Effect of Hydraulic Flow on Phytoplankton Population Structure in Tajan River

The aim of present study was to investigate the relationship between hydraulic and ecological variables of the studied span and to investigate changes in living conditions of phytoplankton (Amphora ovsalis and Navicula placentula). According to the measurements and analysis of habitat fit curves, it can be concluded that the highest frequency of Amphora ovsalis and Navicula placentula occurred and specified at flow rate of 15.82 and 14.942 m3/s, respectively. As can be seen, the lowest frequency of Amphora ovsalis and Navicula placentula in this measurement occurred at flow rate of 15.355 and 5.289 m3/s, respectively. The best habitat conditions for Amphora ovsalis and Navicula placentula are in the range of 0.18 -0.31 and 0.18 - 0.265 of Froude number range respectively. The highest density and abundance of Amphora ovsalis and Navicula placentula was observed in the range of 0.017 - 0.055 and 0.017 -0.039 mg/l of phosphate demonstrating that the best growth and living conditions are predisposed in this range for these species had suitable habitat conditions for life in this range. The highest frequency of Amphora ovsalis and Navicula placentula is in the range of 0.019 - 0.071 and 0.047-0.071 mg/l nitrite, respectively. Amphora ovsalis and Navicula placentula had the highest frequency when nitrate ranges 4.48 – 5.16 and 4.48- 5.37 mg/l. The best habitat conditions for Amphora ovsalis and Navicula placentula were between the mean velocity values in the range of 1 -1.2 m/s.