Water quality variation and algal succession in commercial hybrid catfish production ponds

Abstract

This study on water quality variation and algal succession in commercial hybrid catfish production ponds was conducted in 2007 in Bang Pa-In district, Ayutthaya province, Thailand. The study covered two fish crops, May-August and September-December. The physico-chemical water quality in the catfish ponds changed dramatically over the study period due to the practices of water changing, lime application and the culture duration before harvesting. Samples of algae collected during the first crop period contained 83 species belonging to the following divisions: Chlorophyta (34 species), Cyanophyta (28 species), Euglenophyta (12 species), Bacillari ophyta (6 species), Chrysophyta (1 species), Pyrrhophyta (1 species) and Cryptophyta (1 species). Samples collected during the second crop contained 60 species of the following divisions: Chlorophyta (28 species), Cyanophyta (16 species), Euglenophyta (10 species) and Bacillariophyta (6 species). Cyanophyta was the most abundant in both crops, followed by Chlorophyta, Euglenophyta, Bacillariophyta, Chrysophyta, Cryptophyta and Pyrrhophyta. The blue-green algae Microcystis increasingly dominated the algal population during the course of the culture period. Pseudanabaena spp. were succeeded by Oscillatoria spp. and then Microcystis spp. in the first crop. Microcystis spp. dominated during the first two months of the second crop, and then was succeeded by Planktolyngbya spp. and Nitzschia spp. in the third and fourth months. In summary, water quality may account for algal proliferation resulting in algal blooms and influence algal succession in commercial catfish production ponds. © 2012 by Maejo University, San Sai, Chiang Mai, 50290 Thailand.