benthic microalgae


Benthic microalgae are photosynthetic microorganisms growing in the sediment, contrarily to phytoplankton that develop in the water column. The microphytobenthos can consist of diatoms, cyanobacteria, Chlorophyceae and/or flagellates. Among the diatoms, which largely dominate in intertidal mudflats of the Atlantic coasts, two types can be observed : the epipelic diatoms, which are motile, and the epipsammic diatoms, which are generally smaller and stick to sediment grains with mucilaginous secretions. Epipsammic diatoms generally dominate in the sandy and mixed sediments, while epipelic diatoms dominate in pure mud. These epipelic diatoms migrate to the sediment surface during diurnal low tides to realize the photosynthesis. Thirty-seven species of diatoms have been identified on the Brouage mudflat, which is one of the largest mudflats in the Marennes-Oléron bay.


Most of the studies on benthic microalgae are carried out on intertidal bare mudflats, but some studies are also done on other soft-bottom coastal habitats, like seagrass beds, sandflats, and shallow subtidal embayments. Researchers from the team BIOFEEL focus their research on the primary production of benthic microalgae, especially on bare mudflats, by building models of primary production based on remote sensing. Another part of the studies aims at better assessing the role of the microphytobenthos as a food source for the meiofauna, the macrofauna, and for fish (i.e. mullets).


Quantification of primary production based on modelling.
Determination of the role of benthic microalgae as a food source in the functioning of intertidal and subtidal habitats using trophic markers (stable isotopes, fatty acids).


Christine Dupuy
Vincent Le Fouest
Benoit Lebreton
Raphaël Savelli


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  • van der Heijden L.H., Niquil N., Haraldsson M., Asmus R.M., Pacella S.R., Graeve M., Rzeznik-Orignac J., Asmus H., Saint-Béat B., Lebreton B., 2020. Quantitative food web modeling unravels the importance of the microphytobenthos-meiofauna pathway for a high trophic transfer by meiofauna in soft-bottom intertidal food webs. Ecological Modelling 430, 109129.
publie le lundi 4 janvier 2021