Dinet A., Sornin J. M., Sabliere A., Delmas D., Feuilletgirard M.
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The influence of biodeposition by filter-feeding bivalves (Crassostrea gigas and Mytilus edulis) on the evolution of salt-marsh meiobenthic communities of the French atlantic coast was studied over a 15-months period. Quantitative variations of meiofauna were analyzed monthly and, during some phases of the year cycle, at two or three-days intervals. The reasons for the recorded faunal variations were searched by principal component analysis among the main physico-chemical factors of the environment and more especially those related to the particulate organic matter of sediments. Over the concerned period, it seemed difficult to point out the subtle effects of biodeposition on meiofauna as the seasonal factor, basically thermal, was found responsible for the largest quantitative variations observed in the communities. Nematodes and harpacticoid copepods inversely reacted to the massive input of biodeposits. Finally, the most striking effect of these was a lowering of populations very likely due to the strong reduction of the substrate (negative Eh) and a rather high content of ammonium in interstitial waters.
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