Green Global
Foundation   Journal
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STUDY ON MONTHLY VARIATIONS OF PLANKTON IN RELATION TO THE PHYSICO- CHEMICAL CONDITION OF RICE-FISH FIELDS IN BORO SEASON (Pages : 43 - 49)

A study was conducted at the rice-fish plots of Rajbari and Faridpur district to observe the monthly variations of plankton (qualitatively and quantitatively) in relation to the physico-chemical conditions in boro season. Water quality parameters and different genera of plankton belonging to different groups were recorded and identified during the study. A total of 23 genera of phytoplankton belonging to 4 major group viz., Chlorophyceae (11), Euglenophyceae (2), Cyanophyceae (4) and Bacillariophyceae (6) and 7 genera of zooplankton belonging to 2 major groups viz., Crustacea (3) and Rotifera (4) were identified. Some nauplius were found along with zooplankton. The recorded water quality parameters such as temperature, transparency, dissolved oxygen, pH, CO2, bicarbonate and chlorophyll-a in the rice-fish plots were found to be in the suitable range for fish culture. A correlation coefficient was made between the different major groups of plankton and physico-chemical parameters of water to find out the roles of them. Both physico-chemical and biological conditions varied monthly and showed an inverse relationship between them. Cyanophyceae and Chlorophyceae were the most dominant food group for fish among phytoplankton population. Phytoplankton population was also found to be highly dominant over zooplankton population. Water temperature vs Cyanophyceae and Clorophyceae showed strong positive (r=0.75 and 0.73) correlations. Cyanophyceae, Chlorophyceae, Euglenophyceae, Bacillariophyceae, Crustacea and Rotifera showed negative and weak relationship with water transparency, CO2 and bicarbonate while, Cyanophyceae, Chlorophyceae, Euglenophyceae, Bacillariophyceae, Crustacea and Rotifera showed positive correlations with water temperature, pH, dissolve oxygen and Chlorophyll-a. Download