Species composition and individual abundance of plankton in acid sulfate soil brackishwater ponds in Kotabaru Regency, South Kalimantan Province

This study aims to determine the composition of species and individuals abundance of plankton in acid sulfate soil brackishwater ponds in Kotabaru Regency, South Kalimantan Province. The plankton was collected and preserved with 1% Lugol solution and species was identified by microscope and calculated with cell counting methods. Water quality variables measured in situ; temperature, transparency, salinity, DO, and pH, which existed; total organic matter, NO 2 -N, NO 3 -N, NH 3 -N, PO 4 -P and total suspended solids. The results showed that in acid sulfate soil ponds, were found 8 species of phytoplankton, classified into 4 classes i.e., Bacillariophyceae (4 species), Cyanophyceae (1 species) Dinophyceae (2 species) and Chlorophyceae (1 species) with an abundance of 10-410 ind./L while zooplankton type were found 9 species classified into 2 classes, i.e. Crustaceae (8 species) and Rotatoria (1 species) with an abundance of 14-637 ind./L. The dominant species of phytoplankton is Nitzschia sp from the Bacillariophyceae class with abundance are 482 ind./L, while the zooplankton type dominated by Copepoda sp from the Crustaceae class with an abundance of 583 ind./L. Value of dissolved oxygen, pH, NO 3 -N and total suspended solids in the pond are increased parallel with the increasing abundance of Nitzschia sp; otherwise, abundance Nitzschia sp decreased with increasing NH 3 -N. An abundance of Copepoda sp increased in line with increasing value of dissolved oxygen and pH while decreased with high temperature and NH 3 -N value.