Fig. 4From: A critical assessment of marine predator isoscapes within the southern Indian Oceana Plasma δ13C (left) and δ15N (right) isoscapes calculated as the mean of 1000 bootstrapped surfaces interpolated using ordinary kriging which randomly sampled twenty-two individuals from all five flying species to account for different numbers of individuals per species. b Isoscapes, using the same bootstrap technique, modelled without the species which did not exhibit a significant latitudinal gradient (i.e. sooty albatrosses were removed from the δ13C isoscape and sooty and grey-headed albatrosses and northern giant petrels were removed from the δ15N isoscape). Position of the sub-tropical (STF), sub-Antarctic (SAF) and Antarctic polar (PF) fronts and Marion Island (black triangle) are indicatedBack to article page