Investigation of biodiversity and frequency of diatoms and their relationship with water quality in the River Ahar chay, NW-Iran

Algae are one the most important bio-indicators for evaluation of water quality in rivers and wetlands. Diatoms (Bacillariophyaceae) are unicellular eukaryotic algae. Having the frustule is one the important characteristics in this group of the algae. Diatoms are living in freshwater and brackish water, where their growth and development are affected by water chemistry and quality (temperature, salinity, habitat, light, …). This study was focused on the diatom flora of the River Ahar chay and the effects of the ecological factors on biodiversity and frequency. In order to study, the samples were collected in ۶ sites during four different seasons in ۲۰۱۹-۲۰۲۰. In this study, physicochemical factors such as PH, DO, EC were measured. After the transferring the samples to the laboratory, the samples were digested using H۲O۲ and HCl. Then, standard slides were prepared using Naphrax glue. Diatoms were identified using light microscope and diatom flora. Moreover, the frequency of the diatom community was measured. This investigation showed that species such as Surirella angusta, Nitzschia dissipata, Rhoicosphenia abbreviate were dominant whilst in downstream of the river species such Gomphonema truncatum, Nitzschia palea, Cyclotella meneghinina were dominant . The data used to calculate the Trophic Diatom Index and the results showed that the up-stream of the river is in good ecological status whilst the down -stream of the river is in mediate to poor conditions.

کلیدواژه ها:

Diatom ، EC ، DO ، frustule ، Bacillariophyaceae ، River Ahar chay ، Ecology