Diel dynamics of heleoplankton in relation to some physico-chemical attributes of water in an aquaculture tank in Guwahati, Assam

Diurnal fluctuation of the phytoplankton and zooplankton population (numerical densities) and the physicochemical attributes of water are studied in an aquaculture pond at Guwahati, Assam. In the 24 hour diel cycle, the phytoplankton and zooplankton show significant (t-test, p < 0.01) variation in their numerical density at an interval of 4 hours. The studied physico-chemical parameters of water included Temperature, Total Alkalinity (TA), Total hardness (TH), Dissolved Oxygen (DO), Free Carbon dioxide (FCO2) and pH are analyzed concurrently, which reveals a significant fluctuation (t-test, p< .01) in the day and night hours. Multivariate correlation analysis portrays significant and positive correlations among the total population density of phytoplankton with respect to water temperature (r = 0.845, p<0.05) and pH (r = 0.881, p< 0.01) while it maintains significant negative correlations with TA (r = -0.837, p<0.05), TH (r = -0.768, p< 0.05) and FCO2 (r = -0.830, p<0.05). However, total numerical density of zooplankton reveals positive and significant correlations with TA (r = 0.842, p< 0.05) and FCO2 (r= 0.758, p< 0.05) while it shows significant negative correlations with water temperature (r = -0.906, p< 0.01) and pH (r =- 0.912, p< 0.01)