Assessment of plankton dynamics of Kaptai Lake, Bangladesh: Insights on the largest manmade lake ecosystems in Southeast Asia

<h2>Abstract</h2> Plankton abundance and distribution are widely recognized as reliable indicators of lake ecosystem health. This study focused on Kaptai Lake, the largest man-made lake in Southeast Asia, to examine the dynamics of plankton communities along with their spatial and temporal variations. Water samples were collected from four pre-selected sampling stations, Jolojan Ghaat, Kandemu, Shubholong Jhorna, and Shubholong Bazar, over a period of 12 months. Plankton abundance and distribution were assessed by counting cells under a microscope. Among the identified plankton taxonomic groups, Chlorophyceae (61.1 %) was the most abundant phytoplankton, while Rotifera (63.3 %) dominated the zooplankton community. A total of 15 phytoplankton and eight zooplankton genera were identified across the selected stations. Significant spatial variations in phytoplankton and zooplankton abundance were observed (<i>p < 0.05</i>), with the highest counts recorded at Shubholong Bazar and the lowest at Jolojan Ghat. However, temporal analysis showed that phytoplankton abundance peaked in October (<i>p</i> < 0.05), whereas zooplankton levels remained relatively stable throughout the year with no significant variation (<i>p</i> > 0.05). The findings of this study provide valuable insights into the plankton community dynamics of Kaptai Lake, offering baseline data for sustainable lake management and fish production.