species of conservation concern.  相似文献   
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