title: Responses of Aquatic Bacteria to Terrestrial Runoff: Effects on Community Structure and Key Taxonomic Groups.
abstract: Organic fertilizer application is often touted as an economical and effective method to increase soil fertility. However, this amendment may increase dissolved organic carbon (DOC) runoff into downstream aquatic ecosystems and may consequently alter aquatic microbial community. We focused on understanding the effects of DOC runoff from soils amended with compost, vermicompost, or biochar on the aquatic microbial community of a tropical reservoir. Runoff collected from a series of rainfall simulations on soils amended with different organic fertilizers was incubated for 16 days in a series of 200 L mesocosms filled with water from a downstream reservoir. We applied 454 high throughput pyrosequencing for bacterial 16S rRNA genes to analyze microbial communities. After 16 days of incubation, the richness and evenness of the microbial communities present decreased in the mesocosms amended with any organic fertilizers, except for the evenness in the mesocosms amended with compost runoff. In contrast, they increased in the reservoir water control and soil-only amended mesocosms. Community structure was mainly affected by pH and DOC concentration. Compared to the autochthonous organic carbon produced during primary production, the addition of allochthonous DOC from these organic amendments seemed to exert a stronger effect on the communities over the period of incubation. While the Proteobacteria and Actinobacteria classes were positively associated with higher DOC concentration, the number of sequences representing key bacterial groups differed between mesocosms particularly between the biochar runoff addition and the compost or vermi-compost runoff additions. The genera of Propionibacterium spp. and Methylobacterium spp. were highly abundant in the compost runoff additions suggesting that they may represent sentinel species of complex organic carbon inputs. Overall, this work further underlines the importance of studying the off-site impacts of organic fertilizers as their impact on downstream aquatic systems is not negligible.
authors.affiliation: Ecologie Microbienne, INRA, UMR1418, CNRS, UMR5557, Université Lyon 1Villeurbanne, France; Department of Hydrobiology, Institute of Environmental Technology, Vietnam Academy of Science and TechnologyHanoi, Vietnam; iEES-Paris (IRD, Sorbonne Universités, UPMC Univ Paris 06, CNRS, INRA, UPEC, Université Paris Diderot)Paris, France.
authors.forename: Huong T
authors.initials: HT
authors.lastname: Le
authors.affiliation: Department of Hydrobiology, Institute of Environmental Technology, Vietnam Academy of Science and Technology Hanoi, Vietnam.
authors.forename: Cuong T
authors.initials: CT
authors.lastname: Ho
authors.affiliation: Laboratory of Analytical Science, Institute of Chemistry, Vietnam Academy of Science and Technology Hanoi, Vietnam.
authors.forename: Quan H
authors.initials: QH
authors.lastname: Trinh
authors.affiliation: Laboratory of Analytical Science, Institute of Chemistry, Vietnam Academy of Science and Technology Hanoi, Vietnam.
authors.forename: Duc A
authors.initials: DA
authors.lastname: Trinh
authors.affiliation: Laboratory of Analytical Science, Institute of Chemistry, Vietnam Academy of Science and Technology Hanoi, Vietnam.
authors.forename: Minh T N
authors.initials: MT
authors.lastname: Luu
authors.affiliation: Soils and Fertilizers Research Institute Hanoi, Vietnam.
authors.forename: Hai S
authors.initials: HS
authors.lastname: Tran
authors.affiliation: IRD, UMR 242, Institute of Ecology and Environmental Sciences - Paris, c/o Soils and Fertilizers Research InstituteHanoi, Vietnam; IRD, UMR 210 Eco&SolsMontpellier, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Orange
authors.affiliation: iEES-Paris (IRD, Sorbonne Universités, UPMC Univ Paris 06, CNRS, INRA, UPEC, Université Paris Diderot)Paris, France; IRD, UMR 242, Institute of Ecology and Environmental Sciences - Paris, c/o Soils and Fertilizers Research InstituteHanoi, Vietnam.
authors.forename: Jean L
authors.initials: JL
authors.lastname: Janeau
authors.affiliation: iEES-Paris (IRD, Sorbonne Universités, UPMC Univ Paris 06, CNRS, INRA, UPEC, Université Paris Diderot) Paris, France.
authors.forename: Asmaa
authors.initials: A
authors.lastname: Merroune
authors.affiliation: iEES-Paris (IRD, Sorbonne Universités, UPMC Univ Paris 06, CNRS, INRA, UPEC, Université Paris Diderot)Paris, France; IRD, UMR 242, Institute of Ecology and Environmental Sciences - Paris, c/o Soils and Fertilizers Research InstituteHanoi, Vietnam.
authors.forename: Emma
authors.initials: E
authors.lastname: Rochelle-Newall
authors.affiliation: Ecologie Microbienne, INRA, UMR1418, CNRS, UMR5557, Université Lyon 1 Villeurbanne, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Pommier
keywords: DOC; aquatic microbial community; biochar; compost; mesocosms