Nutrients and dissolved oxygen in the upper 1000 m in equatorial western Indian Ocean

Abstract

Data collected on board <i>ORV Sager</i> <i>Kanya</i> during August 1985 along the west of 60ᵒE meridian between 4ᵒ N and 6ᵒS latitude indicate considerable difference in nutrient and dissolved oxygen (DO) content in the upper 200 m layer. Warm and nutrient rich water with low oxyty has been observed along 60ᵒE meridian in contrast to the cold and relatively nutrient deficient water with high oxygen to the west of it. In addition, the existence of warm waters with high nutrients and low DO in the north and relatively cold water with low nutrients and high DO in the south is observed. The relationship of DO with nutrients shows a significant negative correlation. The inter-relationship of nutrients, PO₄-P and NO₃-N gives atomic ratios of 12.3:1 and 9.7:1 along section I and II respectively, while SiO₄-Si-ot relationship used for characterizing the watermasses indicates the presence of Arabian Sea surface water, and the Pacific water and the Red Sea water along these 2 sections.