Dependence of the Stable Carbon Isotope of Planktic Foraminiferal Species <i>Globigerina Bulloides</i> on Food Supply in the Indian Ocean Sector of Southern Ocean

Abstract

Abstract. Twenty one surface sediment samples (comprising Peterson Grab, Piston, Gravity and Spade core top samples) were collected along a north-south transect (between 9.69°N and 55.01°S latitude and 80°E and 40°E longitude). These samples were used to study δ 13 C values in the calcareous shells of planktic foraminiferal species Globigerina bulloides and the variations were compared with the latitudinal changes in the overall size of the planktic foraminiferal population obtained from earlier published data along similar transect. The results establish an interdependence of δ 13 C values of planktic species Globigerina bulloides and the overall size of planktic foraminiferal population. The region where the δ 13 C values of planktic species Globigerina bulloides decrease the overall size of planktic foraminiferal population increases. Such a distinct pattern may be ascribed to the generation of food/nutritive material. It is suggested that similar studies to understand variations in δ 13 C values in foraminiferal shells and its population size in geographically distinct latitudinal corridors covering distinct marine regime of physico-chemical conditions be undertaken to further strengthen the argument proposed in the present study.