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Aquatic Microbial Ecology

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AME 49:281-291 (2007)  -  DOI:

Free-living nematodes affect oxygen turnover of artificial diatom biofilms

M. Mathieu1, J. Leflaive1, L. Ten-Hage1, R. de Wit2, E. Buffan-Dubau3,*

1Laboratoire d’Ecologie Fonctionnelle (ECOLAB), UMR 5245 CNRS/UPS/INPT, Université Paul Sabatier, bât. 4R3, 118 route de Narbonne, 31062 Toulouse Cedex 4, France
2UMR 5119 CNRS—Université Montpellier I—Ifremer ‘Ecosystèmes lagunaires’, Université Montpellier II, Case 093, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
3Laboratoire d’Ecologie Fonctionnelle (ECOLAB) UMR 5245 CNRS/UPS/INPT, Université Paul Sabatier, 29 Rue Jeanne Marvig, 31055 Toulouse Cedex 9, France
*Corresponding author. Email:

ABSTRACT: The aim of the present study was to examine the effects of biofilm-dwelling nematode activity on the oxygen turnover of cultured diatom biofilms. Oxygen microprofiles were simultaneously measured using the microelectrode technique in biofilms incubated with and without nematodes during short-term (24 h) and medium-term (6 d) experiments. During 24 h nycthemeral incubations, maximum oxygen concentrations and oxygen peak depths of microprofiles, as well as net oxygen production rates, were significantly higher in the diatom biofilms with nematodes. These effects might be dependent on the densities of nematodes. In the present study, significant effects were observed at nematode densities exceeding 100 ind. cm–2, but not at a density <50 ind. cm–2. During 6 d incubations, net oxygen production in the photic zone was significantly higher in biofilm containing meiofauna than in biofilms without meiofauna. The processes involved are discussed. The short-term experiment simulates a disturbance of a lotic diatom biofilm as would be induced by a sudden colonisation of nematode populations. The question remains whether a long-term occurrence of nematodes in the biofilm would also result in an increased productivity rate. A first indication of a persistent increase in net productivity related to the continuous presence of nematodes is provided by the 6 d incubation experiment.

KEY WORDS: Diatom biofilms · Nematodes · Oxygen microprofile · Microelectrode · Oxygen community metabolism · Net production rate · Grazing · Bioturbation

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Cite this article as: Mathieu M, Leflaive J, Ten-Hage L, de Wit R, Buffan-Dubau E (2007) Free-living nematodes affect oxygen turnover of artificial diatom biofilms. Aquat Microb Ecol 49:281-291.

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