Search results for "microcosm"
showing 10 items of 102 documents
Short-term impact of biogas digestates on soils microbial communities
2022
International audience; Anaerobic digestion of organic waste is considered a key process to produce renewable energy to meet the growing sustainable energy demand. Digestates can be used in agriculture as soil amendments and improve crop yields. However, their use at large scale in agricultural fields still requires to prove their innocuity on soil biota, especially on microorganisms that play important roles in soil ecosystem. Here, we designed a microcosm experiment to compare the short-term (42-days) effects of four different digestates (derived from cattle manure, energy crop, food residues or slurry with bio-waste) on the soil microbial communities. Each digestate was applied on three …
Copper Dynamics and Impact on Microbial Communities in Soils of Variable Organic Status
2008
International audience; The effect of soil organic status on copper impact was investigated by means of a microcosm study carried out on a vineyard soil that had been amended with varying types of organic matter during a previous long-term field experiment. Soil microcosms were contaminated at 250 mg Cu kg−1 and incubated for 35 days. Copper distribution and dynamics were assessed in the solid matrix by a sequential extraction procedure and in the soil solution by measuring total and free exchangeable copper concentrations. Copper bioavailability was also measured with a whole-cell biosensor. Modifications of microbial communities were assessed by means of biomass-C measurements and charact…
Multiple stressors in Mediterranean coastal wetland ecosystems : Influence of salinity and an insecticide on zooplankton communities under different …
2021
Temperature increase, salinity intrusion and pesticide pollution have been suggested to be among the main stressors affecting the biodiversity of coastal wetland ecosystems. Here we assessed the single and combined effects of these stressors on zooplankton communities collected from a Mediterranean coastal lagoon. An indoor microcosm experiment was designed with temperature variation (20 °C and 30 °C), salinity (no addition, 2.5 g/L NaCl) and the insecticide chlorpyrifos (no addition, 1 μg/L) as treatments. The impact of these stressors was evaluated on water quality variables and on the zooplankton comunity (structure, diversity, abundance and taxa responses) for 28 days. This study shows …
Effect of carbon source supply and its location on competition between inoculated and established bacterial strains in sterile soil microcosm
1999
The aim of this work was to study how the location of a carbon source and of bacterial cells in soil can enhance the growth of a bacterial inoculum. Studies were performed using irradiated soil and two pairs of strains of Bradyrhizobium japonicum and Pseudomonas fluorescens. For each species, an antibiotic-resistant mutant was used as inoculant and introduced into a sterile soil pre-colonised with its parent strain. The inocula and a glycerol amendment were introduced together or separately into soil using porous microgranules or by spraying a suspension onto the bulk soil. Competition was assessed by plate counts of both inoculant and established populations. Both B. japonicum and P. fluor…
Submerged macrophytes as key players in aquatic ecosystems under global change: a multiscale experimental approach
2020
El actual cambio global está causando alteraciones en los ecosistemas de todo el mundo a través de cambios interactivos en los principales factores ambientales (e.g. la temperatura, la concentración de nutrientes y la radiación ultravioleta). Los ecosistemas acuáticos continentales son altamente vulnerables ante estos cambios y, específicamente, en la región mediterránea, la situación es peor ya que la mayoría de estos sistemas son someros y están expuestos a las perturbaciones ambientales y antrópicas. Las praderas de macrófitos sumergidos y, particularmente, los carófitos, son un elemento conspicuo de estos sistemas con un papel fundamental en su funcionamiento. Estos organismos proveen d…
Linking food webs to ecosystem processes: Piecewise linear models of soil microcosms
2008
Abstract A piecewise linear approach to link decomposer biomass and soil nitrogen dynamics is proposed. Dynamics of a detritus–fungus–nematode food chain were studied in a microcosm experiment and modelled to evaluate the role of fungal-feeding nematodes in N mineralization. The nematode dynamics switched from exponential growth to a resource-limited phase. At the same time the amount of ammonium nitrogen in soil started to increase, following an initial immobilization phase. Both nematode and ammonium dynamics could be described by two-phase linear equations. Two nitrogen models were compared. A model in which the nematode accounted for all mineralization could be fitted to the ammonium da…
Spatial distribution of ammonia-oxidizing bacteria and archaea across a 44-hectare farm related to ecosystem functioning
2011
Characterization of spatial patterns of functional microbial communities could facilitate the understanding of the relationships between the ecology of microbial communities, the biogeochemical processes they perform and the corresponding ecosystem functions. Because of the important role the ammonia-oxidizing bacteria (AOB) and archaea (AOA) have in nitrogen cycling and nitrate leaching, we explored the spatial distribution of their activity, abundance and community composition across a 44-ha large farm divided into an organic and an integrated farming system. The spatial patterns were mapped by geostatistical modeling and correlations to soil properties and ecosystem functioning in terms …
Environmental noise and population dynamics of the ciliated protozoa Tetrahymena thermophila in aquatic microcosms
2003
Population theory predicts that the reddened environmental noise, especially in combination with high population growth rate, reddens population dynamics, increases population variability and strengthens environment–population correlation. We tested these predictions with axenic populations of ciliated protozoa Tetrahymena thermophila. Populations with low and high growth rate were cultured in a stable environment, and in environments with sublethal temperature fluctuations that had blue, white and red spectra (i.e. negatively autocorrelated, uncorrelated, or positively autocorrelated, respectively). Population size and biomass of individuals were determined at 3-h intervals for 18 days. Dy…
Studies of root colonization by a microcosm community of arbuscular mycorrhizal fungi unsing nested PCR
1998
International audience
A microcosm study on the respiration and weight loss in birch litter and raw humus as influenced by soil fauna
1988
The effect of diverse soil fauna (Collembola, Acari, Enchytraeidae, Nematoda) on decomposition of dead organic matter was studied in microcosms containing (1) birch leaf litter, (2) raw humus of coniferous forest and (3) litter on humus. Total respiration (CO2 evolution) was monitored weekly, and mass loss, length of fungal hyphae (total and metabolically active) and survival of animal populations were checked at the end of weeks 12 and 21–22 from the start of experiment. Animal populations established themselves well during the incubation. At the end of the experiment some replicates containing litter had microarthropod densities of up to 500 specimens per microcosm, corresponding to a fie…