COUPLING POPULATION GENETICS AND TRACER HYDROLOGY TO CHARACTERIZE FLOW-PATH DYNAMICS IN A KARST SYSTEM
To address this lack of temporal information, we combined the more traditional techniques with population genetic data to determine if these data can provide insight into seasonal or longer changes in connections between conduits. Dye traces from Fern Cave, a 15-mile-long, multilevel cave system in Nat Mountain, Alabama, identified two isolated flow paths within the cave that drain separate parts of the mountain. Major ion geochemistry showed a Ca/Mg-CO3 water type, suggesting primary storage in the limestone rather than in overlying sandstone, and water isotope data suggest rapid recharge, with minimal evaporation. Hydrograph data show the system to be extremely flashy, with the lower section of the cave inundated by periodic floods of the nearby Paint Rock River. Population genetics data suggest that these two separate flow paths are connected during these floods because the downstream populations of both systems are similar. Although upstream populations show some similarities in genetics, hydrologic barriers, in the form of large waterfalls, likely separate populations within the same stream.