共查询到20条相似文献,搜索用时 31 毫秒
1.
Andria K. Salas 《Ecological modelling》2011,222(5):1192-1204
Indirect effects are powerful influences in ecosystems that may maintain species diversity and alter apparent relationships between species in surprising ways. Here, we applied network environ analysis to 50 empirically-based trophic ecosystem models to test the hypothesis that indirect flows dominate direct flows in ecosystem networks. Further, we used Monte Carlo based perturbations to investigate the robustness of these results to potential error in the underlying data. To explain our findings, we further investigated the importance of the microbial food web in recycling energy-matter using components of the Finn Cycling Index and analysis of environ centrality. We found that indirect flows dominate direct flows in 37/50 (74.0%) models. This increases to 31/35 (88.5%) models when we consider only models that have cycling structure and a representation of the microbial food web. The uncertainty analysis reveals that there is less error in the I/D values than the ±5% error introduced into the models, suggesting the results are robust to uncertainty. Our results show that the microbial food web mediates a substantial percentage of cycling in some systems (median = 30.2%), but its role is highly variable in these models, in agreement with the literature. Our results, combined with previous work, strongly suggest that indirect effects are dominant components of activity in ecosystems. 相似文献
2.
基于高通量定量PCR研究城市化小流域微生物污染特征 总被引:2,自引:0,他引:2
水体微生物污染(包括致病菌、病毒、寄生虫)会引起多种传染病和寄生虫病,对生产生活用水安全和人体健康造成重要威胁。本研究应用基于Taq Man探针的高通量荧光定量PCR技术对厦门市后溪流域冬季微生物污染进行检测,包含了5种粪便污染源(人源、反刍动物源、猪源、家禽源、狗源)微生物源示踪分子标记物与12种病原微生物。结果表明,该流域在上游及水库5个位点没有粪便污染,仅在其中一个水库位点检测出棘阿米巴,微生物污染极小;中下游检测出人类、反刍动物、猪、家禽、狗粪便污染,并且检测出产气荚膜梭菌、肠聚集性大肠杆菌、肠毒素型大肠杆菌、幽门螺杆菌、霍乱弧菌、副溶血弧菌、棘阿米巴、克雷伯氏肺炎杆菌等病原菌,其中流经旧城区居民生活生产区水样微生物污染严重,下游新城区微生物污染较小。这些结果暗示着城市人类活动是流域微生物污染主要来源,应从污染源头加强微生物污染控制。 相似文献
3.
Silvana Vanucci 《Chemistry and Ecology》2003,19(4):299-320
Temporal changes in abundance and biomass of picophytoplankton, heterotrophic pico-eukaryotes, and nanoplankton assemblages were investigated along a transect crossing the Adriatic Sea, from the Italian to the Croatian coast. This 15-months (June 1999-August 2000) investigation allowed comparing microbial parameters during summer 1999 (year without mucilage) and summer 2000 when a major mucilage event occurred. Pico- and nanoplankton assemblages displayed significant differences between the 2 summer periods. The main differences can be summarized as: (i) presence of cyanobacterial blooms (up to 108 cells l-1) in summer 2000, absent in summer 1999; (ii) an increasing fraction of heterotrophic pico-eukaryotes (up to 5.0 × 106 cells l-1) and heterotrophic nanoplankton (size 2-5 µm) during mucilage event; (iii) a reduced abundance of small-sized (2-3 µm) phototrophic nanoplankton in summer 2000. Changes in community structure were signals of changes in trophic condition of the system, which resulted in a competitive advantage for small sized pico- and nanoheterotrophs. Data presented here indicated that mucilage events are associated with changes in microbial community structure and functioning in ambient water and induced the amplification of 3-step microbial food chain. The potential use of the heterotrophic pico-eukaryotes for describing alterations of the trophic pathways during mucilage events is discussed. 相似文献
4.
Kijune Sung Jaisoo Kim C.L. Munster M. Yavuz Corapcioglu Soyoung Park M.C. Drew Y.Y. Chang 《Ecological modelling》2006,190(3-4):277-286
Microorganisms make an important contribution to the degradation of contaminants in bioremediation as well as in phytoremediation. An accurate estimation of microbial concentrations in the soil would be valuable in predicting contaminant dissipation during various bioremediation processes. A simple modeling approach to quantify the microbial biomass in the rhizosphere was developed in this study. Experiments were conducted using field column lysimeters planted with Eastern gamagrass. The microbial biomass concentrations from the rhizosphere soil, bulk soil, and unplanted soil were monitored for six months using an incubation–fumigation method. The proposed model was applied to the field microbial biomass data and good correlation between simulated and experimental data was achieved. The results indicate that plants increase microbial concentrations in the soil by providing root exudates as growth substrates for microorganisms. Since plant roots are initially small and do not produce large quantities of exudates when first seeded, the addition of exogenous substrates may be needed to increase initial microbial concentrations at the start of phytoremediation projects. 相似文献
5.
Yanqing Duan Aijuan Zhou Xiuping Yue Zhichun Zhang Yanjuan Gao Yanhong Luo Xiao Zhang 《Frontiers of Environmental Science & Engineering》2021,15(1):12
6.
Ying Xue Keke Xiao Xiang Wu Mei Sun Yifei Liu Bei Ou Jiakuan Yang 《Frontiers of Environmental Science & Engineering》2023,17(3):35
7.
Yuhan Zheng Zhiguo Su Tianjiao Dai Feifei Li Bei Huang Qinglin Mu Chuanping Feng Donghui Wen 《Frontiers of Environmental Science & Engineering》2019,13(6):90
8.
Nan Yang Linqiong Wang Li Lin Yi Li Wenlong Zhang Lihua Niu Huanjun Zhang Longfei Wang 《Frontiers of Environmental Science & Engineering》2022,16(4):50
9.
Qinqin Liu Miao Li Rui Liu Quan Zhang Di Wu Danni Zhu Xuhui Shen Chuanping Feng Fawang Zhang Xiang Liu 《Frontiers of Environmental Science & Engineering》2019,13(2):28
10.
Tao Ya Zhimin Wang Junyu Liu Minglu Zhang Lili Zhang Xiaojing Liu Yuan Li Xiaohui Wang 《Frontiers of Environmental Science & Engineering》2023,17(5):60
11.
Anna Gras Marta GinovartJoaquim Valls Philippe C. Baveye 《Ecological modelling》2011,222(12):1998-2010
The fate of soil carbon and nitrogen compounds in soils in response to climate change is currently the object of significant research. In particular, there is much interest in the development of a new generation of micro-scale models of soil ecosystems processes. Crucial to the elaboration of such models is the ability to describe the growth and metabolism of small numbers of individual microorganisms, distributed in a highly heterogeneous environment. In this context, the key objective of the research described in this article was to further develop an individual-based soil organic matter model, INDISIM-SOM, first proposed a few years ago, and to assess its performance with a broader experimental data set than previously considered. INDISIM-SOM models the dynamics and evolution of carbon and nitrogen associated with organic matter in soils. The model involves a number of state variables and parameters related to soil organic matter and microbial activity, including growth and decay of microbial biomass, temporal evolutions of easily hydrolysable N, mineral N in ammonium and nitrate, CO2 and O2. The present article concentrates on the biotic components of the model. Simulation results demonstrate that the model can be calibrated to provide good fit to experimental data from laboratory incubation experiments performed on three different types of Mediterranean soils. In addition, analysis of the sensitivity toward its biotic parameters shows that the model is far more sensitive to some parameters, i.e., the microbial maintenance energy and the probability of random microbial death, than to others. These results suggest that, in the future, research should focus on securing better measurements of these parameters, on environmental determinants of the switch from active to dormant states, and on the causes of random cell death in soil ecosystems. 相似文献
12.
Kun Li Tingming Ye Wang Zhang Jianfeng Peng Yaohui Bai Weixiao Qi Huijuan Liu 《Frontiers of Environmental Science & Engineering》2022,16(2):17
13.
Yanli Lei Karen Stumm Nils Volkenborn Stephen A. Wickham Ulrike-G. Berninger 《Marine Biology》2010,157(6):1271-1282
The benthic microbial food web can be responsible for a large proportion of benthic carbon cycling yet there are few data
on the trophic interactions between this food web and macrobenthos. A large-scale field experiment was conducted to investigate
effects of eliminating the polychaete Arenicola marina on benthic microbes (prokaryotes, heterotrophic and autotrophic protists) and metazoan meiofauna in a marine intertidal flat
of the North Sea, Germany. Over a period of 2 years, quantity and composition of micro- and meiobenthos from unmanipulated
sites were compared to those from sites deplete of lugworms. These grazer treatments were cross-classified with different
sediment characteristics (low- and mid-intertidal areas). Lugworm removal resulted in an initial increase in abundance of
prokaryotes and nanoflagellates, which became less pronounced in the second year. Ciliates were not affected quantitatively,
but in the absence of lugworms, diversity and the proportion of carnivorous forms increased. Meiobenthos (nematodes, ostracods
and copepods) were affected only moderately. The observed changes are probably due to a combination of release from grazing/predation
pressure, changes in the species composition of higher trophic levels (namely large polychaetes) and altered environmental
conditions (such as depth of the oxygenated layer and sediment grain size). Spatial differences between sites of different
tidal exposure/grain size appeared to be as large as temporal differences during the 2 years following the manipulation of
the system. We conclude that in intertidal sediments, indirect effects due to habitat transformation are as important as direct
biological interactions (grazing pressure and competition) for the dynamics of the benthic microbial food web. 相似文献
14.
Shuqin Liu Rui Wu Xi Yang Shuting Fang Zhangmin Xiang Shenghong Yang Gangfeng Ouyang 《Frontiers of Environmental Science & Engineering》2022,16(9):116
15.
16.
K. J. Flynn 《Chemistry and Ecology》1989,4(1):21-36
Nutrient limitation of phytoplankton growth in nature is a complex phenomenon. the timing of nutrient limitation is a product of matching of algal growth with abiotic and/or biotic events regenerating nutrients, and mismatching with predator activity. the extent of production is governed by the concentration of atomic constituents which, in turn, is a function of the rapidity and quantity of nutrient regeneration by heterotrophs. Excess phytoplankton production over heterotroph demand is lost from the euphotic zone by sinking and from the ecosphere by sedimentation. Phytoplankton growth is therefore always limited by the size and activity of the regenerative food web, either directly through predation, or indirectly by inadequate nutrient regeneration. the open water column is a habitat deplete environment for metazoa, incapable of supporting simultaneous high predator and prey densities. Because of the incompatibility of the temporal and spatial scales of microbial and metazoan processes, and the presence of micro-habitats which can support a full recycling food web on microbial scales, the microbial loop is an important component of euphotic zone ecology. the total marine ecosystem runs at a nutrient sufficient level with nutrient deplete and replete phases dependent on matching of production with predation throughout the food web and subject to abiotic events. Man's release of N and P into coastal waters, if coupled with an increased incidence of mismatch resulting from climatic variation induced by the “greenhouse effect”, could have catastrophic effects on marine ecosystems. 相似文献
17.
Cho ST Tsai SH Ravindran A Selvam A Yang SS 《Environmental geochemistry and health》2008,30(3):255-272
To investigate the seasonal variations of microbial ecology in grassland of Tatachia forest, soil properties, microbial populations,
microbial biomass, and 16S rDNA clone library analysis were determined. The soil had temperatures 6.6–18.4°C, pH 3.6–5.1,
total organic carbon 1.11–10.68%, total nitrogen 0.18–0.78%, and C/N ratios 3.46–20.55. Each gram of dry soil contained bacteria,
actinomycetes, fungi, cellulolytic, phosphate-solubilizing microbes, and nitrogen-fixing microbes 4.54 × 104 to 3.79 × 107, 3.43 × 102 to 2.17 × 105, 5.74 × 103 to 3.76 × 106, 1.97 × 103 to 1.34 × 106, 8.49 × 102 to 5.59 × 105, and 3.86 × 102 to 3.75 × 105 CFU, respectively. Each gram of soil contained 117–2,482 μg of microbial biomass carbon, 23–216 μg of microbial biomass nitrogen
and 9–29 μg of DNA. The microbial populations, microbial biomass, and DNA decreased stepwise with the depth of soil, and they
had low values in winter seasons. The microbial populations, microbial biomass carbon, microbial biomass nitrogen, and DNA
at the BW2 horizon were 8.42–17.84, 19.26–64.40, 16.84–61.11, and 31.03–46.26% of those at the O horizon, respectively. When
analyzing 16S rDNA library, members of Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes,
candidate division TM1, candidate division TM7, Gammatimonadetes, and Verrucomicrobia were identified. Members of Proteobacteria
(44.4%) and Acidobacteria (33.3%) dominated the clone libraries. Within the phylum Proteobacteria, α-, β-, and γ-Proteobacteria
were most numerous, followed by δ-Proteobacteria. 相似文献
18.
The main principle of the economic approach to a trophic system we propose here lies in assuming that there is a transfer of food along a path between a prey and a predator if, for the predator, the benefits are greater than costs of predation on this path. Conversely, if the costs exceed the benefits, there are no flows. This trade-off, considered all along the food chains of an ecosystem, together with ecological processes (assimilation, somatic maintenance) results in a model coupling mass balance equations (biological constraints) and complementarity principles (Walras’ law). Here is the core of the Network Economics Approach to Trophic Systems (NEATS). 相似文献
19.
As the world's freshwater resources and available energy are alarmingly decreasing, the bioelectrochemical system (BES) is a cutting-edge technology for the resolution of the resource and energy issue. Researchers have paid much attention to t he application of t he BES configuration. Based on t he brief i ntroduction of m icrobial f uel cell a nd m icrobial electrolytic cell structure, principles, and domestic and foreign research, the BES and its influencing factors are introduced, specifically including: microbial activity, electrode materials, and configuration. Three important aspects (i.e., the electrode chamber, the reaction chamber, and micro-sensor) are summarized, and the advantages and disadvantages of single-electrode and multi-electrode chambers are compared, based on the microbial desalination cell. Microbial electrolysis desalination cell: Microbial electrolysis desalination and chemical-production cell have been discussed to introduce increasing reaction chamber configuration; this review focuses on the research of BES monitoring with regards to biochemical oxygen demand. The potential applications of the research progress are explored. The results show that the configuration of multi-chamber microbial fuel cell is complex and its efficiency is low, while the single chamber configuration is advantageous. The reaction chamber added is mainly aimed at desalination, and the study of the desalination pool still needs to be focused on optimizing the cation exchange membrane to maintain the anode pH balance and reduce the air cathode dissolved oxygen. Microbial electrode sensor can be applied in more areas, and its sensitivity and long-term stability need to be further improved. However, there is relatively less research on the abundance and activity of electricigen communities; the configurations and scopes of application of BES are still the research priority. © 2018 Science Press. All rights reserved. 相似文献
20.
Olivier Monga Mamadou Bousso Patricia Garnier Valrie Pot 《Ecological modelling》2008,216(3-4):291-302
During the past 10 years, soil scientists have started to use 3D Computed Tomography in order to gain a clearer understanding of the geometry of soil structure and its relationships with soil properties. We propose a geometric model for the 3D representation of pore space and a practical method for its computation. Our basic idea consists in representing pore space using a minimal set of maximal balls (Delaunay spheres) recovering the shape skeleton. In this representation, each ball could be considered as a maximal local cavity corresponding to the “intuitive” notion of a pore as described in the literature. The space segmentation induced by the network of balls (pores) was then used to spatialize biological dynamics. Organic matter and microbial decomposers were distributed within the balls (pores). A valuated graph representing the pore network, organic matter and distribution of micro-organisms was then defined. Microbial soil organic matter decomposition was simulated by updating this valuated graph. The method was implemented and tested using real CT images. The model produced realistic simulated results when compared with data in the literature in terms of the water retention curve and carbon mineralization. A decrease in water pressure decreased carbon mineralization, which is also in accordance with findings in the literature. From our results we showed that the influence of water pressure on decomposition is a function of organic matter distribution in the pore space. As far as we know, this is the approach to have linked pore space geometry and biological dynamics in a formal way. Our next goal will be to compare the model with experimental data of decomposition using different soil structures, and to define geometric typologies of pore space shape that can be attached to specific biological and dynamic properties. 相似文献