Abstract
Diurnal rhythm of Planktonic organisms in relation to various physico-chemical variables was monitored during dry, hot and rainy seasons in Jos Plateau (Nigeria) water reservoir. Diurnal fluctuations in water temperature, dissolved oxygen concentration, free carbon dioxide, total alkalinity and specific conductance were significant. pH was circum-neutral throughout with relatively narrow diel variations. Chloride content seemed conservative, exhibiting little fluctuation. This investigation describes the role of the diurnal cycle of various abiotic environmental factors in regulating the diurnal movement of plankters.
