USING STYGOFAUNA AS BIOLOGICAL TRACERS TO DETERMINE HYDROGEOLOGICAL PARAMETERS IN DEFORMED KARST TERRANES

Geology plays a significant role in both the storage and transport of groundwater, as well as the distribution and diversification of subterranean and aquatic organisms. The effect that stratigraphic and structural features might have on hydrogeology is by acting as either conduits or barriers to groundwater flow. Determining whether hydrologic connections exist between two terranes can be difficult, especially when time and hydraulic gradients might not be sufficient for the injection of chemical tracers or pumping tests might not be practical. By using endemic stygofauna as biological tracers, hydrogeological parameters may be deduced by comparing genotypic and phenotypic relationships between populations on either side of potential groundwater barriers due to allopatric isolation. If geologic barriers are effective in preventing the exchange of groundwater between strata or structures, they might also be effective in retaining populations of stygofauna and preventing the exchange of genetic material. On the contrary, if geologic barriers are not in place, or effective, the exchange of groundwater might also permit the migration of stygofauna between terranes and allow for the exchange of genetic material. In karst, these effects are most significant as the diameter of pores increases above 10 mm. Using stygofauna to confirm connections of this size would be appropriate since most juvenile stygofauna are capable of navigating fracture apertures with diameters of about 1 mm. Looking at examples from the Arbuckle Mountains of southern Oklahoma, we examine genotypic and phenotypic relationships of endemic stygofauna, using DNA barcoding and taxonomic methods. By employing these techniques, we can assess the effectiveness of various types of stratigraphic and structural features as either pathways or as barriers in a region heavily altered by structural deformation and modified by karst processes.