MEPS 246:17-37 (2003)  -  doi:10.3354/meps246017

Numerical analysis of the food web of an intertidal mudflat ecosystem on the Atlantic coast of France

Delphine Leguerrier1, Nathalie Niquil1,*, Nicolas Boileau2, Jadwiga Rzeznik1,3,4, Pierre-Guy Sauriau5, Olivier Le Moine6, Cédric Bacher5

1Laboratoire de Biologie et Environnement Marins, EA 3168, Université de La Rochelle, Pôle Sciences et Technologie, avenue Michel Crépeau, 17042 La Rochelle Cedex 1, France
2Ligue pour la Protection des Oiseaux (LPO), Réserve Naturelle de Moëze-Oléron, Plaisance, 17708 Saint-Froult, France
3ESA 8044 CNRS-BIM, Muséum National d¹Histoire Naturelle, 57 rue Cuvier 75231 Paris, France
4University of Gdansk, Institute of Oceanography, Marine Biology and Ecology Department, Al. Pilsudskiego 46, 81-378 Gdynia, Poland
5Centre de Recherche sur les Ecosystèmes Marins et Aquacoles (CREMA/UMR10 CNRS-IFREMER), BP 5, 17137 L¹Houmeau, France
6Laboratoire Conchylicole Poitou-Charentes (LCPC), IFREMER, BP 133, 17390 La Tremblade, France
*Corresponding author. Email:

ABSTRACT: Food web modelling is an ideal way to describe ecosystems, because it accounts for the totality of the relationships between its various components. One difficulty of such an approach, however, lies in the lack of data and information about some ecological relationships, resulting in underdefined systems. Inverse analysis can serve to complete steady-state food webs where the number of direct flow measurements is insufficient relative to the actual number of flows. We applied this method to the intertidal mudflat ecosystem of Brouage (eastern Marennes-Oléron Bay, SW France) and estimated the annual average carbon flows between the compartments of a coupled benthic and pelagic trophic food web from primary producers (microphytobenthos and phytoplankton) to top predators (fish and birds). The resulting network was very sensitive to the primary production of the microphytobenthos which was the most important flow in the system. Sensitivity analyses demonstrated the need for additional data on the nekton, pelagic protozoa, and bacterial compartments. The resulting network showed high bacterial activity, but indices resulting from network analysis showed low cycling in comparison with other ecosystems. The meiofauna had a small biomass, but constituted a very active compartment compared to the macrofauna. Bird production was limited by macrofaunal production. Macrofaunal production reached the maximum allowed by the analysis. The intertidal mudflat ecosystem at Brouage is dominated by benthic production (including benthic primary producers, secondary producers, and predators) with an input of phytoplankton primary production.

KEY WORDS: Carbon flow · Inverse analysis · Food web · Network analysis

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