. marked migration of'zooplankton from: surface in daylight "*** % SPECIALIZED SURFACE FAUNA PHOSPHATE RETURNED TO WATER ON DECAY OF ZOOPLANKTON nutritive chains of animal organisms, carried in the ocean currents, conveying these substances from the temperate regions of phytoplankton production to the tropical zones of low nutritive content. Fig. 193 shows diagrammatically the two series of events, phenomena which appear to be the same, the one in a time and the other in a space dimension. Each with a reduc- tion of "free" phytoplankton shows a change to a condition when animal
. marked migration of'zooplankton from: surface in daylight "*** % SPECIALIZED SURFACE FAUNA PHOSPHATE RETURNED TO WATER ON DECAY OF ZOOPLANKTON nutritive chains of animal organisms, carried in the ocean currents, conveying these substances from the temperate regions of phytoplankton production to the tropical zones of low nutritive content. Fig. 193 shows diagrammatically the two series of events, phenomena which appear to be the same, the one in a time and the other in a space dimension. Each with a reduc- tion of "free" phytoplankton shows a change to a condition when animal plank- ton may be found in abundance at the surface in bright sunlight. In each we must suppose that the nutritive substances taken from the water by phytoplankton are handed on in a chain of animal or- ganisms shown in the diagram as ABC and D, B feeding on A, C on B, D on C. It is well known that when planktonic animals die and sink the nutritive salts are returned to the water of the lower layers by the action of bacteria, to be brought to the surface in temperate regions by the water disturbances of autumn and winter, or by upwelling, and in our other wider example to be carried back towards the Pole by the warm intermediate current. If this comparison between the events in space across the world from the polar regions to the tropics and the events in time between spring and late summer in the temperate regions is a correct one, then the chain of animal organisms in the former case must be an exceedingly long one. The expression "free phytoplankton" was used above because we must not overlook the role played by the symbiotic algae of the Foraminifera (Globigerina) and the Radiolaria. It seems possible that these organisms may play a much more important part in the economy of tropical seas than is usually attributed to them, in that they may assist in prolonging the transference of nutritive substances in the animal organisms over vast stretches of the ocea
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Keywords: ., bookcentury1900, booksubjectocean, booksubjectscientificexpediti
