Structure Community PhytoplanktonIn Cikidang River, Pangandaran City, Indonesia

This research aims to determine the structure of the phytoplankton community in the waters of the Cikidang River, which can use as a bioindicator of water quality. The research began in November 2021-February 2022 using a survey method. Sampling does at four stations. The determination of the stations does by considering land use and river orders. The water parameters analyzed are transparency, temperature, Salinity, pH, Carbon Dioxide (CO2), Biochemical Oxygen Demand (BOD), Dissolved oxygen (DO), Nitrate (NO3-), Phosphate (PO43-), Nitrate NH3, phytoplankton abundance, diversity index, and dominance index. The results showed the identification of 21 genera from 6 classes and four phyla such as Chrysophyta, Cyanophyta, Chlorophyta, and Euglenophyta. Abundances index ranging from 17.2-104.6 Ind/L. The diversity index ranged from 0.49 to 0.72. At the same time, the dominance index ranges from 0.28 to 0.51 and belongs to the category of low to moderate dominance. The water quality in the Cikidang River generally meets the requirements of class II and Class III quality standards, according to Government Regulation 22 of 2021 concerning Water Quality Management and Water Pollution Control.