The Vertical Distribution of Marine Macroplankton. VI. Further Observations on Diurnal Changes

Abstract

In 1925 observations were carried out on two consecutive nights, June 17–18th and 18–19th, to study the diurnal changes occurring in the vertical distribution of certain marine plankton animals. Serial hauls were made with the stramin ring-trawl in the manner described in a previous publication (1). The series were so timed that they were made approximately in daylight, dusk, darkness, dawn and daylight on the two days in question. The actual details of the collecting, together with the fishing depths shown by the Admiralty depth recorder, are to be found in a previous paper on the behaviour of young fishes on the same occasion (2).