Phytoplankton Community Structure as Bioindicator of Water Quality in Floating Net Cage Area with Different Density at Cirata Reservoir

Cirata Reservoir is built with water sources originating from the Citarum River. Cirata Reservoir mainly use as a hydroelectric power plant and fish cultivation area with a floating net cage system. The utilization of a reservoir for the cultivation of fish in the Cirata Reservoir had exceeded the specified capacity by the government. That matter had caused the water quality to change in waters of the Cirata Reservoir. Phytoplankton is the first organism that is affected because the degradation of water quality. The purpose of this research is to determine the structure community of phytoplankton in floating net cage areas with different density and water flow at Cirata Reservoir. This research was conducted on November 16 - December 8 of 2019 in the Cirata Reservoir with sampling station located at Jangari, Meleber, and Patokbeusi. The method that was used in this research was purposive sampling method. The result of physic-chemical parameter of this research showed that temperature at all station ranged between 31,9-34,5°C, transparency 53,5-76 cm, pH 6,87-7,67, CO2 8,4-16,8 mg/L, BOD5 1,1-20,5 mg/L, DO 5,83-9,72 mg/L, nitrate 0,169-0,241 mg/L, ammonia 0,001-0,241 mg/L, and phosphate 0,131-0,195 mg/L. The result of phytoplankton community structure indicated that composition of phytoplankton had 30 genera with Chlorophyceae class as the most dominant. The abundance of phytoplankton during research was ranged between 49.570-338.450 ind/L, diversity index 0,78-0,88, domination index 0,12-0,22, and saprobic index 1,04-1,59. Saprobic index indicated that water in each station was included in mild to moderate pollution category or in the β-Meso/ oligosaprobic phased which was showed by the large number of Gloeocystis and Glenodinium genera.