33. A survey of aquatic macro- and micro-invertebrates of vernal granite outcrop pools in North Georgia

Abstract

Vernal granite outcrop pools are small, non-persistent bodies of freshwater that form in granite depression and are known to provide habitat for a plethora of endemic and endangered plant species. These pools offer refugia and habitat for a richness of animal species, many of which display traits for survival in these extreme and ephemeral ecosystems. While the pools are rich with life, there is no scientific literature about what macro- and micro-invertebrates inhabit them in North America, and only one study out of Australia published surveys on granite pools. Based on the study from Australia, each outcrop has the potential to host one to several undiscovered species. The state of Georgia hosts a majority of the granite outcrops of North America with estimates of up to 90% of the outcrops lying within its borders. Choosing outcrops in Georgia as study sites give us a good idea of the total diversity of North American pools. If these pools are acting as refugia for endemic or endangered species, then our work is imperative in helping to understand and protect these vulnerable habitats and organisms. Sampling was done four times throughout early spring until mid-summer at 4 locations, with the potential of adding more, all located in North Georgia: Stone Mountain, Arabia Mountain, Panola Mountain, and Thompson Mill Forest Arboretum. Most of the specimens collected were rotifers, chironomids, and culicids. Of the locales, Thompson Mill and Arabia Mountain had the most abundance while Arabia Mountain and Panola Mountain had the highest species diversity. We have identified all organisms to family, and we are currently in the process of identifying them to species. We have noted two rotifers (Notholca sp. & Lepadella sp.) that are promising candidates for new species and warrant closer inspection.