Stream Drift as a Chronobiological Phenomenon in Running Water Ecosystems

Abstract

Waters (141) made a thorough review of stream drift, particularly with regard to insects, in the Annual Review of Entomology (141), providing an excellent survey of the historical development within this special field of running water ecology. This review gives an interpretation of the phenomenon of drift and its function in running water, as well as a presentation of the relevant literature up to 1972. The context in which I take up these problems is one concerning stream drift as a chronobiologic phenomenon. The starting point for this presentation consists of a number of independent studies, performed in various parts of the world, which have shown that stream drift occurs with a diel rhythmic pattern. This finding is based on the extensive investigation of Tanaka (125) in a Japanese stream, Waters (134) in Minnesota, Muller (75) in central Europe, Elliott (23, 25-27, 29, 31, 33) in the British Isles, and Levanidova & Levandov (63, 64) in eastern Siberia. The 24 hr cycle with its continuously changing light-dark periods (depending on the time of year and latitude) causes, directly or indirectly, variations in the physical and chemical factors in running water. It also governs the development and locomotory processes of unicellular algae and the development and behavior of various aquatic invertebrates (including insects) and fish. Stream drift and those activities that underlie it have been found to possess a time-regulated component in running water ecosystems. The above investigations, which have appeared in the last ten years, show that the invertebrates in running water are able to perceive the differentiated day and night length. The duration of activity is positively correlated to the length of the periods of light or darkness.