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81.
82.
Ibtihel Saidi Olfa Ben Said Jamel Ben Abdelmalek Soufiane Jouili Luis Chicharo Hamouda Beyrem 《Chemistry and Ecology》2013,29(8):746-774
ABSTRACTThe aim of this study was to assess the consequences of human impact on the characteristics of sediments heavy metal concentration, grain size and its influence on the structure of the microbial and meiofaunal community assemblages. A survey was carried out in July 2013 within six sites located in the Bizerte Lagoon (Tunisia), both downstream and upstream of industrial effluents. The highest total sediment metal concentrations were detected in stations located close to the industrial sewage discharge points. In these stations, the lowest densities of the total meiofauna (33?±?13?ind/10?cm?2) and conversely the highest densities of cultivable bacteria that are heavy metal resistant have been reported (16?±?80.34?CFU?g?1). Univariate (ANOVA) and multivariate (MDS/CCA) analyses demonstrate high dissimilarity (0.06) in meiofaunal and bacterial community structures between downstream and upstream industrial sewages. Furthermore, canonical correspondence analysis CCA results indicated that heavy metal sediment contamination promoted bacteria that are resistant to heavy metals, while heterotrophic bacteria supported the development of meiofauna taxa. The results highlight the importance of bacteria/meiofauna interactions, as both meiofaunal and microbial communities give indications of the ecological impact of heavy metal contamination in sediment. 相似文献
83.
Previous studies that have investigated relationships between the lunar cycle and recreational fishing success have all suffered from various problems—most notably, the failure to account for potential confounders in a statistically rigorous manner. We propose methods to account for season, fisher identity, fishing effort, day, and variation in biomass, all of which have previously either been omitted or handled in an ad hoc way. These are applied to two sets of data on recreational fishing of the snapper Pagrus auratus in New Zealand. In addition to estimating effects due to lunar phase, we also implement these methods to analyse the performance of a lunar-based indigenous M ${{\bar{\mathrm{a}}}}$ ori fishing calendar. Recreational fishers in New Zealand often make use of such calendars in order to predict fishing success on specific days, however little is known about the performance of such predictions or whether they hold any practical use to the everyday angler. A relationship between lunar phase and fishing success is identified, as well as support for some aspects of the M ${{\bar{\mathrm{a}}}}$ ori fishing calendar predictions. The magnitudes of these effects are small, however, casting doubt on the practical relevance of lunar based fishing predictions. In addition to the known seasonal trend associated with annual migration, an unexpected second trend is detected, and postulated to be associated with intense local fishing pressure over the summer vacation period. 相似文献
84.
中国西北旱区农业水土资源利用情景潜力研究 总被引:7,自引:1,他引:6
西北旱区水土资源供需矛盾突出,同时作为该区农业生产的瓶颈因素,决定该区经济社会生态可持续发展,因此有必要开展西北旱区农业水土资源相结合的空间情景潜力研究。论文采用水土资源匹配指数计算分析了西北旱区现状年(2010年)农业水土资源的匹配状况,采用农业水土资源利用潜力估算方法计算了西北旱区2020、2030年RCP 8.5和RCP 4.5两种情景下的农业水土资源利用潜力,实现了西北旱区农业水土资源利用潜力的可视化表达。结果表明:2020和2030年RCP 8.5和RCP 4.5排放情景下,相对于2010年,西北旱区各省2020和2030年的总农业水资源量和种植面积均减小。西北旱区6省份2020和2030年两种情景下整体综合效益和整体潜力值均为正,表明各省种植结构整体得到了优化。2020年RCP 8.5和RCP 4.5情景下,西北旱区农业水土资源利用潜力分布范围分别在-0.10×104~0.83×104元/hm2之间和 -1.20×104~0.97×104元/hm2之间;2030年RCP 8.5和RCP 4.5情景下,农业水土资源利用潜力分布范围分别在-0.39×104~2.17×104元/hm2之间和-0.36×104~1.66×104元/hm2之间。 相似文献
85.
Most woody plants contain a diverse array of plant secondary metabolites (PSMs) that deter vertebrate herbivores. However,
mammalian folivores have evolved a complex of physiological and behavioural strategies to counter these compounds, leading
to the development of an “evolutionary arms race”. Marsupial folivores are ideal models to investigate the role of PSMs in
the interaction between the external foraging environment and the digestive physiology of mammalian herbivores, as we have
a very strong understanding of the diversity and modes of action of PSMs in Eucalyptus, as well as the mechanisms by which animals overcome the effects of these compounds. Studies of marsupial folivores have
benefited from the facts that: these herbivores subsist on relatively poor quality diets; they include feeding types from
specialist species such as the koala, to generalists; and life history factors such as maternal investment in reproduction
can be measured more easily than in eutherians. Here, we describe patterns of spatial variation in the types and distributions
of plant secondary metabolites in Australian forests and discuss how this variation influences foraging behaviour, habitat
selection and life history strategies in arboreal, folivorous marsupials. We also provide a summary of our understanding of
the mechanisms by which marsupials detect and regulate their intake of toxic compounds. While our examples are drawn largely
from studies of the interaction between marsupials and Eucalyptus, this knowledge is applicable to advancing our understanding of interactions in plant–mammal systems more broadly. We also
identify and discuss key areas that should be the focus of future research. 相似文献
86.
87.
88.
Ben Drake James C. R. Smart Mette Termansen Klaus Hubacek 《Regional Environmental Change》2013,13(3):649-659
Many regulating ecosystem services exhibit non-excludability and non-rivalry characteristics akin to public goods. This makes it unlikely that such regulating ecosystem services will attract a price in the marketplace. Policymakers, therefore, find difficulties in determining a correct economic valuation for regulating ecosystem services, with potentially severe consequences for aligning policy for ecosystem service provision with public preferences for service delivery. This research used a choice modelling approach to estimate public preferences for delivery of two regulating ecosystem services; reductions in the flood risk to the British city of York (implemented by filling in drainage ditches in peat moorland further up the catchment), and a reduction in CO2 emissions (implemented by planting Poplar trees for biomass either locally in the study area or elsewhere in the UK). The choice experiment presented respondents with options providing different levels of CO2 reduction, implemented locally or nationally, and different levels of flood risk reduction, at a range of different prices, with a tax as the payment vehicle. Subsequent analysis with latent class (LC) models showed considerable heterogeneity of preference among respondents, particularly with regard to the location of tree planting for CO2 reduction. One LC segment showed a significant preference for achieving a high level CO2 reduction through national, as opposed to local tree planting, potentially indicating the existence of NIMBYism. The same LC segment displayed a preference for moderate reductions in the flood risk to York, even though this would deliver no personal benefit for a substantial proportion of the segment. This could, therefore, indicate altruistic behaviour towards geographically proximate beneficiaries. 相似文献
89.
I. Ben TaloubaL. Balland N. Mouhab M.A. Abdelghani-Idrissi 《Journal of Loss Prevention in the Process Industries》2011,24(4):391-396
The thermal stability of organic peroxides (cumene hydroperoxide 80 wt% and dicumyl peroxide) was studied by means of calorimetric measurement (DSC, TA Q1000) in an isotherm mode and a dynamic mode. Analysis of power profiles released in the isothermal mode was combined with the analysis of the decomposed compounds by a gas chromatograph/mass spectrometer (GC/MS) to determine the reaction mechanisms corresponding to each of the two reactions. In this work, a methodology for estimating kinetic parameters was based on the comparison of the power profile (dynamic mode) given by the model to that obtained experimentally by changing the parameters values. Parameter estimation is achieved using the mixed estimation method where a genetic algorithm is combined with a locally convergent method. 相似文献
90.
Erin H. Gillam Gary F. McCracken John K. Westbrook Ya-Fu Lee Michael L. Jensen Ben B. Balsley 《Behavioral ecology and sociobiology》2009,64(1):69-79
Bats alter their echolocation in response to changes in ecological and behavioral conditions, but little is known about how
they adjust call structure in response to changes in altitude. We examined altitudinal variation in the echolocation of Brazilian
free-tailed bats, Tadarida brasiliensis, a species known to fly to altitudes of 3,000 m above the ground. From 50.2 h of recordings, we analyzed 113 high-quality
echolocation call sequences recorded from 0 to 862 m above ground level. Bats flying near the ground used shorter, higher-frequency,
broader-bandwidth calls compared to bats at higher altitudes, an effect likely due to the greater levels of echo-producing
clutter (i.e., vegetation, buildings) found near the ground. When ground-level recordings are excluded, bats continue to shift
towards the use of longer-duration, lower-frequency, narrower-bandwidth calls with increasing altitude. We propose that the
observed high-altitude changes in call structure are a response to changing acoustic attenuation rates and/or decreasing insect
densities at higher altitudes. 相似文献