Abstract
(1) Analysis of data of phyto- and zooplankton for about 30 weeks (1961–62) collected from Gandhisagar, Nagpur, to show the relative population at different hours of the day with special reference to behaviour of some specific forms is discussed. (2) The data relating to dissolved oxygen, temperature, total alkalinity, oxygen consumed, biochemical oxygen demand, pH and free carbon-dioxide are available. It is difficult to correlate the diurnal variation to any or all of these factors except the dissolved oxygen. (3) The principle factor involved in the diurnal movement of plankton is light, and other factors mentioned above are likely to cause these movements but it is difficult to point to one or even the totality of all factors as responsible for these movements. (4) Among the zooplanktonic forms those with weak locomotion show very restricted diurnal variation. The zooplankton forms avoid strong light and are generally found to be less in numbers in samples collected during day than in samples collected after sunset. In the case of cladocerans and copepods the diurnal movement is very characteristic.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
