Assessment of Seasonal Waters Quality Based on Abundance, Diversity, and Domination of Phytoplankton in Bajulmati Reservoir

Water quality assessment can be carried out through physical, chemical, and biological analyses. Phytoplankton is a biological microorganism that is usually used as indicators to assess surface water quality, specifically primary productivity. Bajulmati Reservoir is located in Banyuwangi, East Java, which functions as irrigation for agricultural and fisheries land. The purpose of this study was to analyze the productivity of reservoir waters based on phytoplankton abundance. The method used is purposive sampling with four sampling point stations from the entire reservoir area. The phytoplankton found were nine genera, consisting of 5 genera from the Cyanophyceae class, and one genus from each class, namely the Chlorophyceae, Bacillariophyceae, Euglenophyceae, and Dinophyceae classes. The productivity of the Bajulmati reservoir is included in the eutrophic category, with an average abundance of phytoplankton of 15.215 ind.L-1. Meanwhile, the diversity index shows that the distribution of stable individuals and communities is low, namely 0.87. Despite this, the Cyanophyceae class is dominating with the dominance index was 0.52.