2. Primary Production and Standing Stock of Phytoplankton
and Bacteria
2.1
Primary Production in the Indian Ocean I
J. KREY
One of the basic aims of the International Indian Ocean Expedition (IlOE) was to
accumulate data on the rate of primary production in the region and the environmental
phenomena that regulate it. These data could then be used to prepare distribution charts
which would show, among other things, areas of seasonal extremes in high and low
productivity, and their spatial and temporal variations. A good understanding of these
processes in the Indian Ocean is of great importance in the construction of models of
seasonal energy transfer and the food pyramid and for their theoretical interpretation.
Such models must take into consideration the influences of the Indian Ocean monsoons,
intensity of upwelling, circulation pattern, etc., and the effects of these on rate of
sedimentation, secondary production and spatial transfer. From the models, we could
then estimate the level of fish production that each area could theoretically support and
indicate regions of potentially exploitable fisheries.
Under the expedition program, a large number of research ships belonging to several
countries carried out intensive investigations in the region during the period 1959 -1965.
It is extremely unfortunate that, except for restricted areas of individual interest, the
cruise itineraries were not coordinated with regard to times and points of observation and
methods so as to ensure a somewhat more uniform series of investigations over the whole
region. The consequent heterogeneity in distribution, both spatial and temporal, means
that observation points cluster around certain areas while there are large gaps in some
other regions. The 110° E longitudinal section under the Australian program and the
Arabian Sea were well studied, the latter clearly because of the number of unique
oceanographic phenomena observed there; in contrast, the central southern Indian Ocean
region was not adequately covered. To obtain a more complete picture for the whole
Indian Ocean, observations carried out before and after the HOE are also taken into
consideration in the following discussions.
I. Phytoplankton Distribution
During the "Meteor" expedition, HENTSCHEL (1936) made a detailed study of both the
latitudinal and vertical distribution of phytoplankton in the southern Atlantic Ocean on
the basis of a large number of comparable samples concentrated by centrifugation.
One of his most outstanding results was to show the distinct relationship between
regions of high phosphate concentration and areas of large phytoplankton accumulations,
irrespective of the size of the organisms contributing to the maxima; in general, these
were the regions of upwelling and river discharge. HENTSCHEL also found a dose eo[-
and Bacteria
2.1
Primary Production in the Indian Ocean I
J. KREY
One of the basic aims of the International Indian Ocean Expedition (IlOE) was to
accumulate data on the rate of primary production in the region and the environmental
phenomena that regulate it. These data could then be used to prepare distribution charts
which would show, among other things, areas of seasonal extremes in high and low
productivity, and their spatial and temporal variations. A good understanding of these
processes in the Indian Ocean is of great importance in the construction of models of
seasonal energy transfer and the food pyramid and for their theoretical interpretation.
Such models must take into consideration the influences of the Indian Ocean monsoons,
intensity of upwelling, circulation pattern, etc., and the effects of these on rate of
sedimentation, secondary production and spatial transfer. From the models, we could
then estimate the level of fish production that each area could theoretically support and
indicate regions of potentially exploitable fisheries.
Under the expedition program, a large number of research ships belonging to several
countries carried out intensive investigations in the region during the period 1959 -1965.
It is extremely unfortunate that, except for restricted areas of individual interest, the
cruise itineraries were not coordinated with regard to times and points of observation and
methods so as to ensure a somewhat more uniform series of investigations over the whole
region. The consequent heterogeneity in distribution, both spatial and temporal, means
that observation points cluster around certain areas while there are large gaps in some
other regions. The 110° E longitudinal section under the Australian program and the
Arabian Sea were well studied, the latter clearly because of the number of unique
oceanographic phenomena observed there; in contrast, the central southern Indian Ocean
region was not adequately covered. To obtain a more complete picture for the whole
Indian Ocean, observations carried out before and after the HOE are also taken into
consideration in the following discussions.
I. Phytoplankton Distribution
During the "Meteor" expedition, HENTSCHEL (1936) made a detailed study of both the
latitudinal and vertical distribution of phytoplankton in the southern Atlantic Ocean on
the basis of a large number of comparable samples concentrated by centrifugation.
One of his most outstanding results was to show the distinct relationship between
regions of high phosphate concentration and areas of large phytoplankton accumulations,
irrespective of the size of the organisms contributing to the maxima; in general, these
were the regions of upwelling and river discharge. HENTSCHEL also found a dose eo[-