An Ecological Study on the Beel Joshi (Rajshahi District), Northern Bangladesh

The present study has been made on the assesment of ecological aspects of a beel, Joshi covering an area of 630 ha in the Rajshahi district, Northern part of Bangladesh. Surface run-off and increase in flow of rain water from the upper stretch during monsoon cause inundation and resumption of connection between beel and parent rivers. The range of Dissolve Oxygen (DO) content (5.26-6.08 mg L-1) and pH (7.5-8.2) were found. Lower values of total hardness and total alkanity indicated fewer nutrients in the beel water. Free CO2 was relatively high in this beel. Phytoplankton diversity in the beel represented by 4 groups viz. Myxophyceae, Chlorophyceae, Bacellariophyceae, Euglenophyceae in order of abundance. A total of 73 fish species belonging to 45 genera 21 families and 1 species of prawn were identified so far from the beel. A total of 14 types fishing method were found in operation. Seine nets (moshari berjal, shono berjal) and gill net (current jal) were identified as detrimental gear killing juveniles of different species during post-spawning period. Kua fishing was also found harmful due to dewatering nature. A total of 12 species of aquatic weeds were identified from the beel. The eggs of Macrobrachium lameri were also detected during the study period.