title: Relative importance of nutrients and mortality factors on prokaryotic community composition in two lakes of different trophic status: microcosm experiments.
abstract: The effect of nutrient resources (N and P enrichment) and of different grazing communities on the prokaryotic community composition (PCC) was investigated in two freshwater ecosystems: Sep reservoir (oligomesotrophic) and lake Aydat (eutrophic). An experimental approach using microcosms was chosen, that allowed control of both predation levels, by size fractionation of predators, and resources, by nutrient amendments. Changes in PCC were monitored by fluorescent in situ hybridization (FISH) and terminal-restriction fragment length polymorphism (T-RFLP). The main mortality agents were (i) heterotrophic nanoflagellates and virus-like particles in Aydat and (ii) cladocerans in Sep. All the nutritional elements assayed (N-NO3, P-PO4 and N-NH4) together with prokaryotic production (PP) always accounted for a significant part of the variations in PCC. Overall, prokaryotic diversity was mainly explained by resources in Sep, by a comparable contribution of resources and mortality factors in lake Aydat and, to a lesser extent, by the combined action of both.
authors.affiliation: Laboratoire de Biologie des Protistes, Université Blaise Pascal, UMR CNRS 6023, 63177 Aubière, France.
authors.forename: Ludwig
authors.initials: L
authors.lastname: Jardillier
authors.forename: Delphine
authors.initials: D
authors.lastname: Boucher
authors.forename: Sébastien
authors.initials: S
authors.lastname: Personnic
authors.forename: Stéphan
authors.initials: S
authors.lastname: Jacquet
authors.forename: Aurélie
authors.initials: A
authors.lastname: Thénot
authors.forename: Denis
authors.initials: D
authors.lastname: Sargos
authors.forename: Christian
authors.initials: C
authors.lastname: Amblard
authors.forename: Didier
authors.initials: D
authors.lastname: Debroas
mesh_terms: D000818:Animals; D001105:Archaea / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D044822:Biodiversity; D019641:DNA, Archaeal / Q000032:analysis / Q000235:genetics; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D017753:Ecosystem; D020387:Food Chain; D005602:France; D005618:Fresh Water; D017404:In Situ Hybridization, Fluorescence; D007448:Invertebrates / Q000502:physiology; D009584:Nitrogen; D010758:Phosphorus; D012150:Polymorphism, Restriction Fragment Length; D011235:Predatory Behavior; D011387:Prokaryotic Cells / Q000145:classification* / Q000502:physiology; D014780:Viruses / Q000302:isolation & purification
chemical_list: D019641:DNA, Archaeal; D004269:DNA, Bacterial; D010758:Phosphorus; D009584:Nitrogen