290
D. H. CUSHINQ
the presence of phosphatic deposits offshore (Tooms, 1967); see Fig.
19a, p. 321. It is clear that upwelling extends from Trivandrum near the
southernmost point of India as far north as Panjim, about 300 miles
south of Bombay, but because of its nature and shallow origin the areas
of upwelling cannot be estimated with quite the reliability used in the
other areas. It is possible that the extent of phosphatic deposits
indicates the region of upwelling as well as any other method at the
moment. Carruthers et al. (1959) studied the upwelling off Bombay
during the north-east monsoon and showed that the minimum oxygen
layer is entrained inshore t o rather shallow water ; some evidence was
produced that animals avoid the poor-oxygen water. Banse (1968)
has examined theupwelling system along the whole coast andshows that
an oxygen deficiency can indeed occur below the thermocline during the
upwelling period and catches of demersal fish are reduced in zones of
low oxygen tension (<2 ml/l). It will be shown below that production
is high off the Malabar coast during the north-east monsoon, but it is
likely that it starts towards the end of the south-west monsoon.
In the Bay of Bengal, upwelling has been detected off Walthair in
February and March (Lafond, 1954) ; it probably extends up the coast
to Sangor Island off Calcutta in June. Ganaparti and Murthy (1954)
have described the circulation during this period in the Bay of Bengal.
Under the south-west monsoon, upwelling probably occurs all along the
coast of Orissa, which lies parallel to the direction of the south-west
monsoon. Yet, as will be shown below, high production also occurs on
the Orissa coast during the north-east monsoon. Between December
and January, upwelling is found in the Andaman Sea (Lafond, 1957 ;
Wyrtki, 1961) between the coast of Burma and the Andaman Islands
and off the west coast of Thailand. There is upwelling off the coasts of
Ceylon which appears in Fig. 14, p. 297 from Kabanova (1968). It also
occurs in the shallow Gulf of Thailand, on the west coast in August and
on the north-east coast in October and January ; slight upwelling occurs
all the year round at 12"N and 101"W. Off South Vietnam, upwelling
takes place during the summer monsoon between the central South
Vietnamese coast at Nhatrang and a point some hundreds of miles up
the coast (Wyrtki, 1961).
Wyrtki (1961, 1964) and Rochford (1962) have described upwelling
areas off Java and north-west Australia, and in the Flores, Banda and
Arafura Seas ; those off north-west Australia and in the East Arafura
Sea occur in July and August but are little understood in the distributions of properties. The evidence for the Indonesian areas is based on
certain sections in the absence of charts of surface temperature at the
right season.
D. H. CUSHINQ
the presence of phosphatic deposits offshore (Tooms, 1967); see Fig.
19a, p. 321. It is clear that upwelling extends from Trivandrum near the
southernmost point of India as far north as Panjim, about 300 miles
south of Bombay, but because of its nature and shallow origin the areas
of upwelling cannot be estimated with quite the reliability used in the
other areas. It is possible that the extent of phosphatic deposits
indicates the region of upwelling as well as any other method at the
moment. Carruthers et al. (1959) studied the upwelling off Bombay
during the north-east monsoon and showed that the minimum oxygen
layer is entrained inshore t o rather shallow water ; some evidence was
produced that animals avoid the poor-oxygen water. Banse (1968)
has examined theupwelling system along the whole coast andshows that
an oxygen deficiency can indeed occur below the thermocline during the
upwelling period and catches of demersal fish are reduced in zones of
low oxygen tension (<2 ml/l). It will be shown below that production
is high off the Malabar coast during the north-east monsoon, but it is
likely that it starts towards the end of the south-west monsoon.
In the Bay of Bengal, upwelling has been detected off Walthair in
February and March (Lafond, 1954) ; it probably extends up the coast
to Sangor Island off Calcutta in June. Ganaparti and Murthy (1954)
have described the circulation during this period in the Bay of Bengal.
Under the south-west monsoon, upwelling probably occurs all along the
coast of Orissa, which lies parallel to the direction of the south-west
monsoon. Yet, as will be shown below, high production also occurs on
the Orissa coast during the north-east monsoon. Between December
and January, upwelling is found in the Andaman Sea (Lafond, 1957 ;
Wyrtki, 1961) between the coast of Burma and the Andaman Islands
and off the west coast of Thailand. There is upwelling off the coasts of
Ceylon which appears in Fig. 14, p. 297 from Kabanova (1968). It also
occurs in the shallow Gulf of Thailand, on the west coast in August and
on the north-east coast in October and January ; slight upwelling occurs
all the year round at 12"N and 101"W. Off South Vietnam, upwelling
takes place during the summer monsoon between the central South
Vietnamese coast at Nhatrang and a point some hundreds of miles up
the coast (Wyrtki, 1961).
Wyrtki (1961, 1964) and Rochford (1962) have described upwelling
areas off Java and north-west Australia, and in the Flores, Banda and
Arafura Seas ; those off north-west Australia and in the East Arafura
Sea occur in July and August but are little understood in the distributions of properties. The evidence for the Indonesian areas is based on
certain sections in the absence of charts of surface temperature at the
right season.