salinity is relatively high in this layer, 35-5 to 3^ per mille, 

 the salinity maximum is found slightly below it. A high nitrite 

 concentration^, probably the highest in the world oceans, is also 

 associated with the "minimum oxygen of the Arabian Sea. The upper 

 boundary of the layer is relatively sharp and coincides with the 

 sharp thermocline which varies with the seasonal upvelling or 

 coastal piling up of surface waters according to the prevailing 

 monsoon. Mass mortality of fish has been reported along the 

 Arabian and Indian coasts in seasons when upwelling of the layer 

 of minimum oxygen is to be expected. Such mass mortality might 

 very well be caused by the lethal effect of the low oxygen content 

 or in conjunction with the accompanying "red tides." 



Some investigations off Bombay sponsored by the United Nations 

 Educational, Scientific and Cultural Organization in October and 

 November of 1958'" found the layer with an average oxygen content of 

 0.7 ml/l. occurring at an average depth of about l8 meters some 18 

 nautical miles out from the coast. During this season the layer 

 of minimum oxygen is expected to approach the surface under the 

 Influence of the upwelling near Bombay which is caused by the 

 direction of the monsoon wind. The slope of the discontinuity 

 layer was upward toward the coast and intersected the bottom at 

 about 7 fathoms. The phosphate content in the layer of minimum 

 oxygen was relatively high (greater than 1 ugm. at. /liter. ), The 

 salinity was about '^6.0 per mille and the temperature around 2U°C. 

 The upper boundary of the layer seems to rise and fall with the 



■■■Dr. J. W. Carruthers, S. S. Gogate, J. R. Kaidu, and T. 

 Laevastu, "Shoreward Upslope of the Layer of Minimum Oxygen off 

 Bombay/' Nature, CXXCIII (it668), 108^1-1087 (Apr. l8, 1959)- 



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