Microalgal ecology in experimental carp - pangas polyculture ponds

Microalgal ecology was studied for a period of 18 weeks from 15 June to 18 October 2003 in experimental carp - pangasiid catfish polyculture ponds under four different stocking rates (treatments: T) each with three replications in the Field Laboratory of the Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh. The ponds were dried, limed (CaO) at the rate of 247 kg/ha and exposed to sunlight for about two weeks. Urea, super phosphate and cowdung were applied 7 days before stocking of fish fingerlings and then at 10 days interval at the rates of 24.70 kg/ha, 24.70 kg/ ha and 617.50 kg/ha respectively. A total of 34 microalgal genera were identified under four major groups. Some water quality parameters e.g. temperature, transparency, pH, depth and nutrients (NO3-N and PO4-P) were recorded at regular intervals and their relationship with the occurrence and abundance of microalgae were studied. The highest microalgal cell density was found during 16th week (4 October) in all of the treatments corresponded with high nutrient concentrations (NO3-N and PO4-P). Chlorophyceae was the most dominant group followed by Cyanophyceae, Bacillariophyceae and Euglenophyceae except in T4 where Cyanophyceae was dominant. Dissolved oxygen (4.2 to 9.6 mg/I), pH (7.0 to 8.1), temperature (30.2 °C to 32.6 °C), NO3-N (0.46 to 1.38 mg/I) and PO4-P (0.83 to1.73 mg/I) were favourable both for microalgal and fish growth.

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Journal of the Bangladesh Agricultural University, 06, 1
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 Record created 2018-09-24, last modified 2020-10-28

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