STUDIES ON THE SEASONAL SUCCESSION OF CLADOCERANS IN A PERENNIAL PONDECOSYSTEM OF TRIPURA

The present study was undertaken on a perennial pond ecosystem of Tripura to study the seasonal density and abundance of cladoceran fauna during a period from March 2012 to February 2013. A total of 10 species of cladoceran fauna viz., Daphnia magna. Daphnia similis, Ceriodaphnia cornuta, Ceriodaphnia reticulata, Moina micrura, Macrothrix goeldi , Macrothrix rosea , Chydorus sphaericus . Leygidia acanthocercoides and Alona sp. were recorded. Amongst cladoceran fauna, Ceriodaphnia reticulata was the most predominant species both quantitatively as well as qualitatively. The percentage composition of each cladoceran species as well as their belonging families were also noted. Cladoceran population followed a definite rhythm of seasonal abundance showing highest density in the Summer (102 No/ mo) and lowest in the monsoon (38 Not m) during the study period. Numerical abundance of cladoceran fauna was observed in the peripheral zone of aquatic macrophytes. Physico-chemical parameters of the studied pond water were also observed during the study period. The density of cladoceran zooplankton showed significant positive correlation with water temperature (r = 0.812, P - 0.05) and pH (r = 0.827, P < 0.01) whilst negative correlation was observed with free carbon dioxide (r = - 0.503, P < 0.01).