Dynamics of nutrients and faecal bacteria in a macrotidal estuary: the Bay of Somme (France)
Rybarczyk, H.; Desprez, M.; Ducrotoy, J.-P.; Olivesi, R.; Delesmont, R.; Jamet, F.; Elkaim, B. (1993). Dynamics of nutrients and faecal bacteria in a macrotidal estuary: the Bay of Somme (France). Neth. J. Aquat. Ecol. 27(2-4): 395-404. https://dx.doi.org/10.1007/BF02334801 In: Netherlands Journal of Aquatic Ecology. Kluwer Academic Publishers/Netherlands Society of Aquatic Ecology: Bilthoven. ISSN 1380-8427; e-ISSN 2214-7098, more Also appears in:Meire, P.; Vincx, M. (Ed.) (1993). Marine and estuarine gradients: ECSA 21: Proceedings of the 21st symposium of the Estuarine and Coastal Sciences Association held in Gent, 9-14 september 1991. Netherlands Journal of Aquatic Ecology, 27(2-4). Netherlands Society of Aquatic Ecology: Bilthoven. 496 pp., more |  |
| Keywords | Marine/Coastal; Brackish water |
| Authors | | Top | - Rybarczyk, H., more
- Desprez, M.
- Ducrotoy, J.-P., more
- Olivesi, R.
| - Delesmont, R.
- Jamet, F.
- Elkaim, B.
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| Abstract | A stratified methodology for water sampling on tidal flats was adopted in 1988 and 1989 in the Bay of Somme. Analyses of nutrients, particulate matter and faecal germs showed the poor mixing of fresh and marine water and the weakness of stratification of the water column. Freshwater is pushed by marine water to the inner reaches of the bay and there are only a few lenses with true estuarine characteristics. In 1990, water was sampled simultaneously on the Somme river, the tidal flats and in the open sea, in order to point out estuarine gradients of several physical and chemical parameters and their evolution during a tidal cycle. The role of continental inputs was confirmed for faecal pollution, nitrate (20-25 mg 1-1), nitrite and silicate. The importance of ammonium excreted by the estuarine benthic populations was highlighted. High concentrations of continental chlorophyll (450 mg m-3) were also measured and contribute, with nitrates and ammonium, to eutrophication in the Bay of Somme. Pollution of the southern part of the bay by marine waters was regularly observed during the flow, raising doubts about the purifying capacity of sea-water and the conservation of faecal bacteria. A regular survey of fresh-water inputs and sea-water quality, offshore and within the bay, is considered to enable estimation of their respective influences in eutrophication processes in the Bay of Somme. |
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