Study of the genera Encyonema, Craticula, and Cymatopleura (Bacillariophyta) in the western rivers of Lake Urmia, Iran

This study is the first attempt to investigate some diatom species in the western rivers of Lake Urmia. The study presents the details of Encyaonema, Craticula, and Cymatopleura at the lowest taxonomic level to provide information in terms of species taxonomy, morphology and ecology. In order to determine the morphological similarities in species level of the aforementioned genera, 14 sites were repeatedly sampled along the rivers from September 2021 to August 2022. The results showed a high diversity of diatoms including Encyonema caespitosum. Encyonema silesiacum, Encyonema prostratum, Craticula cuspidata, Craticula ambigua, Cymatopleura solea, Cymatopleura apiculata, Cymatopleura hibernica and Cymatopleura elliptica. The taxonomic and ecological study of the observed species from the western rivers of Lake Urmia indicates diatom assemblage closely integrated with the limnology and ecological status of the rivers. Indeed, the results infer that the rivers undergo a transition from freshwater to brackish, particularly where the rivers terminate at Lake Urmia.