Okta Fina Arianti

Urbanization and habitat fragmentation threaten biodiversity and contribute to ecological imbalance, particularly in freshwater ecosystems. Dragonflies (Odonata), which are highly sensitive to environmental changes, serve as reliable indicators of aquatic ecosystem health. However, research on Odonata diversity in urban rivers remains limited, including in Surabaya. This study aims to determine dragonfly species diversity and identify habitat-related factors influencing their distribution along the Segara Kenjeran River. A quantitative ecological survey was conducted at three observation stations with differing habitat characteristics. Data were collected using the Visual Encounter Survey technique, enabling direct identification and counting of individuals in the field. Sampling took place from October to November 2022 under similar weather conditions to reduce environmental variability. The three stations were selected based on variations in vegetation structure, shading, canopy cover, and riverbank conditions. Station 3 exhibited the highest species diversity and abundance, while Station 1 had the lowest. Dominant species across all stations included Orthetrum sabina and Pantala flavescens, both known for broad ecological tolerance. Environmental measurements showed that dissolved oxygen (DO) levels were highest at Station 3, whereas biochemical oxygen demand (BOD) was lowest, indicating better water quality. These results align with dragonfly preference for well-oxygenated habitats. Shannon Wiener diversity indices confirmed the observed patterns, highlighting more stable ecological conditions at Station 3. Overall, the Segara Kenjeran River supports moderate Odonata diversity, shaped by environmental factors such as DO levels, vegetation, and water flow. Continued monitoring is recommended to track ecological changes in this urban river system.