University of Tehran Journal of Natural Environment 2008-7764 73 4 2021 02 19 Biodiversity of Diatoms in Khormarud River, Golestan Province Biodiversity of Diatoms in Khormarud River, Golestan Province 625 636 80387 10.22059/jne.2021.304839.2018 FA Abdolkarim AgAtabay Department of biology faculty of basic science Gonbad Kavous university Jamileh Panahy Mirzahasanlou Assitant Prof. Department of Biology, Faculty of Basic Science, Gonbad Kavous University, Gonbad Kavous, Iran Faramarz Rostami Charati Research Center for Conservation of Culture Relics (RCCCR), Research institute of Cultural Heritage & Tourism Reza Akbari Department of Chemistry, Faculty of Basic Science Gonbad Kavous University Journal Article 2020 06 26 Khormarud is one of the Rivers in Azadshahr County in Golestan Province, which is originates from southeast elevations and discharges to the Gorganrud River that reach to the Caspian Sea. Diatoms constitute the dominant algal flora in aquatic ecosystems. In order to identifying diatom flora of Khormarud River, specimens were collected from stony and sediment substrates during summer and autumn of 2017. In total, 60 species belong to 32 genera and 20 families were identified, from which 59 species were belonging to class Bacillariophyceae and only one species to class Coscinodiscophyceae. Nitzschia with 7 species were the most species rich genus and Navicula and Gomphonema with 5 sp. were in the next order. The most abundant taxa were Achnanthidium gracillimum, Achnanthidium nanum, Cocconeis placentula, Cymbella affinis, Encyonopsis minuta, Gomphonema olivaceum and Nitzschia inconspicua. According to the results of diversity indices, site 3 which affected by runoff from fishery activities, had lowest species diversity and high pollution level. In total epipelic samples in all sites had high diversity than epilithic samples which could explain by the fact that algae on sediments are affected weakly by water column chemistry than epilithic algae. Khormarud is one of the Rivers in Azadshahr County in Golestan Province, which is originates from southeast elevations and discharges to the Gorganrud River that reach to the Caspian Sea. Diatoms constitute the dominant algal flora in aquatic ecosystems. In order to identifying diatom flora of Khormarud River, specimens were collected from stony and sediment substrates during summer and autumn of 2017. In total, 60 species belong to 32 genera and 20 families were identified, from which 59 species were belonging to class Bacillariophyceae and only one species to class Coscinodiscophyceae. Nitzschia with 7 species were the most species rich genus and Navicula and Gomphonema with 5 sp. were in the next order. The most abundant taxa were Achnanthidium gracillimum, Achnanthidium nanum, Cocconeis placentula, Cymbella affinis, Encyonopsis minuta, Gomphonema olivaceum and Nitzschia inconspicua. According to the results of diversity indices, site 3 which affected by runoff from fishery activities, had lowest species diversity and high pollution level. In total epipelic samples in all sites had high diversity than epilithic samples which could explain by the fact that algae on sediments are affected weakly by water column chemistry than epilithic algae. https://jne.ut.ac.ir/article_80387_c07e75871ea2195931827184008ed97b.pdf