Campagne ANTIPROD I - Marion Dufresne. 1-28 mars 1977

During the cruise Antiprod I of the supply-ship "Marion- Dufresne" of the TAAF (March lst-March 28, 1977), the characteristics of the planktonic production and of the factors which condition it have been studied in the Indian Ocean in the region of influence of the antarctic divergence at the end of the summer. We are presenting the essential data of the work done in the scope of a descriptive study : 29 stations situated along a N-S line, between 40 and 62°S, West of the Kerguelen islands. The most interesting results concern : - the demonstration of an unusual hydrological structure in the Antarctic, with antarctic and subtropical convergencies joining. - the marked poverty of the phytoplankton : the maximal biomass and the resulting transparency of the waters can be compared to the oligotroph seas, such as the Mediterranean. - the very particular behaviour of the silicates which are used up (or are not renewed) much more quickly than the other nutrients when the waters of the divergency drift northwards