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Aquatic Microbial Ecology

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AME 32:203-207 (2003)  -  doi:10.3354/ame032203

Nutritional quality of a freshwater heterotrophic flagellate: trophic upgrading of its microalgal diet for Daphnia hyalina

Alexandre Bec1,2,*, Christian Desvilettes1, Aurélie Véra1, Charles Lemarchand1, Dominique Fontvieille2, Gilles Bourdier1

1Laboratoire de Biologie des Protistes, UMR CNRS 6023, Université Blaise Pascal, 63177 Aubière cedex, France
2CARRTEL, Université de Savoie, 73376 Le Bourget du Lac cedex, France

ABSTRACT: Bacterivorous freshwater heterotrophic flagellates seem to be too poor in (n-3) series polyunsaturated fatty acids (PUFA) to be able to sustain major zooplankton growth by themselves. This study shows that when the heterotrophic flagellate Aulacomonas submarina fed on microalgae, either Rhodomonas lacustris (Aulacomonas/R.) or Chlorogonium elongatum (Aulacomonas/C.), this species exhibited (n-3) series PUFA in great quantities. Therefore, A. submarina PUFA composition seems to depend mainly on its algal diet. However, the biosynthetic capacities of A. submarina seem to have endowed it with greater amounts of 20 PUFA and a more diversified PUFA composition. Moreover, this study also shows that Daphnia hyalina exhibits a higher fecundity when fed on Aulacomonas/C. (or Aulacomonas/R.) than is the case when fed on C. elongatum (or respectively R. lacustris). This suggests that the ability of A. submarina to convert dietary lipids results in the biochemical value of its food source being upgraded.

KEY WORDS: Heterotrophic nanoflagellates · Nutritional quality · Fatty acids · PUFA

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