The Experts below are selected from a list of 33 Experts worldwide ranked by ideXlab platform
David C. Coleman - One of the best experts on this subject based on the ideXlab platform.
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the influence of enchytraeidae oligochaeta on the soil porosity of small microcosms
Geoderma, 1993Co-Authors: P C J Van Vliet, Larry T. West, Paul F Hendrix, David C. ColemanAbstract:Tunneling and Burrowing activities of soil Organisms affect structure and porosity of soils, but the role of enchytraeids as a soil Burrowing Organism is unclear. This study was initiated to evaluate the effect of enchytraeids on soil porosity in two soils with different texture and similar, low organic matter contents. In small microcosms, the Burrowing activities of Enchytraeus minutus were followed during a 51 day period. The microcosms consisted of two glass plates with a bottom of plaster of Paris and sides of Plexiglas. Sieved (<1 mm), enchytraeid-free soil was added between the glass plates and two litter placement treatments were simulated by the addition of rye to the surface or by incorporating it into the soil. The soil in the microcosms was wetted from the bottom through the capillary action of the plaster and soil. Twenty enchytraeids were added to the microcosms and every 17 days the distribution of pores was determined under a stereomicroscope by a point counting technique and with image analysis. At least 65% of the enchytraeids survived in the microcosms, and in the surface litter treatments, the population expanded. Enchytraeids increased porosity in the microcosms at 17 days. At later times the porosity of the microcosms decreased to levels below the starting values. This decrease in porosity was attributed to consolidation of the soils as a result of overburden pressure and destabilization of soil aggregates caused by the egestion of the soil by enchytraeids. Porosity estimates by image analysis were much lower than by point counting, but a strong correlation was found between the two.
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The influence of Enchytraeidae (Oligochaeta) on the soil porosity of small microcosms
Geoderma, 1993Co-Authors: P C J Van Vliet, Larry T. West, Paul F Hendrix, David C. ColemanAbstract:Tunneling and Burrowing activities of soil Organisms affect structure and porosity of soils, but the role of enchytraeids as a soil Burrowing Organism is unclear. This study was initiated to evaluate the effect of enchytraeids on soil porosity in two soils with different texture and similar, low organic matter contents. In small microcosms, the Burrowing activities of Enchytraeus minutus were followed during a 51 day period. The microcosms consisted of two glass plates with a bottom of plaster of Paris and sides of Plexiglas. Sieved (
P C J Van Vliet - One of the best experts on this subject based on the ideXlab platform.
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the influence of enchytraeidae oligochaeta on the soil porosity of small microcosms
Geoderma, 1993Co-Authors: P C J Van Vliet, Larry T. West, Paul F Hendrix, David C. ColemanAbstract:Tunneling and Burrowing activities of soil Organisms affect structure and porosity of soils, but the role of enchytraeids as a soil Burrowing Organism is unclear. This study was initiated to evaluate the effect of enchytraeids on soil porosity in two soils with different texture and similar, low organic matter contents. In small microcosms, the Burrowing activities of Enchytraeus minutus were followed during a 51 day period. The microcosms consisted of two glass plates with a bottom of plaster of Paris and sides of Plexiglas. Sieved (<1 mm), enchytraeid-free soil was added between the glass plates and two litter placement treatments were simulated by the addition of rye to the surface or by incorporating it into the soil. The soil in the microcosms was wetted from the bottom through the capillary action of the plaster and soil. Twenty enchytraeids were added to the microcosms and every 17 days the distribution of pores was determined under a stereomicroscope by a point counting technique and with image analysis. At least 65% of the enchytraeids survived in the microcosms, and in the surface litter treatments, the population expanded. Enchytraeids increased porosity in the microcosms at 17 days. At later times the porosity of the microcosms decreased to levels below the starting values. This decrease in porosity was attributed to consolidation of the soils as a result of overburden pressure and destabilization of soil aggregates caused by the egestion of the soil by enchytraeids. Porosity estimates by image analysis were much lower than by point counting, but a strong correlation was found between the two.
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The influence of Enchytraeidae (Oligochaeta) on the soil porosity of small microcosms
Geoderma, 1993Co-Authors: P C J Van Vliet, Larry T. West, Paul F Hendrix, David C. ColemanAbstract:Tunneling and Burrowing activities of soil Organisms affect structure and porosity of soils, but the role of enchytraeids as a soil Burrowing Organism is unclear. This study was initiated to evaluate the effect of enchytraeids on soil porosity in two soils with different texture and similar, low organic matter contents. In small microcosms, the Burrowing activities of Enchytraeus minutus were followed during a 51 day period. The microcosms consisted of two glass plates with a bottom of plaster of Paris and sides of Plexiglas. Sieved (
Fatima Mahdaoui - One of the best experts on this subject based on the ideXlab platform.
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Impact of Oil on Bacterial Community Structure in Bioturbated Sediments
2016Co-Authors: Magalie Stauffert, Cristiana Cravo-laureau, Ra Barantal, Franck Gilbert, Christine Cagnon, David Amouroux, Fatima Mahdaoui, Brice Bouyssiere, Georges Stora, Robert DuranAbstract:Oil spills threaten coastlines where biological processes supply essential ecosystem services. Therefore, it is crucial to understand how oil influences the microbial communities in sediments that play key roles in ecosystem functioning. Ecosystems such as sediments are characterized by intensive bioturbation due to Burrowing macrofauna that may modify the microbial metabolisms. It is thus essential to consider the bioturbation when determining the impact of oil on microbial communities. In this study, an experimental laboratory device maintaining pristine collected mudflat sediments in microcosms closer to true environmental conditions – with tidal cycles and natural seawater – was used to simulate an oil spill under bioturbation conditions. Different conditions were applied to the microcosms including an addition of: standardized oil (Blend Arabian Light crude oil, 25.6 mg.g21 wet sediment), the common Burrowing Organism Hediste (Nereis) diversicolor and both the oil and H. diversicolor. The addition of H. diversicolor and its associated bioturbation did not affect the removal of petroleum hydrocarbons. After 270 days, 60 % of hydrocarbons had been removed in all microcosms irrespective of the H. diversicolor addition. However, 16S-rRNA gene and 16S-cDNA T-RFLP and RT-PCR-amplicon librarie
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Impact of oil on bacterial community structure in bioturbated sediments
PLoS ONE, 2013Co-Authors: Magalie Stauffert, Cristiana Cravo-laureau, Franck Gilbert, Christine Cagnon, David Amouroux, Ronan Jezequel, Sandra Barantal, Philippe Cuny, Cécile Militon, Fatima MahdaouiAbstract:Oil spills threaten coastlines where biological processes supply essential ecosystem services. Therefore, it is crucial to understand how oil influences the microbial communities in sediments that play key roles in ecosystem functioning. Ecosystems such as sediments are characterized by intensive bioturbation due to Burrowing macrofauna that may modify the microbial metabolisms. It is thus essential to consider the bioturbation when determining the impact of oil on microbial communities. In this study, an experimental laboratory device maintaining pristine collected mudflat sediments in microcosms closer to true environmental conditions - with tidal cycles and natural seawater - was used to simulate an oil spill under bioturbation conditions. Different conditions were applied to the microcosms including an addition of: standardized oil (Blend Arabian Light crude oil, 25.6 mg.g21 wet sediment), the common Burrowing Organism Hediste (Nereis) diversicolor and both the oil and H. diversicolor. The addition of H. diversicolor and its associated bioturbation did not affect the removal of petroleum hydrocarbons. After 270 days, 60% of hydrocarbons had been removed in all microcosms irrespective of the H. diversicolor addition. However, 16S-rRNA gene and 16S-cDNA T-RFLP and RT-PCR-amplicon libraries analysis showed an effect of the condition on the bacterial community structure, composition, and dynamics, supported by PerMANOVA analysis. The 16S-cDNA libraries from microcosms where H. diversicolor was added (oiled and un-oiled) showed a marked dominance of sequences related to Gammaproteobacteria. However, in the oiled-library sequences associated to Deltaproteobacteria and Bacteroidetes were also highly represented. The 16S-cDNA libraries from oiled-microcosms (with and without H. diversicolor addition) revealed two distinct microbial communities characterized by different phylotypes associated to known hydrocarbonoclastic bacteria and dominated by Gammaproteobacteria and Deltaproteobacteria. In the oiled-microcosms, the addition of H. diversicolor reduced the phylotype-richness, sequences associated to Actinobacteria, Firmicutes and Plantomycetes were not detected. These observations highlight the influence of the bioturbation on the bacterial community structure without affecting the biodegradation capacities.
Larry T. West - One of the best experts on this subject based on the ideXlab platform.
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the influence of enchytraeidae oligochaeta on the soil porosity of small microcosms
Geoderma, 1993Co-Authors: P C J Van Vliet, Larry T. West, Paul F Hendrix, David C. ColemanAbstract:Tunneling and Burrowing activities of soil Organisms affect structure and porosity of soils, but the role of enchytraeids as a soil Burrowing Organism is unclear. This study was initiated to evaluate the effect of enchytraeids on soil porosity in two soils with different texture and similar, low organic matter contents. In small microcosms, the Burrowing activities of Enchytraeus minutus were followed during a 51 day period. The microcosms consisted of two glass plates with a bottom of plaster of Paris and sides of Plexiglas. Sieved (<1 mm), enchytraeid-free soil was added between the glass plates and two litter placement treatments were simulated by the addition of rye to the surface or by incorporating it into the soil. The soil in the microcosms was wetted from the bottom through the capillary action of the plaster and soil. Twenty enchytraeids were added to the microcosms and every 17 days the distribution of pores was determined under a stereomicroscope by a point counting technique and with image analysis. At least 65% of the enchytraeids survived in the microcosms, and in the surface litter treatments, the population expanded. Enchytraeids increased porosity in the microcosms at 17 days. At later times the porosity of the microcosms decreased to levels below the starting values. This decrease in porosity was attributed to consolidation of the soils as a result of overburden pressure and destabilization of soil aggregates caused by the egestion of the soil by enchytraeids. Porosity estimates by image analysis were much lower than by point counting, but a strong correlation was found between the two.
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The influence of Enchytraeidae (Oligochaeta) on the soil porosity of small microcosms
Geoderma, 1993Co-Authors: P C J Van Vliet, Larry T. West, Paul F Hendrix, David C. ColemanAbstract:Tunneling and Burrowing activities of soil Organisms affect structure and porosity of soils, but the role of enchytraeids as a soil Burrowing Organism is unclear. This study was initiated to evaluate the effect of enchytraeids on soil porosity in two soils with different texture and similar, low organic matter contents. In small microcosms, the Burrowing activities of Enchytraeus minutus were followed during a 51 day period. The microcosms consisted of two glass plates with a bottom of plaster of Paris and sides of Plexiglas. Sieved (
Paul F Hendrix - One of the best experts on this subject based on the ideXlab platform.
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the influence of enchytraeidae oligochaeta on the soil porosity of small microcosms
Geoderma, 1993Co-Authors: P C J Van Vliet, Larry T. West, Paul F Hendrix, David C. ColemanAbstract:Tunneling and Burrowing activities of soil Organisms affect structure and porosity of soils, but the role of enchytraeids as a soil Burrowing Organism is unclear. This study was initiated to evaluate the effect of enchytraeids on soil porosity in two soils with different texture and similar, low organic matter contents. In small microcosms, the Burrowing activities of Enchytraeus minutus were followed during a 51 day period. The microcosms consisted of two glass plates with a bottom of plaster of Paris and sides of Plexiglas. Sieved (<1 mm), enchytraeid-free soil was added between the glass plates and two litter placement treatments were simulated by the addition of rye to the surface or by incorporating it into the soil. The soil in the microcosms was wetted from the bottom through the capillary action of the plaster and soil. Twenty enchytraeids were added to the microcosms and every 17 days the distribution of pores was determined under a stereomicroscope by a point counting technique and with image analysis. At least 65% of the enchytraeids survived in the microcosms, and in the surface litter treatments, the population expanded. Enchytraeids increased porosity in the microcosms at 17 days. At later times the porosity of the microcosms decreased to levels below the starting values. This decrease in porosity was attributed to consolidation of the soils as a result of overburden pressure and destabilization of soil aggregates caused by the egestion of the soil by enchytraeids. Porosity estimates by image analysis were much lower than by point counting, but a strong correlation was found between the two.
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The influence of Enchytraeidae (Oligochaeta) on the soil porosity of small microcosms
Geoderma, 1993Co-Authors: P C J Van Vliet, Larry T. West, Paul F Hendrix, David C. ColemanAbstract:Tunneling and Burrowing activities of soil Organisms affect structure and porosity of soils, but the role of enchytraeids as a soil Burrowing Organism is unclear. This study was initiated to evaluate the effect of enchytraeids on soil porosity in two soils with different texture and similar, low organic matter contents. In small microcosms, the Burrowing activities of Enchytraeus minutus were followed during a 51 day period. The microcosms consisted of two glass plates with a bottom of plaster of Paris and sides of Plexiglas. Sieved (
