Kristina Marsela, Herman Hamdani, Zuzy Anna, Heti Herawati
Citarum River is the longest river in West Java Province, it is utilized for various anthropogenic activities that will affect the water quality, ecological state, and parameters of nitrates and phosphates in the waters of Citarum River. Nitrate and phosphate content can affect Phytoplankton abundance. Phytoplankton is a bioindicator to determine water quality. The purpose of this study is to determine the association of nitrates and phosphates with the abundance of phytoplankton and determine the quality of water in the Citarum River. The study began in August 2020 until September 2020. The research uses a survey method with a purposive sampling technique. Sampling was carried out at 5 stations with 5 times repetitions every 7 days. The water parameter analyzed are transparency, temperature, current, pH, DO, BOD, PO42-,NO3–, Phytoplankton abundance, diversity index, and dominance index. Results showed that phytoplankton in the citarum river there were 24 genera divided into 4 phylum. Diversity index during the study reached between 0,91 – 0,99 and dominance index was in the range 0,01 – 0,2. Phytoplankton abundance ranges from 11 to 1292 ind/L. The highest genera phytoplankton composition at each station was found is Synedra as much as 1087 ind/ L. Nitrate content ranges from 0.13 – 0.33 mg/l and phosphate content range from 0.13 – 0.29 mg/l. The acquisition of R square value based on the simultaneous analysis of the relationship between nitrate and phosphate and the abundance of phytoplankton was 43,9% and 56,1% was influenced by other several factor namely temperature, water transparency, nutrient, and water flow.