Seasonal Variation of Phytoplankton in AL-Diwaniya River

This study was conducted from January to October 2014, the samples were collected monthly from four stations in AL-Diwaniya River at AL-Diwaniya city. Phytoplankton species which are diagnosed during study period are (506) and the numbers of common types in four sites are (61). Bacillariophyceae is dominate on other classes and Chlorophyceae, Cyanophyceae, Dinophyceae then Chrysophyceae and Euglenophyceae. The study shows that there are (150), (144), (118) and (94) species in the first, second, third and fourth sites. The species that have highs numbers are (Achnanthes, Cymbella, Nitzschia, Navicula). Other types are dominant in their existence and number during study period (Cycltella comta, Cylotella Ocellata, Cycletella meneghiniana, Cyleotella Kutzingana, Pediastrum somplex, Diatoma elongatum and Cocconeis Placentula) During the study period, there are seasonal and site changes in total number of phytoplankton which ranged between (440.61-2994.3 cell×10^3/L).