Water quality assessment of the Pazarsuyu Stream based on epilithic diatom communities

Abstract

The trophic diatom index (TDI) and the biological diatom index (BDI) provide information about the trophic levels in the aquatic ecosystem. The pollution tolerance index (PTI) and saprobic index (SI) use diatoms to assess the health of aquatic ecosystems. We collected epilithic diatoms from the Pazarsuyu Stream located in the Turkish province of Giresun between June 2014 and May 2015 to assess the water quality using the four types of diatom indices which consist of BDI, TDI, PTI, SI. A total of 49 taxa were identified as belonging to the class of Bacillariophyceae. The reference site affected by domestic waste contained Ulnaria ulna (Nitzsch) Compère, Navicula radiosa Kützing and Encyonema minutum (Hilse) D. G. Mann. The water quality of the site had average BDI values ranging between 14.2 and 14.5 and average TDI values between 50 and 54.7, both of which indicate the existence of a mesotrophic environment. However, according to the value of the SI, the studied site was moderately polluted (β-mesosaprobity), whereas PTI values showed that the site was heavily polluted (α-mesosaprobic).