Effets de l'assec sur la distribution de l'azote dans un bassin ostréicole
Gouleau, D.; Feuillet-Girard, M.; Germaneau, J. (1993). Effets de l'assec sur la distribution de l'azote dans un bassin ostréicole, in: Barnabé, G. et al. (Ed.) Production, environment and quality: Proceedings of the International Conference Bordeaux Aquaculture '92, Bordeaux, France, March 25-27, 1992. EAS Special Publication, 18: pp. 493-501
In: Barnabé, G.; Kestemont, P. (Ed.) (1993). Production, environment and quality: Proceedings of the International Conference Bordeaux Aquaculture '92, Bordeaux, France, March 25-27, 1992. Special Publication European Aquaculture Society, 18. European Aquaculture Society: Gent. 587 pp., meer
In: Special Publication European Aquaculture Society. European Aquaculture Society: Bredene. ISSN 0774-0689, meer
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| Auteurs | | Top |
- Gouleau, D.
- Feuillet-Girard, M.
- Germaneau, J.
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| Abstract |
The oyster ponds are organic matter accumulators at the water sediment interface. An empirical ancestral practice "Assec" (drying) is used to clean the ponds. The sediment is exposed to aerobic conditions during several weeks. Then the refilling takes place for a new growth cycle of oysters. The purpose of this experimental drying/rewetting was to show if the organic matter mineralization was stimulated and the fluxes of nutrients across water/sediment interface into the water column were enhanced. Before the drying sequence, ammonium was the predominant nitrogen form in the water column and in the interstitial waters of the upper 5cm layer of the sediment. Concentration of dissolved ammonium increased in sediment with depth, the concentration of exchangeable ammonium, however, decreased with depth. At the end of the drying-sequence, concentration of dissolved ammonium in interstitial water interface was 45 times more than that at the beginning of the drying-sequence. In contrast with the interface, interstitial water ammonium content remained unchanged along the drying sequence, at the 4-5cm level. After the refilling, dissolved ammonium concentrations decreased in the first levels of the sediment (0-5cm). Yet, these concentrations remained much higher than values observed before drying. Consequently, the ammonium fluxes across sediment/water interface became more intense. |
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