ECOLOGICAL EFFECTS OF BELIK RIVER HYDRAULIC CHARACTERISTICS ON PERIPHYTON COMMUNITY AS WATER QUALITY BIOINDICATOR

Belik River is one of urban rivers in the Special Region of Yogyakarta, which has hydrological problems both in quantity and quality. These problems triggered the construction of various types of channel modifications. This study aimed to identify water quality and the ecological effects of channel modifications based on the presence of periphyton communities as water quality bioindicators. Sampling was carried out in January 2021 and March 2021. Samples were taken from 4 sampling sites having different channel characteristics with 3 repetitions at each location. The physicochemical parameters measured included pH, detergent, nitrate, sulfate, total phosphate, TSS, TDS, DO, CO2, water temperature, depth, transparency, discharge, current velocity, and yearly rainfall data. Ninety-one (91) periphyton species dominated by Nitzschia improvisa, Nitzschia terricola, and Nitzschia philippinarum werefound in January 2021, higher than the 61 species of periphyton dominated by Nitzschia improvisa found in March 2021. Results of the Canonical Correlation Analysis (CCA) indicated that the distribution and abundance of periphyton in Belik River were influenced by CO2, total phosphate, discharge, DO, nitrate, TSS, and depth. The Shannon-Wiener Diversity Index showed that water quality in January 2021 decreased compared to March 2021. Results of the cluster analysis showed differences in water quality and abundance of periphyton found in the four types of river channels. It can be concluded that differences in hydraulic characteristics affected water quality and the ecological health of Belik River.