The Vertical Distribution of Marine Macroplankton IV. The Apparent Importance of Light Intensity as a Controlling Factor in the Behaviour of Certain Species in the Plymouth Area.

Abstract

Results of collections with the ring-trawl to obtain evidence on the vertical distribution of plankton animals in daylight at different times of the year and at night are given.The vertical distribution of Calanus finmarchicus and Cosmelira pilosella is discussed in relation to the distribution of light intensity in the sea.Results show that light intensity is apparently the external factor of greatest importance in determining the vertical distribution of these plankton animals in this region.Many more observations at sea correlated with simultaneous records of light intensity at different depths are required, together with laboratory experiments on the effects of various factors on the behaviour of plankton animals kept under different conditions of light intensity.