Les appendiculaires du Golfe du Bengale

Appendicularians from 76 hauls made from June to August 1964 in the Bay of Bengal, aboard the R. V. “Kistna”, have been examined. Of the 26 species determined, 10 are new for the Bay of Bengal and, amongst these, 2 were unknown in the Indian Ocean. The composition of the group formed by the most abundant and most frequent species is characteristic of the fauna of the Indian Ocean. Oikopleura longicauda represents 50% of the total number of individuals collected, followed by O. rujescens 14%, Megalocerus huxleyi 8%, O. fusiformis and Fritillaria borealis f. sargassi 6%, O. cophocerca and Stegosoma magnum 2%. No other species reached 1%. The density of the species in the occidental zone deereased fairly regularly with latitude: 21 species in the south, then going on towards the north, 14, 11 and 2. In the area south of the strait of Malacca only 5 species were found, in its opening into the Bay of Bengal, 18. The Oikopleuridae were present in all the hauls, but the Fritillaridae were absent from 25. The geographical distribution of each species has been studied. Oikopleura longicauda is the only one which is clearly more abundant in the north; most of the other species show a decreasing gradient from south to north. The characteristic difference between the different zones cannot be established from the hydrological data (temperature and salinity). It seems, therefore, that the indigenous species are not very common, and that others originate from the Indian Ocean, transported by the south-north currents present at that time of year.