Community Structure and Saprobic Index of Plankton in the Air Bengkulu River

The quality of the Air Bengkulu River has deteriorated due to industrial activities and community activities within the Air Bengkulu watershed, negatively impacting the plankton community structure. This study aims to analyze the plankton community structure and determine the pollution level in the Air Bengkulu River using the saprobic index. The research was conducted in the Air Bengkulu River from January to March 2023. Sampling stations were selected using purposive sampling based on landscape differences. Samples were collected at three stations, with 10 sampling points at each station. Data analysis included plankton abundance, diversity, evenness, dominance, similarity, and saprobic indices. The results showed that 62 species of plankton in the Air Bengkulu River, of which 20 species Bacillariophyceae class, 19 species Chlorophyceae class, 5 species Euglenophyceae class, 6 species Cyanophyceae class, 9 species Monogonanta class, 2 species Hexanauplia class and 1 spesies Maxillopoda. The highest plankton abundance was observed at Station I with 1.322 individuals/liter, followed by Station II with 973.2 individuals/liter, and the lowest at Station III with 811.2 individuals/liter. Diversity was high, evenness was high, and dominance was low at Station I (H’ = 3.109; E = 0.889; D = 0.058), Station II (H’ = 3.13; E = 0.93; D = 0.054), and Station III (H’ = 3.14; E = 0.914; D = 0.055). The similarity index between stations was <50%. Based on the saprobic index, Station I (1.96) indicated very light pollution, Station II (0.63) indicated light pollution, and Station III (0.33) indicated moderate pollution.