120
]. KREY:
3 oceans is rather constant. Concentrations of over 100000 cells 1-1 would also be
expected in the upwelling regions along the Arabian coast and the SW coast of India. The
Equatorial Current region and the Arabian Sea would have an abundance of some 10 000
cells 1-\ and the southern subtropical gyre and central Bay of Bengal region low to very
low plankton concentrations, usually less than 5000 cells 1-1.
Table 2. List of mass forms of the phytoplankton in the Indian Ocean
Bacillariophyceae:
Asterionella japonica
Bacteriastrum hyalinum var. princeps
Biddulphia heteroceros
B. mobiliensis
Chaetoceros affinis
C. brevis
C. compressus
C. contortum
C. curvisetus
C. lasciniosus
C. lauderii
C. lorenzianus
C. pelagicus
C. socialis
Coscinodiscus asteromphalus
C. oculus-iridis
Fragilaria oceanica
Guinardia flaccida
Lauderia annulata
Leptocylindrus danicus
Nitzschia seriata
N. sigma var. indica
Rhizosolenia alata
R. robusta
R. stolterfothii
Sceletonema costa tum
Schriiderella delicatula
Thalassiothrix frauenfeldii
T. longissima
Dinophyceae:
Ceratium fusus
C. macroceros
C. tripos
Dinophysis caudata
Glenodinium lenticula f. asymmetrica
Noctiluca miliaris
Peridinium depressum
Myxophyceae:
Trichodesmium erythraeum
II. Distribution of Chlorophyll
Fig. 4 shows the annual average distribution and the variations in concentration of
chlorophyll in the upper 50 m layer of the Indian Ocean; the range in variation is of the
order of 1 : 100. This would give only a rough estimate of the total photosynthetic capacity
of the water mass since we cannot differentiate between living and dead chlorophyll.
HENTSCHEL calculated on the basis of his observations that no living chlorophyll is
present below a depth of 200 m. The chlorophyll distribution charts are of limited use
in estimating standing stock accumulations or primary production rates; for a better
correlation, we have to allow for the fluctuations in per-cell chlorophyll concentration
from species to species, the physiological state of the population, particularly the light
adaptation level, vertical transportation and grazing rates, and the amount of detritus in
the standing stock, etc. Figs. 4 and 5 show the horizontal distribution of chlorophyll
concentration during the periods June-September and December-March, which gives
us some idea of the extent and locations of the fertile areas during the various biological
seasons. If, for the June - September period, we define areas with a chlorophyll concentration above 0.5 mg m -3 as fertile and those below it as infertile from the point of view
of primary productivity, there are clearly two areas of high fertility, one on the east coast
]. KREY:
3 oceans is rather constant. Concentrations of over 100000 cells 1-1 would also be
expected in the upwelling regions along the Arabian coast and the SW coast of India. The
Equatorial Current region and the Arabian Sea would have an abundance of some 10 000
cells 1-\ and the southern subtropical gyre and central Bay of Bengal region low to very
low plankton concentrations, usually less than 5000 cells 1-1.
Table 2. List of mass forms of the phytoplankton in the Indian Ocean
Bacillariophyceae:
Asterionella japonica
Bacteriastrum hyalinum var. princeps
Biddulphia heteroceros
B. mobiliensis
Chaetoceros affinis
C. brevis
C. compressus
C. contortum
C. curvisetus
C. lasciniosus
C. lauderii
C. lorenzianus
C. pelagicus
C. socialis
Coscinodiscus asteromphalus
C. oculus-iridis
Fragilaria oceanica
Guinardia flaccida
Lauderia annulata
Leptocylindrus danicus
Nitzschia seriata
N. sigma var. indica
Rhizosolenia alata
R. robusta
R. stolterfothii
Sceletonema costa tum
Schriiderella delicatula
Thalassiothrix frauenfeldii
T. longissima
Dinophyceae:
Ceratium fusus
C. macroceros
C. tripos
Dinophysis caudata
Glenodinium lenticula f. asymmetrica
Noctiluca miliaris
Peridinium depressum
Myxophyceae:
Trichodesmium erythraeum
II. Distribution of Chlorophyll
Fig. 4 shows the annual average distribution and the variations in concentration of
chlorophyll in the upper 50 m layer of the Indian Ocean; the range in variation is of the
order of 1 : 100. This would give only a rough estimate of the total photosynthetic capacity
of the water mass since we cannot differentiate between living and dead chlorophyll.
HENTSCHEL calculated on the basis of his observations that no living chlorophyll is
present below a depth of 200 m. The chlorophyll distribution charts are of limited use
in estimating standing stock accumulations or primary production rates; for a better
correlation, we have to allow for the fluctuations in per-cell chlorophyll concentration
from species to species, the physiological state of the population, particularly the light
adaptation level, vertical transportation and grazing rates, and the amount of detritus in
the standing stock, etc. Figs. 4 and 5 show the horizontal distribution of chlorophyll
concentration during the periods June-September and December-March, which gives
us some idea of the extent and locations of the fertile areas during the various biological
seasons. If, for the June - September period, we define areas with a chlorophyll concentration above 0.5 mg m -3 as fertile and those below it as infertile from the point of view
of primary productivity, there are clearly two areas of high fertility, one on the east coast