Size variations of planktonic foraminiferal population in the Indian Ocean sector of Southern Ocean

Abstract

Twenty five surface sediment samples (comprising Peterson Grab, Piston, Gravity and Spade core top samples) were collected along a north-south transect (between 9.69º N and 55.01º S latitude and 80º E and 40º E longitude). On the basis of overall size, the total planktonic population has been divided into two groups (> 120 μm sized population and <120 μm sized population). The results show an apparent interrelationship between shell size and variations in hydrographic conditions such as food availability/nutrition (phosphate) of ambient water masses. It is apparent that nutrients play a significant role in determining the size of the foraminiferal population and an increase in the nutrient supply is conducive for the growth of the planktonic population.