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.
Jahan
Roksana
R
Department of Fisheries Management, Bangladesh Agricultural University, Mymensingh, Bangladesh.
Khan
Saleha
S
Haque
Md Mahfuzul
MM
Choi
Joong Ki
JK
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