A Possible Relation between the Production of Animal Plankton and the Current-System of the Sea

Abstract

The author studied the problem of why spp. of plankton animals are limited in their distribution to distinct areas of the sea despite the fact that they are subject to current action which would tend to distribute them evenly from pole to pole. The spp. studied were Calanus finmarchicus and C. hyperboreus. The studies were made in the Lofoten area of the Norwegian Sea. The distribution and frequency of these 2 spp. in the different areas of the Norwegian coastal waters during spring were found to depend upon the size of the winter stock in the deep waters of the fjords. This winter stock is stationary, not subject to surface currents, and there-fore restricted in distribution. After the spring migration toward the surface, the currents carry the individuals away from the winter areas. In the open oceans the more still-standing water masses, as first advanced by Helland-Hansen and Nansen (1909), appear to contain the stationary stock of plankton animals. From these waters the greater masses in the surrounding areas are renewed every spring. The water masses of the convection currents have been found to be characterized by an increasing deficiency of the spp. along their course, due to changes in ecological factors.