Some Experiments on the Vertical Migration of Zooplankton

Abstract

Hardy & Paton (1947) have described two forms of apparatus with which to study the vertical migration of plankton animals; their intention was to carry out experiments under conditions as natural as possible. In their paper were published results for marine copepods; Paton had also used the instruments on freshwater plankton animals in Windermere, but before he was able to analyse the results, he was killed in action over Malta. After the war, Professor Hardy kindly allowed me to work up the results of Paton's freshwater experiments. One point that emerged from the analysis was that there was a difference in behaviour between animals caught from 15 m to the surface and those caught from 30 m to the surface. Experiments carried out by me in Windermere in 1947 were intended to investigate this diference. A night series was also completed, comparable to one that Paton carried out in 1939. Experiments were also carried out in the North Sea from the Fisheries Research Vessel Sir Lancelot; these consisted of two night series, one at 10 m and the other at 70 m.