FISH DIVERSITY AND WATER CHARACTERISTICS IN THE REJU KHAL RIVER

Hydrobiological characteristics determine the health of an aquatic ecosystem. Reju Khal estuary on the subtropical coasts is among the major estuarine system in Bangladesh. Monitoring the water characteristics and fish diversity of this estuary is very important due to its ecological and economical services provided to the coastal areas. Consequently, the present study investigated the occurrence and abundance of the ichthyofaunal assemblages and hydrobiological characteristics (temperature, pH, salinity, dissolve oxygen, total dissolve solids, sechi depth, phytoplankton and zooplankton abundance) from December 2012 to August 2013. The ranges of the hydrobiological factors were 16-26C for surface water temperature, 7- 8 for pH, 8-29 PSU for salinity, 3-4 mg/L for dissolved oxygen (DO), 33- 35 mg/L for total dissolved solids (TDS), 21-45 cm for sechi depth, 27-45 individuals/m3 for zooplankton abundance and 9400-17100 cells/L for phytoplankton abundance. Overall, 6706 individuals of the faunal population comprised of 36 species from 23 families were captured. The species recorded during the study are the representative of the subtropical coasts. The similarity percentage analysis (SIMPER) suggested that Stolephorus indicus was found to be the most contributory species followed by Mugil cephalus and Mystus gulio. The results of this study will be helpful for management and planning for water quality monitoring in this estuary. It is suggested that frequent monitoring of the hydrobiological recourses of the estuarine systems is very necessary in near future to detect the shifting of baselines, assisting ecosystems-based monitoring and enhancing restoration efforts