Diatoms in Drift – A Preliminary Study in Northern Oman

This first paper on the freshwater diatoms of Oman records 49 species belonging to 17 genera in the stream drift of 13 man-made irrigation channels known as aflaj. The number of species in each genus ranged from 1 to 7.  Pennales were represented by 16 genera and 47 species while centrales had two species in one genus. The number of species drifting in each aflaj ranged from 1 to 15. Only one species occurred in 59% of the localities sampled; two species occurred in 29%; and the occurrence of other species ranged from 6 to 24%. Although all aflaj originated from springs in the northern mountain region with the same underlying geology, there were differences in the surface water chemistry, but the diatom assemblages could not be characterised based on the physical and chemical parameters. All aflaj investigated largely satisfied the standards of drinking and irrigation water quality in Oman. Therefore, the diatom assemblages reported here can be considered as those of clean water. Similarity coefficients based on diatom flora indicated that all aflaj were significantly dissimilar. The need for further studies on the freshwater microflora of Oman is emphasized.