عنوان مقاله [English]
Different N: P ratios and varying phosphorus concentrations were considered based on the logarithmic calculations and the effects of these factors on cyanobacterial bloom of Nostoc sp. were inspected. The study was performed in situ while the temperature and light intensity were kept at 25±2oC and 3500±350 lux respectively. The laboratory tests lasted 96 hours. Zinder media was used as the control medium however different N: P ratios and P concentrations were applied as treatments. Visual counting at the start and end of the experiments were carried out to assess the growth percentage. The results showed that phosphorus concentrations in Zinder media (2.96 mg.L) are the optimum value for Nostoc bloom. Nostoc achieved its optimum growth at the range of 2.5N: 1P to 10N:1P. The maximum level of growth percentage was reached to 3497.17±746.18 percent in 4N: 1P ratio with 11.84 mg.L of nitrogen and 2.96 mg.L of phosphorus. The bloom was eliminated at 145.27: 1. The whole results confirmed that in the presence of enough nitrogen and phosphorus concentrations with low N: P ratio, the maximum bloom intensity observes.