Effect of the Urban Heat Island in Plovdiv City (Bulgaria) on the Species Composition and Distribution of the Dragonflies (Insectа: Odonata)

The current paper researches the impact of the urban heat island effect on the species composition and distribution of dragonflies (Insecta: Odonata) along the Maritsa River in the city of Plovdiv, Bulgaria. The study was conducted on imaginal and larval forms of the species, and the studied area was divided into 3 sub-areas (urban, suburban and rural) according to the proximity to the city center. Along the urban gradient from the rural to the urban zone, an increase in air, water and soil temperature by ≈1-2ºС was observed. Differences were foundalso in the dissolved oxygen in the water, which had the highest values in the rural area (10.70 mg/l) and decreased towards the urban area, where it was 9.03 mg/l. Four dragonfly species were confirmed for the study area, and 2 new species were recorded. The most species were found in the urban zone, probably due to the higher temperatures compared to the other two areas, while at the same time, no larvae were found there, due to the lower amount of dissolved oxygen in the water. The current paper gives a better understanding of the impact that the urban heat island effect has on dragonflies in cities and aims to contribute for timely measures and decisions for the management of wetlands around urban areas.