Preliminary survey of edaphic algae in Al-Hasa region, Saudi Arabia.

Five soil samples were taken from different cultivated sites from the North Villages of Al-Hasa. Three algal groups were recorded throughout this study, Bacillariophyta, Cyanophyta and Chlorophyta. Fifty-two genera of algae were identified in all the soils sampled during this investigation. Out of these, 11 genera belonged to the Chlorophyta; 16 genera belong to Bacillariophyta and 25 genera to Cyanophyta. Penniate Bacillariophyta (Nitzschia, Gyrosigma), oscillatorid Cyanophyta (Osillatoria, Phormidium, Nostoc and Anabaena) and coccoid Chlorophyta (Ankistrodesmus falacatus, Chlorella ellipsoidea, Chlorella vulgaris, Gleocystis bcillus, Scenedesmus acuminatus, Scenedesmus arvensis and Scenedesmus bijuga) were the predominant in all investigated sites.