The Effect of Plankton Community Structure in Tributaries at the Downstream of the Musi River, Palembang

Abstract

River condition is influenced by both natural and human activities. The tributaries also affect the condition of water in the river. The Musi River is the largest in South Sumatra. Its condition is influenced by its nine major tributaries and other rivers. This research applied the descriptive method. Conducted at the five tributaries of the Musi River, this research aimed: 1) to calculate the plankton abundance (N), evenness index (E), the diversity index (H’), and dominance index (D); 2) to perform a correlation test; 3) to perform ANOVA; 4) to perform factor analysis using PCA (principal component analysis). Bacillariophyceae abundance was the highest among other genera, followed by Chlorophyceae, Flagilariophycea, Euglenida, and Chrysophyceae. Crustacea had the highest abundance in the zooplankton class, followed by Tubulenia, Maxillopoda, Mastigophora, and Imbricatea. Plankton's diversity and community stability levels were regarded as moderate; as there was no domination found, the water was classified as heavily polluted. According to the ANOVA hypothesis, the five tributaries' phytoplankton and zooplankton data groups showed different variations. The abundance of phytoplankton was influenced by three factors reaching 76.54%. The condition was indicated by bioindicator pollution: Nitzchia, Chlorococcum, Euglena, Oscillatoria, and Spirogyra. The waters were categorized as Mesotrophic waters, indicating a moderate level of water fertility. At a low pH value, as the diversity index became low, the abundance of phytoplankton also became low. The polluted condition was also shown by the low diversity, which indicated an unstable ecosystem. These waters could only be used for irrigation. The moderate fertility of the waters and its level of contamination affected the downstream Musi River. Proper water management is required to maintain the environmental sustainability. Any parties associated with water management should take steps to improve the water condition downstream of the Musi River.