Study of the Biological Diversity of Benthic algae in the Tigris River, Baghdad - Iraq

The present work included a study of benthic algae on two substrates: rocks and clay on a section of the Tigris River at the Al-Atifiyah site in the fall of 2018. The result of this study was recorded 89 species belong to 50 genus of benthic algae on both substrates and composed of Bacillariophyceae (59.6%, 61.2%), Chlorophyceae (25.8%, 20.4%) and Cyanophyceae (14.5%, 18.3%) respectively on epilithic and epipelic algae. The present study was recorded the highest total algae cell density (1173.2 cells *103/cm2) on epilithic algae while the lowest total algae cell density was recorded on epipelic algae (76.95 cells *103/gm). For measure diversity, four indices of diversity are used: Margalef index, Shannon and Weaver Index, Evenness Index and Simpsons Index. The study showed that benthic algal communities are of high diversity with different distribution and spread of adherent algae on different natural surfaces in the aquatic environment. 62 species of epilithic algae were recorded belonging to 39 genus, while epipelic algae were recorded 49 species belonging to 34 genus. Bacillariophyceae was recorded the highest number of species compared with other classes of benthic algae (59.6%, 61.2%) respectively on epilithic and epipelic Chlorophyceae recorded second ordered after diatoms in importance 25.8%, 20.4%, Cyanophyceae recorded third orders 14.5%, 18.3% respectively on epilithic and epipelic algae.