title: The response of epiphytic bacteria on Vallisneria natans (Lour.) Hara (Hydrocharitaceae) to increasing nutrient loadings.
abstract: To investigate the effects of water column nutrient loading on epiphytic bacteria, we determined the abundance and community composition of epiphytic bacteria on the submerged macrophyte Vallisneria natans (Lour.) Hara during the growth season (June-October) under four different nutrient concentrations (nitrogen (N)-phosphorus (P) in mg L(-1) : 0.5-0.05, 1.0-0.1, 5.0-0.5, 10.0-1.0; hereafter NP-1, NP-2, NP-3, NP-4, respectively), using epifluorescence microscopy method and terminal restriction fragment length polymorphism (T-RFLP) analysis, respectively. Relative to low nutrient conditions (NP-1), there was no significant effect on the epiphytic bacterial community, and even a decrease in the number of epiphytic bacteria, which linked to the well growth status of host macrophytes at moderate nutrient conditions (NP-2). However, further nutrient enrichment induced significant increase in the abundance of epiphytic bacteria, and marked changes in the community structures of epiphytic bacteria. Furthermore, at high nutrient conditions, epiphytic bacterial communities varied widely temporally, and were not stable compared with those at the lower nutrient conditions. These results indicated that the effects of nutrient enrichment on epiphytic bacteria were nonlinear and dependent on the nutrient concentrations in the water.
authors.affiliation: Key Laboratory of Watershed Science and Health of Zhejiang Province, Wenzhou Medical University, Wenzhou, China.|State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, China.
authors.forename: Xianlei
authors.initials: X
authors.lastname: Cai
authors.affiliation: School of International Studies, Wenzhou Medical University, Wenzhou, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Yao
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, China.
authors.forename: Guang
authors.initials: G
authors.lastname: Gao
authors.affiliation: College of Forest Resources and Environment, Nanjing Forestry University, Nanjing, China.
authors.forename: Yinfeng
authors.initials: Y
authors.lastname: Xie
authors.affiliation: College of Forest Resources and Environment, Nanjing Forestry University, Nanjing, China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, China.
authors.forename: Xiangming
authors.initials: X
authors.lastname: Tang
mesh_terms: D001419:Bacteria / Q000254:growth & development* / Q000378:metabolism; D018533:Biomass; D017753:Ecosystem; D005068:Eutrophication; D031321:Hydrocharitaceae / Q000382:microbiology*; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D012150:Polymorphism, Restriction Fragment Length; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D010758:Phosphorus; D009584:Nitrogen
keywords: Bacteria; Epiphytic; Nutrient loading; Submerged macrophyte