Determination of water quality and trophic level by using epilithic diatoms in Büyükçekmece Reservoir

OpenAlex İngilizce

In this study, the composition, distribution, and seasonal changes of epilithic diatoms were investigated to reveal the water quality and trophic level of Büyükçekmece Reservoir, which is one of the essential freshwater sources for İstanbul, Türkiye. Water and diatom samples were collected on the same day from all stations, and sampling was only on one day for a specific sampling season. Seventy-six taxa belonging to 30 genera were identified, two of which were centric and 74 were pennate diatoms; 12 of the epilithic species were newly-reported diatoms for the Büyükçekmece Reservoir. The highest number of epilithic diatom species was obtained in November, and the lowest was in February. According to relative abundance, Gomphonella olivacea was abundant in February, Cymbella lange-bertalotii in May, and Cocconeis placentula in August and November. According to the diatom-based water quality indices, the Büyükçekmece Reservoir belongs to I (very good, oligotrophic) and II (good, meso-oligotrophic) water quality classes. Redundancy analysis was used to reveal the association of epilithic diatom species with ecological variables, and it was determined that Silicate-Si, Ammonium-N, and temperature were the most effective variables in the distribution of epilithic diatoms.