The Effect of River Lesser – Zab on the Phytoplankton of River Tigris, Iraq

Thaer I. Kassim, Anmar W. Sabri, Suad K. Salman


Three localities were selected in Lesser – zab and Tigris rivers to collect water samples monthly during the period between January to October 1999. Total cell counts of phytoplankton and its chlorophyll – a concentration was determined. A total of 231 taxa were identified and 41 species of which new record to Iraq. Bacillariophyceae was dominated especially the pennate types. Followed by chlorophyceae and cyanophyceae. The other classes were very spare and did not affect the total cell counts. Few species comprised as more than 10% of the total counts (Stephanodiscus astrea, Cyclotella ocellata, Achnanthes minutissima, Cymbella kutzingiana). Both species S. astrea and C. ocellata were dominated in Lesser – zab and added a large number of cells to the river Tigris. Lower cells in the number of phytoplankton in the river Lesser – zab were recorded, so it has shown a dilution effect on the phytoplankton population density of the river Tigris during most of the study period.


Phytoplankton, Rivers, Tigris, Lesser-zab

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