Study of phytoplankton biology index and water quality parameters of kali Surabaya River

Phytoplankton is used as an indicator of water quality because of its short life cycle and fast response to changes in the aquatic environment, especially in river ecosystems. In addition, the existence of industrial, agricultural, and community activities around the river will cause changes in the water quality of the waters. This study aim was to analyze the distribution of the phytoplankton community based on the biological index related to the water quality parameters of the Kali Surabaya river. The study was carried out in January - February 2021. The study sample used a random sample method which was divided into four observation station. The samples obtained were identified by the type of phytoplankton and tested for water quality parameters (pH, temperature, brightness, strong currents, dissolved oxygen, biological oxygen demand, nitrate, phosphate, and chlorophyll-a). The results showed the phytoplankton abundance index in the Kali Surabaya river is low with a range of 485,49-626,21 cell/L, the diversity index (H') is moderate with a range of 1.446-1.703, uniformity index (E) in the range of 0,61-0,626, and dominance index (D) with a range of 0,293-0,368. The relationship between the biological index of phytoplankton with the water quality of the Kali Surabaya River that the water quality parameters that had more influence on the diversity index, uniformity index, and dominance index were pH, dissolved oxygen, and nitrate.