|Nouvelles observations sur le système production-régénération de l'étang de Berre (littoral méditerranéen)|
Minas, M. (1989). Nouvelles observations sur le système production-régénération de l'étang de Berre (littoral méditerranéen). Mar. Nat. 2(1): 7-17
In: Marine Nature. Marine Science Institute, Yeungnam University: Kyongsan. ISSN 1225-990X
General hydrochemical characteristics of the pelagic ecosystem in the Etang de Berre, brackish lake near Marseilles, are reviewed. Hydrological features and circulation patterns of the lake are those of a dilution basin. A permanent halocline creates. mainly during summer, anoxic conditions in the water near the bottom. Observations made on an overall station grid covering the lake, allow to describe the distribution of main chemical parameters such as oxygen and nutrient salts, and to show that regenerative mineral phosphorus (5 to 6 µatg 1- 1 ) and ammonia (up to 30 µatg 1- 1 ) are associated with oxygen consumption. The anoxic conditions vanish when the water column is thoroughly mixed and ventilated by strong north west winds (Mistral). Nutrients are then liberated from the bottom layer and entertain strong phytoplanktonic blooms. with chlorophyll concentrations reaching more than 50 µg 1- 1 . In winter, the general biological activity of production and nutrient regeneration in the deep layer is reduced, and vertical mixing maintains an aeration of the water bodies. Some comparisons between hydrological and biological features of the Etang de Berre and those of the Baltic Sea are undertaken.