Diversity and Distribution of Phytoplankton in the Singkil Peat Swamp Water, Aceh Province, Indonesia

Abstract

The Singkil peat swamp (SPS) is threatened by land conversion into oil palm plantations and settlements, thus posing a significant threat to aquatic biodiversity, including phytoplankton as a primary producer in the aquatic food chain, and yhytoplankton is commonly used as one of the bioindicators for monitoring aquatic health. Therefore, this research aimed to analyze the diversity and distribution of phytoplankton in Singkil peat swamp water as a basic data for monitoring aquatic condition of SPS in the future. The analysis was conducted at 11 sampling locations, which were determined purposively. Phytoplankton samples were collected using plankton net no. 25 by filtering 100 liters of surface water to a depth of 30 cm, while water samples were obtained between 10.00 AM to 15.00 PM. The filtered samples were put into a bottle and added with six drops of 4% Lugol solution. The results showed that there were 32 species of phytoplankton belonging to 8 classes, namely Bacillariophyceae, Cyanophyceae, Chlorophyceae, Cryptophyceae, Euglenoidea, Trebouxiophyceae, Ulvophyceae, and Zygnematophyceae. The highest abundance of phytoplankton was found in Seunabok Pusaka with a density of 2,480 cells/L, and Cyclotella sp. was identified as the most frequently occurring species. The average diversity index obtained was 1.50, falling into the medium category, while the average dominance index of 0.32 in the low category showed no dominant species. Furthermore, the average phytoplankton species richness index was in the low category. The Seuneubok and Impadang had a high similarity in community structure compared to other locations. The majority of phytoplankton showed a uniform distribution pattern, although three species had a group distribution pattern. A total of six bioindicator species were found namely Nitzchia, Oscillatoria, Euglena, Leptocylindrus, Phacus, and Chlorella. Seunabok Pusaka AFD 4 (St. 2) showed a higher number of bioindicator species, indicating that the location had been polluted.