Original paper

Fatty acids as biomarkers to indicate main carbon sources of four major invertebrate families in a large River (the Allier, France)

Descroix, Aurélie; Bec, Alexandre; Bourdier, Gilles; Sargos, Denis; Sauvanet, Jeremy; Misson, Benjamin; Desvilettes, Christian


We used fatty acids (FA) as biomarkers to determine the principal sources of the organic matter assimilated by four families of aquatic insects (Baetidae, Chironomidae, Hydropsychidae and Simuliidae) prevailing in the macroinvertebrates assemblages observed in the riffle areas of a large temperate river (Allier, France). FA profiles extracted from different sources of organic matter (epilithic biofilm, benthic organic matter, fine suspended organic matter) and from each macroinvertebrate family were analyzed and compared. This has highlighted the importance of carbon from autochthonous primary production in the larvae diet. Despite different feeding modes and whatever the localization of the sites along the river continuum, the macroinvertebrates' lipids contained specific diatom markers. Moreover, the assimilation of autochthonous carbon seemed to increase in downstream riffles where macroinvertebrates tend to feed opportunistically on sestonic and/or benthic microalgae.


macroinvertebratesepilithic biofilmallochthonous and autochthonous organic matteraquatic food web