Monthly variations of benthic community in relation to hydrological parameters in the ponds of Bangladesh agricultural university, Bangladesh

Abstract

A study on the monthly abundance of benthic fauna in accordance with different depths related to physico-chemical characteristics of water was conducted in the Bangladesh Agricultural University Fish Farm Pond, Mymensingh, during the period from July to December, 2007. During the study period monthly sampling of benthic fauna were collected from three depth ranges 100-170 cm, 170-230 cm and 230-290 cm from three stations (east, middle and west) in the pond and the samples were analyzed. Monthly changes in physico-chemical characteristics were observed in the ponds which were divided into three treatments (1 meter, 2 meters and maximum depth) from three stations. Twelve genera such as Branchiura, Ophidonais, Dero, Choaborus, Aelosoma, Peloscolex, Chironomus, Pelopia, Vviparous, Pila, Planorbis and Lymnaea under three groups such as Oligochaeta, Chironomidae and Mollusca were encountered during the study period. The successive position of five genera such as Branchiura, Ophidonais, Chironomus, pelopia and Dero were found the most dominant genera. Benthos was most dominant in treatment II followed treatment I and III. The benthic fauna was mostly made up of Oligochaetes, Chironimids and Mollusks constituting the most dominant groups. The maximum number of organisms (Number/m2) was collected in July followed by October, November, August, September and December in the pond. The fluctuations of benthic fauna were found to be more or less related to pH, temperature, dissolved oxygen and as well as depth of the water body. Stations, where raw cow-dung was used as fertilizer, resulted in dead gastropods.