Living Planktonic Foraminifera at the 90°E Meridian from the Equator to the Antarctic

The planktonic foraminiferal fauna was studied in 206 samples gathered by the Royal Research Ship Discovery II at the 90°E meridian of longitude between the equator and the coast of Antarctica. Samples were collected throughout the water column from 1500 to 0 m. Twenty-seven species were recognized, and their horizontal and vertical distributions were established. Five types of surface water masses were distinguished on the basis of differences in foraminiferal fauna, and the geographical positions of these water masses were determined and plotted. It was found that differences exist between the geographic positions of the hydrological fronts established by means of temperature and salinity data, and those determined by means of foraminiferological data. Explanations for these discrepancies are given. The percentage of empty shells with respect to the total number of foraminiferal shells at different depths was calculated.