5.5
Some Patterns of the Distribution of Bottom
Fauna in the Indian Ocean
A. A. NEYMAN, M. N. SOKOLOVA, N. G. VINOGRADOVA, and F. A. PASTERNAK
The information available on the composition and distribution of bottom fauna
prior to the organization of the HOE was very inadequate, especially with regard to the
deep-water regions of the open ocean. Therefore, investigations of the patterns of
qualitative and quantitative distribution of bottom fauna were included in the plan of
Soviet oceanological research in the Indian Ocean and carried out using the standard
methods adopted on the research ships of the Soviet Union.
I. The Quantitative Distribution of Bottom Fauna
Systematic studies of the patterns of quantitative benthos distribution were started on
board the "Vityaz" 1959 to 1960 and as a result of 4 cruises much material has
accumulated, collected at stations fairly evenly covering the northern part of the ocean.
The stations occupied in its southern part are not so numerous but here a very complicated
picture of distribution can hardly be expected. Finally, the ships of the Institute of
Marine Fisheries and Oceanography, working mainly in the regions of the continental
shelf, have also begun investigations on the patterns of benthos distribution. Practically
no investigations in this field have been conducted by other expeditions.
Although our knowledge of the quantitative distribution of bottom invertebrates in
the ocean is far from adequate, we may safely assert that it is most closely related to food
supply. The basic food producer in the ocean is phytoplankton and to a far lesser extent,
coastal macrophytes. A distinct zonality is observed in the quantitative distribution of
phytoplankton: generally its abundance increases sharply in a meridional direction from
the near-polar to the boreal regions. Further on, in the tropical zone, the amount decreases
again, reaching here its minimum value. An increase in the abundance of plankton algae,
sometimes quite a significant one, is observed in the equatorial zone. This picture has its
mirror image in the Southern Hemisphere. Near shore this scheme is somewhat obscured
by the fact that here the ascent·of subsurface water rich in nutrients prevails over sinking.
The vertical food chains are those through which the food produced on the surface is
conveyed to the bottom-dwelling consumers. On the floor of the ocean the general
patterns of quantitative life distribution are the same as in the upper layers.
In temperate zones, and especially near the coasts, benthos is far richer than in the
tropics and the open parts of the ocean. Geographical zonality is also related to the
intensity of coastal run-off. But irrespective of its intensity, the amount of organic matter
brought into the ocean from land is not comparable with the quantities produced by
phytoplankton activity. The effect of river discharge on the abundance of benthos is felt
only in the immediate proximity of the mouths of great rivers.
Some Patterns of the Distribution of Bottom
Fauna in the Indian Ocean
A. A. NEYMAN, M. N. SOKOLOVA, N. G. VINOGRADOVA, and F. A. PASTERNAK
The information available on the composition and distribution of bottom fauna
prior to the organization of the HOE was very inadequate, especially with regard to the
deep-water regions of the open ocean. Therefore, investigations of the patterns of
qualitative and quantitative distribution of bottom fauna were included in the plan of
Soviet oceanological research in the Indian Ocean and carried out using the standard
methods adopted on the research ships of the Soviet Union.
I. The Quantitative Distribution of Bottom Fauna
Systematic studies of the patterns of quantitative benthos distribution were started on
board the "Vityaz" 1959 to 1960 and as a result of 4 cruises much material has
accumulated, collected at stations fairly evenly covering the northern part of the ocean.
The stations occupied in its southern part are not so numerous but here a very complicated
picture of distribution can hardly be expected. Finally, the ships of the Institute of
Marine Fisheries and Oceanography, working mainly in the regions of the continental
shelf, have also begun investigations on the patterns of benthos distribution. Practically
no investigations in this field have been conducted by other expeditions.
Although our knowledge of the quantitative distribution of bottom invertebrates in
the ocean is far from adequate, we may safely assert that it is most closely related to food
supply. The basic food producer in the ocean is phytoplankton and to a far lesser extent,
coastal macrophytes. A distinct zonality is observed in the quantitative distribution of
phytoplankton: generally its abundance increases sharply in a meridional direction from
the near-polar to the boreal regions. Further on, in the tropical zone, the amount decreases
again, reaching here its minimum value. An increase in the abundance of plankton algae,
sometimes quite a significant one, is observed in the equatorial zone. This picture has its
mirror image in the Southern Hemisphere. Near shore this scheme is somewhat obscured
by the fact that here the ascent·of subsurface water rich in nutrients prevails over sinking.
The vertical food chains are those through which the food produced on the surface is
conveyed to the bottom-dwelling consumers. On the floor of the ocean the general
patterns of quantitative life distribution are the same as in the upper layers.
In temperate zones, and especially near the coasts, benthos is far richer than in the
tropics and the open parts of the ocean. Geographical zonality is also related to the
intensity of coastal run-off. But irrespective of its intensity, the amount of organic matter
brought into the ocean from land is not comparable with the quantities produced by
phytoplankton activity. The effect of river discharge on the abundance of benthos is felt
only in the immediate proximity of the mouths of great rivers.