Light and Nutrients in the Indian Ocean
85
plankton, according to ZERNOVA and IVANOV (1964). GARG, MURTY and JAYARAMAN
(1968) analysed the vertical distribution of O 2 in February- March and found greater
thickness of an Orrich layer in the Bay of Bengal than in the Andaman Sea. Below this,
an 02-poor layer showed greater thickness in the Andaman Sea and decreased toward
the north in the Bay of Bengal, suggesting a northerly flow at these depths. Upwelling
along the Burmese coast during the NE Monsoon is reported by LAFoND and LAFoND
(1968), based on observations during the period of shift from NE to SW monsoon winds
(March). RAO and JAYARAMAN (1968 b) find the spreading of river discharge from the
Irrawaddy in the upper 75 m a major influence in the SE area in the premonsoon months.
fJfJ) Northern Latitudes, Bay of Bengal-Calcutta, Waltair
SANKARANARAYANAN and REDDY (1968) studied the distribution of phosphine,
nitrate and silicate in relation to hydrographical features of the NW region of the Bay
between 16° Nand 19° N latitude during the month of January. Although there was
marked regional variation, the distribution was found to be related to the prevailing
currents. The chief feature observed was the commencement of coastal upwelling along
the east Indian coast which develops as the SW monsoon winds become established
(April) . RAo and RAO (1968) report variation in the surface values for total phosphorus
from a low of 0.99 Jlg-at 1- 1 in April to a high of 3.4 Jlg-at 1- 1 in July.
The high values of total phosphorus in the summer coincide with low values of inorganic phosphate, following the variations in the standing stock. The total phosphorus
is generally low in surface waters and increases with depth up to 500 m, after which
the values decrease. SANKARANARA Y ANAN and REDDY likewise find vertical movement
of the water down to 500 m. The inorganic phosphate maximum occurs between 600
and 800 m, the nitrate maximum at 300 to 800 m. Silicate concentrations, on the other
hand, continue to increase with depth.
No enrichment of the surface waters by inorganic phosphate in the SW monsoon
was found by RAO and RAO (1968) . Rather, they attribute the high total phosphorus
value to the large quantities of dissolved organic phosphorus present, which can contribute 80 to 90% of the total phosphorus.
yy) Coromandel Coast-Madras, Porto Novo, Kalinda
BANSE (1968) finds no marked seasonal upwelling off Madras. He further claims the
river discharge during the SW monsoon does not contribute important amounts of
phosphate-phosphorus to the sea. MURTY and VARADACHARI (1968) review the physical
characteristics of surface waters off Madras and Karaikal and find only weak upwelling
in the premonsoon season. Water from shallow depths reaches the surface nearshore
but there is no marked lowering of the surface temperature. This is in distinct opposition
to the prominent upwelling seen off Waltair during both premonsoon and monsoon as
the water from deeper layers off the shelf appears to reach the surface causing considerable
fall of surface temperatures near the coast. MURTY and REDDY (1968) also find little
evidence for pronounced upwelling near Madras, based on total phosphorus distribution
in the sediments.
(0) Southwest Coast of India-Malabar Coast
PANNlKAR and JAYARAMAN (1966) reviewed the evidence for upwelling conditions
on the SW coast of India and concluded that upwelling was prevalent along the coast
85
plankton, according to ZERNOVA and IVANOV (1964). GARG, MURTY and JAYARAMAN
(1968) analysed the vertical distribution of O 2 in February- March and found greater
thickness of an Orrich layer in the Bay of Bengal than in the Andaman Sea. Below this,
an 02-poor layer showed greater thickness in the Andaman Sea and decreased toward
the north in the Bay of Bengal, suggesting a northerly flow at these depths. Upwelling
along the Burmese coast during the NE Monsoon is reported by LAFoND and LAFoND
(1968), based on observations during the period of shift from NE to SW monsoon winds
(March). RAO and JAYARAMAN (1968 b) find the spreading of river discharge from the
Irrawaddy in the upper 75 m a major influence in the SE area in the premonsoon months.
fJfJ) Northern Latitudes, Bay of Bengal-Calcutta, Waltair
SANKARANARAYANAN and REDDY (1968) studied the distribution of phosphine,
nitrate and silicate in relation to hydrographical features of the NW region of the Bay
between 16° Nand 19° N latitude during the month of January. Although there was
marked regional variation, the distribution was found to be related to the prevailing
currents. The chief feature observed was the commencement of coastal upwelling along
the east Indian coast which develops as the SW monsoon winds become established
(April) . RAo and RAO (1968) report variation in the surface values for total phosphorus
from a low of 0.99 Jlg-at 1- 1 in April to a high of 3.4 Jlg-at 1- 1 in July.
The high values of total phosphorus in the summer coincide with low values of inorganic phosphate, following the variations in the standing stock. The total phosphorus
is generally low in surface waters and increases with depth up to 500 m, after which
the values decrease. SANKARANARA Y ANAN and REDDY likewise find vertical movement
of the water down to 500 m. The inorganic phosphate maximum occurs between 600
and 800 m, the nitrate maximum at 300 to 800 m. Silicate concentrations, on the other
hand, continue to increase with depth.
No enrichment of the surface waters by inorganic phosphate in the SW monsoon
was found by RAO and RAO (1968) . Rather, they attribute the high total phosphorus
value to the large quantities of dissolved organic phosphorus present, which can contribute 80 to 90% of the total phosphorus.
yy) Coromandel Coast-Madras, Porto Novo, Kalinda
BANSE (1968) finds no marked seasonal upwelling off Madras. He further claims the
river discharge during the SW monsoon does not contribute important amounts of
phosphate-phosphorus to the sea. MURTY and VARADACHARI (1968) review the physical
characteristics of surface waters off Madras and Karaikal and find only weak upwelling
in the premonsoon season. Water from shallow depths reaches the surface nearshore
but there is no marked lowering of the surface temperature. This is in distinct opposition
to the prominent upwelling seen off Waltair during both premonsoon and monsoon as
the water from deeper layers off the shelf appears to reach the surface causing considerable
fall of surface temperatures near the coast. MURTY and REDDY (1968) also find little
evidence for pronounced upwelling near Madras, based on total phosphorus distribution
in the sediments.
(0) Southwest Coast of India-Malabar Coast
PANNlKAR and JAYARAMAN (1966) reviewed the evidence for upwelling conditions
on the SW coast of India and concluded that upwelling was prevalent along the coast