Abstract

 Odonate nymphs are considered bioindicators of lotic ecosystem health due to their sensitivity to factors including hydrology, substrate composition, and water quality. Species in the genus Macromia are regarded as an indicator of lotic ecosystem health, yet species-specific distribution and habitat associations in the Southern Appalachian region have been poorly described. This study aimed to characterize the distribution and resource partitioning of the three co-occurring Macromia nymph species present in the Southern Appalachian region: Macromia alleghaniensis, Macromia illinoiensis, and Macromia margarita. Nineteen sites were selected that represented a variety of lotic habitats, ranging in stream size and environmental conditions. The environmental variables considered included drainage area, maximum elevation, slope, and watershed land coverage. Macromia nymphs were sampled from these sites to identify species-environment and species-species relationships as well as potential niche differentiation. Resource partitioning was evident among the three species, with drainage area being the largest contributing factor to species distribution. M. margarita was associated with low drainage area systems, while M. illinoiensis was associated with high drainage area systems; M. alleghaniensis showed no clear association with drainage area. No co-occurrence was observed between M. illinoiensis and M. margarita, indicating resource partitioning between these two species. These findings improve the understanding of habitat partitioning in Macromia species and enhance their ability to serve as bioindicators and aid in conservation efforts in southern Appalachian lotic ecosystems. 

Keywords

Macromia, Entomology

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