Study of harmful algal blooms in a eutrophic pond, Bangladesh.
The purpose of this research was to analyze the underlying mechanisms and contributing factors related to the seasonal dynamic of harmful algal blooms in a shallow eutrophic pond, Bangladesh during September 2005-July 2006. Two conspicuous events were noted simultaneously throughout the study period: high concentration of phosphate-phosphorus (>3.03; SD 1.29 mg l(-1)) and permanent cyanobacterial blooms {>3,981.88×10(3) cells l(-1) (SD 508.73)}. Cyanobacterial blooms were characterized by three abundance phases, each of which was associated with different ecological processes. High nitrate-nitrogen (>2.35; SD 0.83 mg l(-1)), for example, was associated with high cyanobacterial abundance, while low nitrate-nitrogen (0.36; SD 0.2 mg l(-1)) was recorded during moderate abundance phase. Extremely low NO3-N/PO4-P ratio (>3.55, SD 2.31) was recorded, and all blooming taxa were negatively correlated with this ratio. Cyanobacterial blooms were positively correlated with temperature (r=0.345) and pH (0.833; p=0.05) and negatively correlated with transparency (r=-0.956; p=0.01). Although Anabaena showed similar relationship with water quality parameters as cyanobacteria, the co-dominant Microcystis exhibited negative relationship with temperature (r=-0.386) and nitrate-nitrogen (r=-0.172). This was attributed to excessive growth of Anabaena that suppressed Microcystis's growth. Planktothrix was the third most dominant taxa, while Euglena was regarded as opportunistic.
Department of Fisheries Management, Bangladesh Agricultural University, Mymensingh, Bangladesh.
Roksana
R
Jahan
Saleha
S
Khan
Md Mahfuzul
MM
Haque
Joong Ki
JK
Choi
D017756:Aquaculture; D001459:Bangladesh; D044822:Biodiversity; D000458:Cyanobacteria / Q000254:growth & development; D005618:Fresh Water / Q000737:chemistry*; D057097:Harmful Algal Bloom; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000032:analysis; D010710:Phosphates / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D010839:Phytoplankton / Q000145:classification / Q000254:growth & development*; D012621:Seasons; D014874:Water Pollutants, Chemical / Q000032:analysis
D009566:Nitrates; D010710:Phosphates; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D009584:Nitrogen