Relationships of euglenophytes bloom to environmental factors in the fish ponds at Rajshahi, Bangladesh

The study was conducted to investigate the relationships of euglenophytes bloom to environmental factors in the fish ponds at Rajshahi, Bangladesh for twelve months from July 2010 to June 2011.Among the study ponds, three ponds with bloom were located at Raighati, Mohanpur Upazila (BP-R), another three ponds with bloom at Yusufpur, Charghat Upazila (BP-Y) and three non-bloom ponds (NBP) at Meherchandi, Motihar Thana.The environmental factors (water temperature, DO, pH, NO 3 -N, NH 4 -N, PO 4 -P, Fe, Zn, Mn and Cu), soil organic matter, and algal community and density were examined monthly by using standard methods.There was no significant difference in water temperature among BP-R, BP-Y and NBP but significantly lower DO and pH, higher concentrations of NO 3 -N, NH 4 -N, PO 4 -P, Fe, Zn, Mn, Cu and soil organic matter and higher density of euglenophytes were recorded in BP-R and BP-Y as compared to NBP (P<0.05).The euglenophytes were composed of three genera, Euglena, Phacus and Trachelomonas among which Euglena (E.sanguinea) was highly dominant.The density of euglenophytes in BP-R and BP-Y showed an increasing trend from September (early autumn) and peaked in November (late autumn) and December (early winter).The density of these algae was negatively correlated with water temperature, DO and pH while positively correlated with NO 3 -N, NH 4 -N, PO 4 -P, Fe, Zn, Mn and Cu concentrations (P<0.05).