Diversity and stability of an estuarine trophic network

Type Article
Date 2008-04
Language English
Author(s) Lobry Jeremy1, David V2, Pasquaud S3, Lepage M3, Sautour B2, Rochard E3
Affiliation(s) 1 : IFREMER, Ctr Nantes, Dept EMH, F-44311 Nantes 3, France.
2 : Univ Bordeaux 1, CNRS, Lab Oceanog Biol, UMR 5805, F-33120 Arcachon, France.
3 : Cemagref, Grp Bordeaux, Unite Ecosyst Estuariens & Poissons Migrateurs Am, F-33612 Cestas, France.
Source Marine Ecology Progress Series (0171-8630) (Inter-Research), 2008-04 , Vol. 358 , P. 13-25
DOI 10.3354/meps07294
WOS© Times Cited 76
Keyword(s) Gironde estuary, Ecopath, Diversity, Stability, Network analysis, Food web, Estuarine ecosystem
Abstract Estuarine areas provide highly valuable ecosystem benefits for human populations, despite being under intense demographic, economic and ecological pressures. Hence, an understanding of the structure and function of estuarine ecosystems is essential for understanding the persistence and stability of these ecosystems and their response to perturbations. This study synthesises available data and knowledge about the Gironde estuary (SW France) in a mass-balanced trophic model to illustrate potential key patterns in the functioning of the estuarine ecosystem and key elements of its stability. In order to evaluate the total direct and indirect impact on the whole community of the 2 main sources of anthropogenic perturbations in the estuarine area, mortalities induced by fishing and the Blayais nuclear power plant were included in the model. The results suggest that in the Gironde, a typical heterotrophic estuary, there is an asymmetrical flow between distinct and complementary energy channels that enhances the stability of the food web. This dynamic process is illustrated by differential trophic flows in the water column according to the seasons. The succession of species in the environment indicates an optimisation of the use of the available carbon resources over a typical year by the estuarine biological communities. Finally, it seems that an increase in human impacts could significantly affect the topology and functioning of the food web by altering stabilizing elements of the network and decreasing the diversity of trophic flows that insures resilience of the trophic structure.
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