Abstrak
The success of tiger shrimp (Penaeus mondon) aquaculture in ponds is highly influenced by water quality, the presence of pests and diseases, the fertility of the aquatic environment, and the availability of natural feed such as plankton. This study aims to analyze the plankton community structure in traditional tiger shrimp ponds on Tibi Island, Bulungan Regency. The research was conducted from May to September 2024. Plankton samples were collected eight times (every two weeks) using a composite sampling technique. The study focused on species identification, abundance, and ecological indices including diversity index, evenness index, and dominance index. Results showed that phytoplankton were dominated by the - classes Bacillariophyceae and Zygnemophyceae, while zooplankton were predominantly from the class Maxillopoda. Phytoplankton abundance ranged from 131-299 cells/L in plot 1 and 177-345 cells/L in plot 2, indicating oligotrophic conditions. The phytoplankton diversity index ranged from 0.88-1.51 (plot 1) and 0.43-1.29 (plot 2), reflecting low to moderate diversity levels. Evenness index ranged from 0.40-0.69 (plot 1) and 0.18-0.55 (plot 2); dominance index ranged from 0.24-0.50 (plot 1) and 0.25-0.78 (plot 2). Zooplankton abundance was recorded at 0-56 ind/L in plot 1 and 0-47 ind/L in plot 2 (also indicating oligotrophic conditions). Zooplankton diversity index ranged from 0.00-1.33; evenness index from 0.00-1.00; and dominance index from 0.00-1.00. The overall plankton community structure suggests that the aquatic environment remains relatively fertile and continues to support traditional tiger shrimp aquaculture.