LIttoral ENvironnement et Sociétés (LIENSs) - UMR 7266

benthic meiofauna

Thierry Guyot — 2021-01-04T10:22:36Z

BENTHIC MEIOFAUNA :

Meiofauna consist of microscopically small, motile animals (size ranging from 44 to 500 µm) occurring in and on soft substrates of both marine and freshwater ecosystems. They are known for their high abundance within coastal ecosystems. Nematodes generally dominate meiofauna communities in coastal intertidal ecosystems, often followed by benthic copepods as the second most abundant group. Nematodes occur from polar to tropical regions and from sandy beaches to deep-sea sediments. Their abundance is very high in intertidal soft-bottom coastal ecosystems, however this abundance can be quite variable (10⁵ to 10⁸ individuals.m^-2). Benthic copepods typically occur in habitats with medium-to-fine sand, where their abundance can be slightly higher than those of nematodes. Other groups of meiofauna, such as ostracods and polychaetes, are generally less abundant in soft-bottom intertidal habitats.

BENTHIC MEIOFAUNA STUDIED IN THE TEAM BIOFEEL :

Researchers from the team BIOFEEL mostly study two major groups of meiofauna : the nematodes, and the benthic copepods. Nematodes are characterized by four major feeding types, which biomass change depending on abiotic and biotic parameters : selective deposit feeders (which mostly rely on bacteria), non-selective deposit feeders, epigrowh feeders (which mostly rely on benthic microalgae, particularly diatoms) and omnivores/carnivores. Species from these different groups can be identified using the shape of their mouth, as this shape is closely related to their feeding behavior. Benthic copepods are generally dominated by harpacticoid and cyclopoid copepods. If nematodes can migrate into the sediment, copepods very mostly occur in the very first mm of the sediment.

RESEARCH CARRIED OUT IN THE TEAM BIOFEEL ABOUT BENTHIC MEIOFAUNA :

Determination of the food resources used by nematodes and benthic copepods using trophic markers (stable isotopes, fatty acids).
Determination of community structure of nematode assemblages.

RESEARCHERS FROM THE TEAM BIOFEEL WORKING ON BENTHIC MEIOFAUNA :

Christine Dupuy
Denis Fichet
Benoit Lebreton
Luuk van der Heijden

REFERENCE PUBLICATIONS :

Giere O., 2009. Meiobenthology. The microscopic fauna in aquatic sediments. Springer-Verlag, Berlin, 328 p.
Heip C., Vincx M., Vranken G., 1985. The ecology of marine nematodes. Oceanography and Marine Biology. An Annual Review 23, 399-489.
Hicks G.R.F., Coull B.C., 1983. The ecology of marine meiobenthic harpacticoid copepods. Oceanography and Marine Biology. An Annual Review 21, 67-175.
Moens T., Bergtold M., Traunspurger W., 2006. Feeding ecology of free-living benthic nematodes. In : Freshwater nematodes : ecology and taxonomy. Abebe E., Andrassy I., Traunspurger W. (Eds.), Wallingford & Cambridge, USA, CABI Publishing : 105-131.

MAJOR PUBLICATIONS OF THE TEAM BIOFEEL :

Dupuy C., Nguyen Thanh H., Mizrahi D., Jourde J., Bréret M., Agogué H., Beaugeard L., Bocher P., 2015. Structure and functional characteristics of the meiofauna community in highly unstable intertidal mudbanks in Suriname and French Guiana (North Atlantic coast of South America). Continental Shelf Research 110, 39-47.
Lebreton B., Richard P., Galois R., Radenac G., Brahmia A., Colli G., Grouazel M., André C., Guillou G., Blanchard G.F., 2012. Food sources used by sediment meiofauna in an intertidal Zostera noltii seagrass bed : a seasonal stable isotope study. Marine Biology 159, 1537-1550.
Pascal P.-Y., Dupuy C., Richard P., Haubois A.-G., Niquil N., 2008. Influence of environment factors on bacterial ingestion rate of the deposit-feeder Hydrobia ulvae and comparison with meiofauna. Journal of Sea Research 60, 151-156.
Pascal P.-Y., Dupuy C., Richard P., Mallet C., Armynot du Chatelet E., Niquil N., 2009. Seasonal variation in consumption of benthic bacteria by meio- and macrofauna in an intertidal mudflat. Limnology and Oceanography 54, 1048-1059.
Rzeznik-Orignac J., Boucher G., Fichet D., Richard P., 2008. Stable isotope analysis of food source and trophic position of intertidal nematodes and copepods. Marine Ecology Progress Series 359, 145-150.
Rzeznik-Orignac J., Fichet D., Boucher G., 2003. Spatio-temporal structure of the nematode assemblages of the Brouage mudflat (Marennes Oléron, France). Estuarine, Coastal and Shelf Science 58, 77-88.
Rzeznik-Orignac J., Fichet D., Boucher G., 2004. Extracting massive numbers of nematodes from muddy marine deposits : efficiency and selectivity. Nematology 6, 605-616.
Van der Heijden L.H., Rzeznik-Orignac J., Asmus R.M., Fichet D., Bréret M., Kadel P., Beaugeard L., Asmus H., Lebreton B., 2018. How do food sources drive meiofauna community structure in soft-bottom coastal food webs ? Marine Biology 165, 166.

benthic microalgae

Thierry Guyot — 2021-01-04T10:15:21Z

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.

BENTHIC MICROALGAE STUDIED IN THE TEAM BIOFEEL :

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).

RESEARCH CARRIED OUT IN THE TEAM BIOFEEL ABOUT BENTHIC MICROALGAE :

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).

RESEARCHERS FROM THE TEAM BIOFEEL WORKING ON BENTHIC MICROALGAE :

Christine Dupuy
Vincent Le Fouest
Benoit Lebreton
Raphaël Savelli

REFERENCE PUBLICATIONS :

Blanchard G.F., 2006. Analyse conceptuelle du système de production primaire microphytobenthique des vasières intertidales. Océanis 32, 215-235.
Kromkamp J.C., de Brouwer J.F.C., Blanchard G.F., Forster R., Créach V., 2006. Functioning of microphytobenthos in estuaries. Royal Academy of Arts and Sciences, Amsterdam, 262 p.
MacIntyre H.L., Geider R.J., Miller D.C., 1996. Microphytobenthos : The ecological role of the "secret garden" of unvegetated, shallow-water marine habitats. I. Distribution, abundance and primary production. Estuaries 19, 186-201.
Miller D.C., Geider R.J., MacIntyre H.L., 1996. Microphytobenthos : The ecological role of the Secret Garden of unvegetated, shallow-water marine habitats. II. Role in sediment stability and shallow-water food webs. Estuaries 19, 202-212.
Round F.E., Crawford R.M., Mann D.G., 1990. The Diatoms : biology and morphology of the genera. Cambridge University Press, Cambridge, 747 p.

MAJOR PUBLICATIONS OF THE TEAM BIOFEEL :

Blanchard G.F., Guarini J.-M., Orvain F., Sauriau P.-G., 2001. Dynamic behaviour of benthic microalgal biomass in intertidal mudflats. Journal of Experimental Marine Biology and Ecology 264, 85-100.
Guarini J.-M., Blanchard G.F., Gros P., Gouleau D., Bacher C., 2000. Dynamic model of the short-term variability of microphytobenthic biomass on temperate intertidal mudflats. Marine Ecology Progress Series 195, 291-303.
Haubois A.-G., Sylvestre F., Guarini J.-M., Richard P., Blanchard G.F., 2005. Spatio-temporal structure of the epipelic diatom assemblage from an intertidal mudflat in Marennes-Oléron Bay, France. Estuarine, Coastal and Shelf Science 64, 385-394.
Herlory O., Guarini J.-M., Richard P., Blanchard G.F., 2004. Microstructure of microphytobenthic biofilm and its spatio-temporal dynamics in an intertidal mudflat (Aiguillon Bay, France). Marine Ecology Progress Series 282, 33-44.
Lebreton B., Richard P., Galois R., Radenac G., Pfléger C., Guillou G., Mornet F., Blanchard G.F., 2011. Trophic importance of diatoms in an intertidal Zostera noltii seagrass bed : Evidence from stable isotope and fatty acid analyses. Estuarine, Coastal and Shelf Science 92, 140-153.
Méléder V., Savelli R., Barnett A., Polsenaere P., Gernez P., Cugier P., Lerouxel A., Le Bris A., Dupuy C., Le Fouest V., Lavaud J., 2020. Mapping the intertidal microphytobenthos gross primary production, part I : Coupling multispectral remote sensing and physical modeling. Frontiers in Marine Science 7, 520.
Riera P., Richard P., 1996. Isotopic determination of food sources of Crassostrea gigas along a trophic gradient in the estuarine bay of Marennes-Oléron. Estuarine, Coastal and Shelf Science 42, 347-360.
Savelli R., Méléder V., Cugier P., Polsenaere P., Dupuy C., Lavaud J., Barnett A., Le Fouest V., 2020. Mapping the intertidal microphytobenthos gross Primary production, Part II : Merging remote sensing and physical-biological coupled modeling. Frontiers in Marine Science 7, 521
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.