Diatom Community Structure in 305–395 cm Depth of Balekambang Lake as Bioindicator of Water Quality

Natural water areas on the Dieng Plateau continue to shrink due to eutrophication. Balekambang Lake is one of the seven remaining lakes on the Dieng Plateau, so it is necessary to take an ecological approach in the form of monitoring to maintain its sustainability. One method of monitoring is by using diatoms. Diatoms are microorganisms from the Bacillariophyta group commonly used as water indicators because they can be well preserved in the sediment layer. This study aimed to conduct so that the abundance and diversity of diatom species can be known as an indicator of water quality. The method used was to take samples at the bottom of the water using piston coring. Sediment samples were then separated by 10 cm for observation at each depth. Samples were digested, washed, and precipitated using 10% HCl, 10% H2O2, and distilled water to obtain a sediment of diatom residues. Diatoms were observed under a 1000x magnification binocular microscope with the help of immersion oil. Based on the observations, 68 species, 33 genera, from 17 families were found. Epithemia alpestris, genus Cyclotella, and Fragillariatenera are commonly seen species and show characteristics of waters with fluctuating acidity and eutrophic. Observations of diversity, dominance, and evenness indices show a stable community structure. Still, it should be noted that species such as Epithemia alpestrisand the Cyclotella genus generally show polluted waters due to agricultural activities that are not based on conservation principles.