Species diversity of Odonata as a bioindicator of water pollution in the Batang Harau watershed, Tanah Datar District, West Sumatra

Abstract The Batang Harau River was located in Nagari Paninjauan, X Koto District, Tanah Datar Regency, West Sumatra. The local community uses this river as a water source to carry out various daily activities, such as the irrigation of rice fields; household activities, and household waste disposal. The research aimed to analyze the comparison of dragonfly species diversity as a bioindicator for pollution in several habitat types (natural, rice fields, and settlements). The observations were made by exploring and walking along the river in the morning (9 am – 12 am) and evening (3 pm - 5 pm). The Visual Encounter Survey (VES) method was modified using a 20 m x 10 m plot, and all dragonflies found in this area were collected using an insect net. The data obtained were analyzed using the ShannonWienner diversity index, the Margalef species richness index, and Simpson’s dominance index. A total of 280 individuals, 12 species from 7 families, were collected in this study site. Most Odonata species were found in natural areas, followed by rice fields and settlements. The environmental conditions have affected the diversity of Odonata. The odonates can be used as bioindicators of the aquatic environment, especially in the suborder Zygoptera, which is dominantly found in natural habitats.