Comparative plankton ecology of five fish tanks in Delhi, India

Abstract

A comparative account of the plankton ecology of five fish tanks in Delhi is given. Variations in the physical and chemical characteristics of water such as temperature, turbidity, total residue, pH, free carbon dioxide, carbonate alkalinity, total alkalinity, total hardness, chlorides, dissolved oxygen, oxygen consumed, phosphates, nitrates, silicates and sulphates observed for a period of one year are described. Chemical characteristics of water vary to a great extent in the five tanks. The dry summer and the monsoon rains considerably influence the physical and chemical conditions of water. The quantitative variations in the phytoplankton populations are presented. Compared to temperate waters, the tanks in Delhi show a richer variety of organisms. The largest number of genera is noted among the green algae. Desmids are poorly represented in all the tanks. The phytoplankton populations show a regular winter maximum which is caused by diatoms. Observations on the quantitative variations in the major groups of zooplankton are presented. Zooplankton population is represented by many genera. The dominant group among the zooplankton is the Rotifera which shows a summer maximum. There is no significant correlation between the phytoplankton and the zooplankton.