Abundance of dissolved polysaccharides in the oxygen minimum layer of the northern Indian Ocean

Abstract

Water samples collected from the upper 1500 m at seven stations in the Bay of Bengal and at five stations in the Arabian Sea, were analysed for dissolved carbohydrate by the MBTH (3-methyl-2-benzothiazolenone hydrazone hydrochloride) method without hydrolysis and after hydrolysis with dilute HCl (0.09 N) and concentrated H sub(2)SO sub(4) (1.2 M). Monosaccharide (MCHO) concentrations averaged 1.88 plus or minus 1.01 mu andM and showed small variations with depth at all stations. Polysaccharides (PCHO) were the most abundant form of total dissolved carbohydrates (TCHO) throughout the water column sampled and accounted for 75 plus or minus and 11% of the TCHO. Hydrolysis-resistant PCHO (HR-PCHO) contributed 48 plus or minusand 16% to the PCHO. Concentrations of PCHO in the lower boundary of the oxygen minimum layer (500 to 1000 m) were generally higher than those observed in the surface waters. Carbohydrate concentrations showed significant negative correlation with dissolved oxygen concentrations. The pattern of carbohydrate distribution reported in this study add to the global picture of carbohydrate distribution