Nutrient availability, especially nitrates and phosphates, is very influential to phytoplankton abundance in water. Nitrate and phosphate are the constituent components of proteins for growth and photosynthesis. The high anthropogenic activities in the Segara Anakan environment increase both nutrients. This study aimed to examine nitrate and phosphate, as an indicator of water fertility, in affecting phytoplankton abundance. Data were obtained in April and May 2018. Water and plankton samples were carried out by purposive sampling. The results showed nitrate concentration of seven stations ranging from 3.06–5.32 mg/L. Phosphate concentration was between 0.13 mg/L and 0.18 mg/L, while the phytoplankton abundance reached 21–269 individuals/L. Based on the criteria of phytoplankton abundance, the eastern part of the Segara Anakan was classified under the oligotrophic category.

Diana Retna Utarini Suci Rahayu

Agatha Sih Piranti

Erwin Riyanto Ardli

Nuning Setyaningrum Setyaningrum

Ilalqisni Insan Insan

Dwi Sunu Widyartini

Carmudi Carmudi