A study on the water quality of Derinçay Stream (Çorum) based on phytoplankton and phytobenthos

In this study, monthly samples were taken from 6 stations determined on the stream between August 2020 and July 2021 to determine the phytoplankton and epiphytic diatoms of Derinçay Stream (Çorum). The samples were counted and identified, and the seasonal changes of the algae were determined. In the study, a total of 91 taxa belonging to the divisions Bacillariophyta (46), Euglenozoa (17), Cyanobacteria (14), Chlorophyta (7) Charophyta (4), Miozoa (2) and Cryptophyta (1) were identified in the phytoplankton flora. The algae group with the highest number of organisms in Derinçay Stream phytoplankton is Bacillariophyta, followed by Cyanobacteria and Euglenozoa. In epiphytic diatoms, 42 taxa belonging to 12 orders of Bacillariophyta division were identified. Within the Bacillariophyta division, the dominant algae order was the Naviculales team, which includes 12 taxa. In addition, physicochemical analyzes of the water samples taken from the stations were made, and the relationship between the obtained data and the detected organisms was tried to be determined. Diversity, regularity, frequency, similarity and NMDS analyzes of phytoplankton and epiphytic diatoms were made, and their water quality indicator status was determined. In addition, the Phytoplankton Community Index (Q(r) index) of the phytoplankton species and the Trophic Diatome Index (TDI) of the epiphytic diatoms were calculated, and the water quality was tried to be determined by using the indicator characteristics of the species identified in the study area. According to the phytoplankton community index (Q(r) index) results, it was determined that Derinçay Stream is in the "poor" ecological water quality class. The fact that the species belonging to the Oscillatoria and Euglena genera, which are used as indicators to determine the degree of pollution in the waters in our study area, were found in all stations, supported the high pollution level of the stream in our research area. According to Shannon diversity index, it has been seen that the stream is in the "Poor" ecological quality status and "Oxygen-Free-Highly Polluted" pollution class. In addition, it has been observed that tolerant species that can live in polluted waters are common in phytoplankton and epiphytic flora. According to the results of the Trophic Diatom Index (TDI) calculated on the epiphytic algae in phytobenthos, Derinçay Stream has been determined to have a hypertrophic ecological status corresponding to the "bad" water quality class. When the data in the study area are evaluated, it is seen that Derinçay Stream is facing the threat of pollution. In order to protect the aquatic ecosystem of Derinçay Stream, the wastewater treatment plant on the stream should be transformed into a modern and biological treatment facility and the polluting factors of the stream should be kept under control.