Figure 1

(a)Latitudinal variability of δ¹³C values of Globigerina bulloides filled square represents present study, hollow triangle represents data obtained by Khare and Chaturvedi, (2012) (b) δ¹⁸O values of Globigerina bulloides;filled circles represent values of tow samples (present study), hollow diamonds represent values of sediment top samples (from Khare and Chaturvedi, 2012) (c) δ¹⁸O values of surface water samples represented by filled diamonds, square and triangle for 2011, 2012 and 2013 respectively (d) δ¹³C(DIC) values represented by hollow diamonds and square for 2012 and 2013 respectively. The thick grey line represents the chlorophyll-a concentration in mg/m³(zonal mean using data from-MODIS Aqua). Note the similarity of the profiles of changes of δ¹³C(DIC) (from 30 ^oS to 60 ^oS) and that of the chlorophyll-a concentration suggesting connection of isotopic enrichment with organic matter production.