Chlorophyll profile of the euphotic zone in the Lakshadweep Sea during the southwest monsoon season

Abstract

The distribution of chlorophyll a, b and c, the inorganic phosphate and nitrite of the euphotic zone at 56 locations in the Lakshadweep Sea was studied during the southwest monsoon period of 1990. The average chlorophyll a concentration varied from 4.62 mg/m^ at the surface to 2.23 mg/m^at 50 m depth with a column mean of 161 mg/m^ in the euphotic zone. The chlorophyll b averaged to 2.28 mg/m^ at 10 m to 2.79 mg/m^ at 50 m depths and 115 mg/ m^ in the column. The chlorophyll c varied from 4.03 mg/m^ at the surface to 4.97 mg/m^ at the 20 m depth and showed an average value of 202 mg/m^for the column. The chlorophyll c was the dominant pigment in the water column throughout the period of study. The average ratios of chlorophyll c/a and b/ a fell in the range of 1.3 - 2.4 and 0.80 - 1.3 respectively and were positively correlated with depths in the euphotic zone. The inorganic phosphate values fluctuated from 0.65 fig at/1 at surface to 1.36 |ig at/1 at 50 m depth with a mean of 49 mg at/m^ in the water column. The nitrite concentration varied widely, very often below the level of detection.