Nutriclines and nutrient stoichiometry in the eastern Arabian Sea: Intra-annual variations and controlling mechanisms

•Depth of 26 °C isotherm can be used as a proxy to determine the depth of nitracline being both strongly correlated.•This correlation is strongest in the stratified south.•Nutrient enrichment periods exhibit high excess phosphate due to surfacing of nitrogen deficit intermediate waters.•Diazotrophy reduces the excess phosphate concentrations during the post nutrient enrichment periods.•Unutilised excess phosphate during oligotrophic spring season indicates possible iron limitation for diazotrophy.