title: Longitudinal changes in microbial planktonic communities of a French river in relation to pesticide and nutrient inputs.
abstract: To determine the effects of anthropic activities on river planktonic microbial populations, monthly water samples were collected for 11 months from two sampling sites characterized by differing nutrient and pesticide levels. The difference in trophic level between the two stations was particularly pronounced from May to November. Total pesticide concentrations were notably higher at the downstream station from April to October with a clear predominance of herbicide residues, especially the glyphosate metabolite aminomethylphosphonic acid (AMPA). From spring, algal biomass and density were favored by the high orthophosphate concentrations recorded at the downstream location. However, isolated drops in algal biomass were recorded at this sampling station, suggesting an adverse effect of herbicides on algal communities. No major difference was observed in bacterial heterotrophic production, density, or activity (CTC reduction) between the two sampling stations. No major variation was detected using the fluorescent in situ hybridization (FISH) method, but shifts in bacterial community composition were recorded by PCR-TTGE analysis at the downstream station following high nutrient and pesticide inputs. However, outside the main anthropic pollution period, the water's chemical properties and planktonic microbial communities were very similar at the two sampling sites, suggesting a high recovery potential for this lotic system.
authors.affiliation: Laboratoire de Biologie des Protistes, Equipe "Ecotoxicologie Microbienne", UMR CNRS 6023, Université Blaise Pascal, 63177 Aubière cedex, France. pesce@lyon.cemagref.fr
authors.forename: Stéphane
authors.initials: S
authors.lastname: Pesce
authors.forename: Céline
authors.initials: C
authors.lastname: Fajon
authors.forename: Corinne
authors.initials: C
authors.lastname: Bardot
authors.forename: Frédérique
authors.initials: F
authors.lastname: Bonnemoy
authors.forename: Christophe
authors.initials: C
authors.lastname: Portelli
authors.forename: Jacques
authors.initials: J
authors.lastname: Bohatier
mesh_terms: D001419:Bacteria / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D044822:Biodiversity; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D004784:Environmental Monitoring; D056890:Eukaryota / Q000145:classification / Q000187:drug effects*; D005602:France; D005618:Fresh Water / Q000032:analysis* / Q000382:microbiology; D005798:Genes, Bacterial / Q000235:genetics; D017672:Nitrogen Compounds / Q000032:analysis; D010575:Pesticides / Q000032:analysis*; D010710:Phosphates / Q000032:analysis; D010839:Phytoplankton / Q000145:classification / Q000187:drug effects; D011156:Population Density; D025341:Principal Component Analysis; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012621:Seasons; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors; D014316:Tritium / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D017672:Nitrogen Compounds; D010575:Pesticides; D010710:Phosphates; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D014316:Tritium; D002734:Chlorophyll; D013936:Thymidine; D000077194:Chlorophyll A