Odonata community structure and patterns of land use in the Atewa Range Forest Reserve, Eastern Region (Ghana)

Recent studies have indicated that frequent anthropogenic disturbances in tropical developing countries are primary drivers of reduction in community diversity and local extinction of many arthropods, including dragonflies. We assessed the impact of anthropogenic disturbances on odonate assemblages across three different land use types, in a biodiverse nature reserve in Ghana. A total of 37 transects (100 x 10 m) were used to survey odonate species over two seasons and three rivers which pass through agricultural, matured forest and forest margin habitats. A total of 6940 individuals, belonging to 53 species (23 Zygoptera and 30 Anisoptera) in eight families, were recorded. Sapho ciliata (15% relative abundance) was the most abundant zygopteran, whereas Orthetrum julia (4.8% Relative abundance) was the dominant anisopteran. Rarer species like Umma cincta, Chlorocnemis sp. and Elattoneura sp. were represented by < 50 individuals. The effective number of species was affected by the surrounding terrestrial habitat type and this most strongly reflected the difference between agricultural habitats (8.09 ± s.e. 0.41) and matured forests (5.0 ± s.e. 0.24). A canonical correspondence analysis revealed that turbidity, surface water temperature, canopy cover and channel width were the key factors that influenced odonate assemblages. Degraded habitats were dominated by generalist and heliophilic dragonflies, while matured forest habitat included more stenotopic damselflies and dragonflies. These findings improve our understanding of the drivers of odonata distributions and diversity and will help river managers use odonates to monitor riverine health, as part of conservation activities.