Meridional variations in N* and Si* along 57°30′E and 47°E transects in the indian sector of the Southern Ocean during austral summer 2011

Abstract The variations in nutrient utilization in the euphotic layer was studied using geochemical tracers N* (NO3- −16PO43−) and Si* (Si(OH)4 – NO3-) along two transect 57°30′E (T1) and 47°E (T2) during austral summer 2011 in the Indian Ocean sector of the Southern Ocean. Seawater samples collected from 8 depths within the euphotic zone (upper 200 m) along two meridional transects were analysed for nitrate, nitrite, silicate, phosphate and chlorophyll a (chl a). Clear meridional differences in nutrient limitation were observed along the two transects. Depletion of silicate at Antarctic Zone (AZ) stations was 1.6 times higher in T1 than in T2. Significant inverse correlations were observed for N* (p