Les facteurs de verdissement de l'huître en claires : le milieu hydrobiologique et benthique et ses variations

In a preliminary work (MOREAU, 1967), the importance of the role of pigments in fattening ponds and the part they played in the process of Navicula ostrearia B.'s pigmentation had been studied in fattening ponds situated at two different points of the Marennes-Oléron basin. The first of these fattening ponds were located in the Seudre Valley, at La Tremblade and at Eguillate, the second ones in the Daire area more widely fed by coastal waters and where the greening conditions of the fattening ponds are different from those observed in Seudre (figure 1 and table 1). 370 Dosing the potency of various chlorophylls had highlighted a noticeable constancy of chlorophyll B and, a variance for those of type A and C (table 2) which had made it possible to conclude that the pigmentation of N. ostrearia was due to a state of chlorosis from the deterioration of the photosynthetic pigments and consequently of the capability of photosynthesis. This research has since been directed towards the study of fattening ponds themselves: environmental conditions, and factors likely to change the characteristics of them and thus influence the phenomenon of greening.