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341.
Julia Wohlers-Z?llner Antje Biermann Anja Engel Petra D?rge Aleksandra M. Lewandowska Markus von Scheibner Ulf Riebesell 《Marine Biology》2012,159(11):2503-2518
A comparative analysis of data, obtained during four indoor-mesocosm experiments with natural spring plankton communities from the Baltic Sea, was conducted to investigate whether biogeochemical cycling is affected by an increase in water temperature of up to 6?°C above present-day conditions. In all experiments, warming stimulated in particular heterotrophic bacterial processes and had an accelerating effect on the temporal development of phytoplankton blooms. This was also mirrored in the build-up and partitioning of organic matter between particulate and dissolved phases. Thus, warming increased both the magnitude and rate of dissolved organic carbon (DOC) build-up, whereas the accumulation of particulate organic carbon (POC) and phosphorus (POP) decreased with rising temperature. In concert, the observed temperature-mediated changes in biogeochemical components suggest strong shifts in the functioning of marine pelagic food webs and the ocean’s biological carbon pump, hence providing potential feedback mechanisms to Earth’s climate system. 相似文献
342.
Maximum species richness at intermediate frequencies of disturbance: consistency among levels of productivity 总被引:2,自引:0,他引:2
Development of a mechanistic understanding and predictions of patterns of biodiversity is a central theme in ecology. One of the most influential theories, the intermediate disturbance hypothesis (IDH), predicts maximum diversity at intermediate levels of disturbance frequency. The dynamic equilibrium model (DEM), an extension of the IDH, predicts that the level of productivity determines at what frequency of disturbance maximum diversity occurs. To test, and contrast, the predictions of these two models, a field experiment on marine hard-substratum assemblages was conducted with seven levels of disturbance frequency and three levels of nutrient availability. Consistent with the IDH, maximum diversity, measured as species richness, was observed at an intermediate frequency of disturbance. Despite documented effects on productivity, the relationship between disturbance and diversity was not altered by the nutrient treatments. Thus, in this system the DEM did not improve the understanding of patterns of diversity compared to the IDH. Furthermore, it is suggested that careful consideration of measurements and practical definitions of productivity in natural assemblages is necessary for a rigorous test of the DEM. 相似文献
343.
Alteration of steroidogenesis in H295R cells by organic sediment contaminants and relationships to other endocrine disrupting effects 总被引:1,自引:0,他引:1
Bláha L Hilscherová K Mazurová E Hecker M Jones PD Newsted JL Bradley PW Gracia T Duris Z Horká I Holoubek I Giesy JP 《Environment international》2006,32(6):749-757
A novel bioassay with the human adrenocortical carcinoma cell line H295R can be used to screen for endocrine disrupting chemicals that affect the expression of genes important in steroidogenesis. This assay was employed to study the effects of organic contaminants associated with the freshwater pond sediments collected in the Ostrava-Karvina region, Czech Republic. The modulation of ten major genes involved in the synthesis of steroid hormones (CYP11A, CYP11B2, CYP17, CYP19, 17betaHSD1, 17betaHSD4, CYP21, 3betaHSD2, HMGR, StAR) after exposure of H295R cells to sediment extracts was investigated using quantitative real-time polymerase chain reaction (PCR). Crude sediment extracts, containing high concentrations of polycyclic aromatic hydrocarbons (PAHs) and moderate amounts of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) significantly stimulated expression of the CYP11B2 gene (up to 10-fold induction), and suppressed expression of 3betaHSD2 and CYP21 genes. A similar pattern was observed with the extracts after treatment with concentrated sulfuric acid to remove labile chemicals (including PAHs) leaving only persistent PCBs, OCPs and potentially PCDD/Fs. Comparison of the results with other mechanistically based bioassays (arylhydrocarbon receptor, AhR, mediated responses in H4IIE-luc cells, and estrogen receptor mediated effects in MVLN cells) revealed significant endocrine disrupting potencies of organic contaminants present in the sediments (most likely antiestrogenicity). Pronounced effects were observed particularly in sediment extracts from the Pilnok Pond which harbors an unusual intersexual population of the narrow-cawed crayfish Pontastacus leptodactylus (Decapoda, Crustacea). This pilot study provided the first experimental evidence of the wider application of the H295R bioassay for screening complex environmental samples, and the results support the hypothesis of chemical-induced endocrine disruption in intersexual crayfish. 相似文献
344.
E. Tobias Krause Christoph Brummel Sarah Kohlwey Markus C. Baier Caroline Müller Francesco Bonadonna Barbara A. Caspers 《Behavioral ecology and sociobiology》2014,68(11):1819-1827
Although birds have recently been shown to possess olfactory abilities and to use chemical cues in communication, limited effort has been made to demonstrate the use of odorants in social contexts. Even less is known regarding the use of odorants in species recognition. The ability to recognize conspecifics should be more pronounced in social species. This study investigated the importance of olfactory cues in species recognition in females of two estrildid finch species with different levels of sociality. Combining odor preference tests with chemical analyses, we surveyed whether female zebra finches and diamond firetails are able to distinguish between the species based on volatile traits and whether individuals exhibit species-specific differences in body odorants. Zebra finches are more social than diamond firetails; nevertheless, both species have an overlapping distribution area. Applying an experimental Y-maze paradigm, we showed that zebra finches can use differences in their species odor fingerprints and displayed a significant preference for the odor of conspecifics over that of heterospecifics, whereas diamond firetails did not reveal a preference. Using gas chromatography and mass spectrometry, we demonstrated that body odorants of the two species were significantly different in relative composition. This finding demonstrates the potential importance of olfactory cues in species recognition, at least in social bird species. Even these two closely related species displayed remarkable differences in their responsiveness to similar chemical cues, which might be caused by species-specific differences in ecology, physiology, or evolution. 相似文献
345.
Doris Preininger Markus Boeckle Anita Freudmann Iris Starnberger Marc Sztatecsny Walter Hödl 《Behavioral ecology and sociobiology》2013,67(9):1449-1456
Many animals use multimodal (both visual and acoustic) components in courtship signals. The acoustic communication of anuran amphibians can be masked by the presence of environmental background noise, and multimodal displays may enhance receiver detection in complex acoustic environments. In the present study, we measured sound pressure levels of concurrently calling males of the Small Torrent Frog (Micrixalus saxicola) and used acoustic playbacks and an inflatable balloon mimicking a vocal sac to investigate male responses to controlled unimodal (acoustic) and multimodal (acoustic and visual) dynamic stimuli in the frogs’ natural habitat. Our results suggest that abiotic noise of the stream does not constrain signal detection, but males are faced with acoustic interference and masking from conspecific chorus noise. Multimodal stimuli elicited greater response from males and triggered significantly more visual signal responses than unimodal stimuli. We suggest that the vocal sac acts as a visual cue and improves detection and discrimination of acoustic signals by making them more salient to receivers amidst complex biotic background noise. 相似文献
346.
SUMMARY Sustainable development is a global challenge to science and society. In politics and economics the concepts for establishing a sustainable society are numerous, nonetheless necessary interdisciplinary approaches are still marginalised. Trying to foster a deeper communication between biology and social science, an evolutionary perspective on sustainable development is offered. Subsequently, the role of variability and diversity in evolution is highlighted. Hereby, special attention is devoted, among other things, to the links between variability and stability in the long term. Next, selection and variability are emphasised in the cultural context. This is followed by general implications for sustainability. In contrast to strategies aiming at short-term optimisation and economic efficiency, we argue that the conditions and circumstances maintaining variability and momentary sub-optimal alternatives are highly relevant for a socio-economic system that is heading for sustainable development. 相似文献
347.
Susanne Foitzik Ilka Maria Kureck Markus Hannes Rüger Dirk Metzler 《Behavioral ecology and sociobiology》2010,64(10):1641-1654
The ant Hypoponera opacior exhibits alternative reproductive morphs of males and females associated with distinct sexual behaviours. Our long-term study
reports strong seasonality in sexual production with a mating season in early and one in late summer. Winged (alate) reproductives
emerge in June, swarm during the monsoon season and establish new colonies independently. In contrast, wingless worker-like
(ergatoid) reproductives that appear in late August mate within their natal or adjacent nests and either do not disperse or
establish new nests close by. These divergent dispersal patterns allowed us to analyse the impact of local factors on investment
strategies by comparing sex allocation between and within the two reproductive events. The optimal sex ratio for ergatoid
reproductives should be influenced both by competition for matings between brothers (local mate competition) and rivalry among
young locally dispersing queens for workers, nest sites or food (local resource competition). The greater importance of local
resource competition was demonstrated both by a male-biased sex ratio for wingless sexuals and a stronger increase in the
number of males with total sexual production than for the number of queens. Microsatellite analysis revealed that inter-nest
variation in relatedness asymmetry cannot explain split sex ratios in the August generation. Instead, nests with related ergatoid
males raised a male-biased sex ratio contrary to the expectations under local mate competition. In conclusion, male bias in
wingless H. opacior indicates that local mate competition is less strong than local resource competition among ergatoid queens over the help
of workers during nest foundation. 相似文献
348.
Wybraniec S Schwartz L Wiesman Z Markus A Wolf D 《Journal of environmental science and health. Part. B》2002,37(3):235-245
The release characteristics of encapsulated formulations containing a combination of plant growth factors (PGF)--plant hormones (IBA, paclobutrazol), nutrients (fertilizers, microelements), and fungicide (prochloraz)--were studied. The formulations were prepared by encapsulating the active ingredients in a polyethylene matrix and, in some cases, subsequently coating the product with polyurethane. Dissolution experiments were carried out with both coated and non-coated formulations to determine the sustained release patterns of the active ingredients. The PGF controlled-release systems obtained have been shown to promote development of root systems, vegetative growth, and reproductive development in cuttings, potted plants, or garden plants of various plant species. These beneficial effects are attributable to the lasting and balanced PGF availability provided by these systems. 相似文献
349.
Incorporating soil structure and root distribution into plant uptake models for radionuclides: toward a more physically based transfer model 总被引:1,自引:0,他引:1
Albrecht A Schultze U Liedgens M Flühler H Frossard E 《Journal of environmental radioactivity》2002,59(3):329-350
Most biosphere and contamination assessment models are based on uniform soil conditions, since single coefficients are used to describe the transfer of contaminants to the plant. Indeed, physical and chemical characteristics and root distribution are highly variable in the soil profile. These parameters have to be considered in the formulation of a more realistic soil-plant transfer model for naturally structured soils. The impact of monolith soil structure (repacked and structured) on Zn and Mn uptake by wheat was studied in a controlled tracer application (dye and radioactive) experiment. We used Brilliant Blue and Sulforhodamine B to dye flow lines and 65Zn and 54Mn to trace soil distribution and plant uptake of surface-applied particle-reactive contaminants. Spatial variation of the soil water content during irrigation and plant growth informs indirectly about tracer and root location in the soil profile. In the structured monolith, a till pan at a depth of 30 cm limited vertical water flow and root penetration into deeper soil layers and restricted tracers to the upper third of the monolith. In the repacked monolith, roots were observed at all depths and fingering flow allowed for the fast appearance of all tracers in the outflow. These differences between the two monoliths are reflected by significantly higher 54Mn and 65Zn uptake in wheat grown on the structured monolith. The higher uptake of Mn can be modelled on the basis of radionuclide and root distribution as a function of depth and using a combination of preferential flow and rooting. The considerably higher uptake of Zn requires transfer factors which account for variable biochemical uptake as a function of location. 相似文献
350.
Germany seems to be one of the leading nations in solid waste management, especially in the case of packaging waste; success
stories about the ongoing increase in recycling strengthen this impression. However, enormous costs and questionable ecological
benefits are the result of Germany's packaging ordinance and the formation of the recycling organization Duales System Deutschland
(DSD). This article shows that similar progress in the reduction and recycling of packaging could have been realized without
the packaging ordinance and dual system, with lower costs. This regulatory impact analysis of the German packaging ordinance
covers all the effects on the different life-cycle stages of packaging, from production to recycling or disposal. The conclusion
is that a fragmentary solid waste management approach – one that is based, like the German packaging ordinance, more on ideology
than on facts – leads to enormous costs and questionable ecological benefits. To improve this situation, there is a need for
an integrated solid waste management approach, based on evaluation of the economic, environmental, and social effects of different
waste management options for the materials involved.
Received: February 4, 1999 / Accepted: April 30, 1999 相似文献