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71.
72.
Christian Mulder Henri A. Den Hollander J. Arie Vonk Axel G. Rossberg Gerard A. J. M. Jagers op Akkerhuis Gregor W. Yeates 《Die Naturwissenschaften》2009,96(7):813-826
The large range of body-mass values of soil organisms provides a tool to assess the ecological organization of soil communities.
The goal of this paper is to identify graphical and quantitative indicators of soil community composition and ecosystem functioning,
and to illustrate their application to real soil food webs. The relationships between log-transformed mass and abundance of
soil organisms in 20 Dutch meadows and heathlands were investigated. Using principles of allometry, maximal use can be made
of ecological theory to build and explain food webs. The aggregate contribution of small invertebrates such as nematodes to
the entire community is high under low soil phosphorus content and causes shifts in the mass–abundance relationships and in
the trophic structures. We show for the first time that the average of the trophic link lengths is a reliable predictor for
assessing soil fertility responses. Ordered trophic link pairs suggest a self-organizing structure of food webs according
to resource availability and can predict environmental shifts in ecologically meaningful ways.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to all users. 相似文献
73.
74.
Tilman Floehr Björn Scholz-Starke Hongxia Xiao Josef Koch Lingling Wu Junli Hou Anja Wolf Axel Bergmann Kerstin Bluhm Xingzhong Yuan Martina Roß-Nickoll Andreas Schäffer Henner Hollert 《环境科学学报(英文版)》2015,38(12):63-82
Besides obvious benefits,the Three Gorges Dam's construction resulted in new pollution scenarios with the potentials to threaten the Three Gorges Reservoir(TGR) ecosystem.In order to record organic contamination,to find links to ecotoxicological impacts and to serve as reference for ensuing monitoring,several sites in the TGR area were screened applying the triad approach with additional lines-of-evidence as a holistic assessment method.Sediments and the benthic fish species Pelteobagrus vachellii were sampled in 2011 and 2012 to determine organic pollution levels,mutagenic potentials and genotoxic impacts.Two regional hot-spots near the cities of Chongqing and Kaixian were identified and further investigated in 2013.Only polycyclic aromatic hydrocarbons(PAHs) could be detected in sediments in 2011(165–1653 ng/g),emphasizing their roles as key pollutants of the area.Their ubiquity was confirmed at Chongqing(150–433 ng/g) and Kaixian(127–590 ng/g) in2013.Concentrations were comparable to other major Chinese and German rivers.However,the immense sediment influx suggested a deposition of 216–636 kg PAH/day(0.2–0.6 mg PAH/(m2·day)),indicating an ecotoxicological risk.PAH source analysis highlighted primary impacts of combustion sources on the more industrialized upper TGR section,whereas petrogenic sources dominated the mid-low section.Furthermore,sediment extracts from several sites exhibited significant activities of frameshift promutagens in the Ames fluctuation assay.Additionally,significant genotoxic impairments in erythrocytes of P.vachellii were detected(Chongqing/Kaixian),demonstrating the relevance of genotoxicity as animportant mode of action in the TGR's fish.PAHs,their derivatives and non-target compounds are considered as main causative agents. 相似文献
75.
Natasha A. Lloyd Laura M. Keating Alyssa J. Friesen Dylan M. Cole Jana M. McPherson H. Resit Akçakaya Axel Moehrenschlager 《Conservation biology》2023,37(3):e14051
Over 1 million species around the world are at risk of extinction, and conservation organizations have to decide where to invest their limited resources. Cost-effectiveness can be increased by leveraging funding opportunities and increasing collaborative partnerships to achieve shared conservation goals. We devised a structured decision-making framework to prioritize species’ conservation programs based on a cost–benefit analysis that takes collaborative opportunities into account in an examination of national and global conservation return on investment. Conservation benefit is determined by modifying the novel International Union for the Conservation of Nature Green Status for Species to provide an efficient, high-level measure that is comparable among species, even with limited information and time constraints. We applied this prioritization approach to the Wilder Institute/Calgary Zoo, Canada, a nonprofit organization seeking to increase the number of species it assists with conservation translocations. We sought to identify and prioritize additional species’ programs for which conservation translocation expertise and actions could make the most impact. Estimating the likelihood of cost-sharing potential enabled total program cost to be distinguished from costs specific to the organization. Comparing a benefit-to-cost ratio on different geographic scales allowed decision makers to weigh alternative options for investing in new species’ programs in a transparent and effective manner. Our innovative analysis aligns with general conservation planning frameworks and can be adapted for any organization. 相似文献
76.
Polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardants in air and seawater of the European Arctic 总被引:3,自引:0,他引:3
Möller A Xie Z Sturm R Ebinghaus R 《Environmental pollution (Barking, Essex : 1987)》2011,159(6):1577-1583
The spatial distribution of polybrominated diphenyl ethers (PBDEs) and several alternative non-PBDE, non-regulated brominated flame retardants (BFRs) in air and seawater and the air-seawater exchange was investigated in East Greenland Sea using high-volume air and water samples. Total PBDE concentrations (Ó10PBDEs) ranged from 0.09 to 1.8 pg m−3 in the atmosphere and from 0.03 to 0.64 pg L−1 in seawater. Two alternative BFRs, Hexabromobenzene (HBB) and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE), showed similar concentrations and spatial trends as PBDEs. The air-seawater gas exchange was dominated by deposition with fluxes up to −492 and −1044 pg m−2 day−1 for BDE-47 and DPTE, respectively. This study shows the first occurrence of HBB, DPTE and other alternative flame retardants (e.g., pentabromotoluene (PBT)) in the Arctic atmosphere and seawater indicating that they have a similar long-range atmospheric transport potential (LRAT) as the banned PBDEs. 相似文献
77.
Organic waste and municipal solid waste usually contain considerable amounts of different nitrogen compounds, which may inhibit anaerobic degradation processes and cause problems in the downstream and peripheral devices. This refers particularly to the different process stages of anaerobic digestion, to wastewater treatment, and to exhaust air treatment. Neither the knowledge about nitrogen problems nor the technologies for elimination of nitrogen compounds from the wastewater or the exhaust air of anaerobic digestion can be regarded as state-of-the-art. Most of the technologies in question have already been applied in other areas, but are barely tested for application in anaerobic digestion plants. The few performance data and experiences at hand were mainly derived from pilot and demonstration facilities. In this paper, the problem of nitrogen will be discussed in detail according to the separate problem fields based on the authors' experience, as well as on the basis of a review of the relevant literature. Furthermore, possible solutions will be proposed and the need for further research and development will be formulated. 相似文献
78.
Hybridization between animal species has long been regarded as unusual, but is meanwhile accepted as a widespread phenomenon.
Typically, sexual interactions among species are studied in secondary contact zones of closely related species (hybrid zones)
or between invasive and native species, whereas hybridization between sympatric congeners has received little attention. Here,
we present a study on the hybridization potential of two grasshopper species, Chorthippus parallelus and Chorthippus montanus, which occur sympatric in large parts of Eurasia. We performed a mate choice experiment with specimens from an area of local
parapatry in northwestern Germany. Most copulations were conspecific, but males of both species and females of C. parallelus were indiscriminate in their mate choice, while females of C. montanus clearly preferred conspecific males. Although these results suggest asymmetric introgression, a no-choice hybridization experiment
revealed that hybridization is possible in both directions. The hatching success of the hybrids was intermediate between the
parental species. Female hybrids showed no clear mate preferences, indicating that back crossing in both directions is possible
in principle, but the fertility of the hybrids and the fitness of the F2 generation remain unknown. Our study suggests that
hybridization between sympatric species might occur more often than assumed. It might affect the ecology and local distribution
of animals in a similar way as competition does. 相似文献
79.
Topi K. Lehtonen Bob B. M. Wong P. Andreas Svensson Axel Meyer 《Behavioral ecology and sociobiology》2011,65(4):613-619
In many taxa, parental strategies can vary among individuals. This is especially true in species with biparental care, with
males, more often than females, deserting their mates. While there is an abundance of theoretical predictions and empirical
data on factors inducing mate abandonment by males, much less is known about what consequences this may have on female behaviour,
particularly in the field and in non-avian systems. Here, we compared brood defence rate, behavioural defence types, and brood
success of solitary and paired females in two species of Neotropical cichlid fish in their natural habitat. In terms of the
rate of territorial aggression towards potential brood predators, solitary females were able to fully compensate in the absence
of a male but, in so doing, ended up maintaining smaller territories, which appeared to compromise offspring fitness in at
least one of the two species. Hence, our results suggest that even extensive quantitative compensation in parental effort
by solitary females may not be enough to ensure adequate qualitative compensation for the lack of male participation, highlighting
the importance of distinguishing between these two aspects of compensatory parental care. 相似文献
80.
Edward F. Shultz Axel Fehrenbacher Frank E. Pfefferkorn Michael R. Zinn Nicola J. Ferrier 《Journal of Manufacturing Processes》2013,15(1):25-33
In this paper a shared control strategy is presented that allows a skilled operator to identify irregularities that occur during robotic friction stir welding (FSW) and assist the robotic system in producing an appropriate response. Human operators are adept at identifying disturbances; however, the complexity of the friction stir welding process makes it difficult for the operator to respond. While examining the capabilities of shared control in friction stir welding, this paper focuses on responding to defects that are caused by a lack of workpiece material during butt welding, such as gaps. A compensation strategy is presented that combines the human operator's perceptual strengths with an automated procedure for adjustment of the process parameters (i.e. travel angle and plunge depth). Experiments comparing four control strategies are performed while welding 5083-H116 aluminum. Through our experiments we demonstrate that if the FSW control task is appropriately shared between the human operator and the computer control system, the weld quality (strength) can be improved (from 9 ksi to 31 ksi for a gap size of 2.5 mm) as compared with the nominal case in which no corrections are made. 相似文献