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- Title
European salt marshes diversity and functioning: The case study of the Mont Saint-Michel bay, France.
- Authors
Lefeuvre, Jean-Claude; Bouchard, Virginie; Feunteun, Eric; Grare, Sonia; Laffaille, Pascal; Radureau, Alain
- Abstract
The macrotidal Mont Saint-Michel bay has beenstudied intensively since 1990. The objectives ofthis study, supported by the European Union, wereto understand various processes underlying thefunctioning of this hydrosystem with a special focuson organic matter and nutrient fluxes betweensaltmarshes and marine waters. This paper presents asynopsis of these studies. The tidalflats are unvegetated and primary production isexclusively due to microphytobenthos communitiesdominated by diatoms. Halophile plant communitiescolonize the top parts of the tidal flats. Theircomposition and production vary according to amaturity gradient and sheep grazing. In ungrazedsaltmashes, production ranged from 1080 gDW m-2·yr-1in the lower marsh to 1990 gDW m-2·yr-1in the upper marsh whereas it was only 200 to500 gDW m-2·yr-1in Salicorniaspp.dominated pioneer zones and sheep grazed areas. Mostof this organic matter (OM) was trapped in situ,processed by fungi and bacteria, and then releasedseaward via tidal fluxes, groundwater and runoff as particulate OMand nutrients: –497 kg N, –1200/–1000 kg P-PO4and –9900/–4200 kg inorganic carbon). A small amount ofOM was exported to the bay as macrodetritus. Fattyacids and stable isotopes, used as markers, showedthat OM produced by the marsh halophytes contributedto the diet of all the tidal flats invertebrates thatwere studied. Transient fish species were shown tocolonize the saltmarshes to forage or graze, exporting about 50 tons POM (DW)·y-1. Therefore,it is assumed that the saltmarsh production enhancesthe production of the whole bay. But the functioningis still poorly known because the nutrient sinks havenot all been identified. Part of the nutrients inputwas provided by precipitation (+327 kg y-1), butthe contribution of the catchments was not quantifieddespite the fact that their influence was shown by thepresence of lindane in all the compartments of thesystem. Dynamics of saltmarshes are mainly influencedby natural sedimentation (1.5 million m3·y-1in the bay), plant community succession, and management (i.e., reclamation and agricultural activities).
- Subjects
FRANCE; SALT marsh ecology; ECOSYSTEM management; FOOD chains; HUMUS; ORGANIC compounds
- Publication
Wetlands Ecology & Management, 2000, Vol 8, Issue 2/3, p147
- ISSN
0923-4861
- Publication type
Article
- DOI
10.1023/A:1008440401950