Abstract This research was carried out from December 2020 to January 2021 in Carocok Tarusan Waters, Pesisir Selatan Regency, West Sumatra, which aims to analyze the concentration of nitrate, phosphate and silicate, calculate the abundance of planktonic diatoms and analyze the relationship between the content of nitrate, phosphate and silicate to the abundance of planktonic diatoms presen…