<![CDATA[Bandar Khayangan Lake in Pekanbaru City is utilized for various activities, including tourism, aquaculture, irrigation, and domestic purposes. The increasing intensity of human activities around the lake has the potential to degrade water quality through the input of domestic waste, residual fish feed, and tourism-related litter. These conditions may affect the presence of plankton, which play an important role as bioindicators of water quality. This study aimed to analyze the plankton diversity in Bandar Khayangan Lake and assess the condition of the aquatic environment based on the structure of the plankton community. A quantitative descriptive method was employed, with samples collected from three observation stations. The observed parameters included plankton species composition and diversity indices (phytoplankton and zooplankton), as well as physicochemical parameters such as temperature, pH, water transparency, and dissolved oxygen (DO). Data were analyzed using the Shannon–Wiener diversity index. The results revealed that the phytoplankton community consisted of 14 species belonging to 4 classes, namely Bacillariophyceae, Chlorophyceae, Cyanophyceae, and Dinophyceae, with Chlorophyceae being the dominant class (53.55%). The zooplankton community consisted of 3 species from 2 classes, namely Branchiopoda and Monogonota, with Branchiopoda as the dominant class (84.62%). The phytoplankton diversity index ranged from 2.49 to 2.58, indicating a moderate diversity level, while the zooplankton diversity index ranged from 0.69 to 1.05, indicating low to moderate diversity. Water quality parameters showed temperatures ranging from 29.3–30.0°C, transparency from 54–79 cm, pH from 5.20–6.80, and dissolved oxygen from 5.92–6.52 mg/L. These findings indicate that the waters of Bandar Khayangan Lake are still capable of supporting plankton communities, although signs of environmental pressure from human activities were observed at several sampling locations.]]>
