title: Seasonal effects of cadmium accumulation in periphytic diatom communities of freshwater biofilms.
abstract: The relationships between diatom species and cadmium (Cd) accumulated in biofilms of the Riou-Mort River (SW, France) were studied in July 2004 and March 2005. Biofilms were sampled from artificial substrates immersed along a metallic pollution gradient during 20 days. Dynamics of diatom communities and cadmium accumulation were followed by collecting samples after 4, 7, 14 and 20 days of biofilm colonization. Cd accumulation in biofilms during experiment was significantly higher in Cd polluted station (Joanis) than in reference station (Firmi) for both seasons. Periphytic diatom composition varied between sites and seasons. At Firmi station, seasonal dynamics of diatom communities were stable with the dominance of Cyclotella meneghiniana and Melosira varians in July and Surirellabrebissonnii and Navicula gregaria in March. At Joanis station, diatom communities mainly responded to high levels of metal by a high proportion of small, adnate species. Positive correlations between Eolimna minima, Nitzschia palea, Encyonema minutum, Surirella angusta, and Gomphonema parvulum and cadmium accumulation were observed, indicating that these species are tolerant to high levels of cadmium. On the other hand, negative correlations of C. meneghiniana, N. gregaria, Navicula lanceolata, M. varians and Nitzschia dissipata with cadmium qualify them as sensitive diatom species. Periphytic diatom composition through the presence of specific species highlight metal tolerant indicator diatom groups which will be meaningful for biomonitoring pollution in natural aquatic systems.
authors.affiliation: Institute of Environmental Technology, Vietnamese Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay, Hanoi, Vietnam. duongthuy0712@yahoo.com
authors.forename: Thi Thuy
authors.initials: TT
authors.lastname: Duong
authors.forename: Soizic
authors.initials: S
authors.lastname: Morin
authors.forename: Olivier
authors.initials: O
authors.lastname: Herlory
authors.forename: Agnès
authors.initials: A
authors.lastname: Feurtet-Mazel
authors.forename: Michel
authors.initials: M
authors.lastname: Coste
authors.forename: Alain
authors.initials: A
authors.lastname: Boudou
mesh_terms: D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002104:Cadmium / Q000493:pharmacokinetics*; D002105:Cadmium Poisoning / Q000378:metabolism*; D017377:Diatoms / Q000187:drug effects* / Q000378:metabolism* / Q000502:physiology; D054750:Ecotoxicology / Q000379:methods*; D007700:Kinetics; D025341:Principal Component Analysis; D012621:Seasons; D014874:Water Pollutants, Chemical / Q000493:pharmacokinetics* / Q000506:poisoning
chemical_list: D014874:Water Pollutants, Chemical; D002104:Cadmium