The Philip M. Smith Graduate Research Grant for Cave and Karst Research

2019 Grants

Sarah Burgess ($2,325)
M.S. Student
Department of Earth and Atmospheric Sciences
Indiana University

Carbon Cycling in the Karst Aquifers of South-Central Indiana

Abstract: The classic karst landscape of the Mitchell Plateau in southern Indiana is shaped by the dissolution of limestone by carbonate equilibrium reactions with water, resulting in a complex epikarst and subsurface drainage where meteoric, surface, and groundwaters all interact. These chemical reactions produce dissolved inorganic carbon (DIC) derived principally from the atmosphere and from bedrock. DIC in karst groundwater is a sink for atmospheric carbon and the rate of carbon flux is dependent on hydrology, geochemistry, climate, and land use. The juxtaposition of farmland on the thin soils and epikarst of the Mitchell Plateau may contribute to excess carbon in groundwater via soil erosion and animal waste, which stable isotopes may be able to source and track. As part of a larger research program into karst aquifer geochemistry and carbon systematics in the critical zone, this study will quantify DIC in water samples from sinking streams, caves, and springs across two karst basins. Each study site represents an inflow, throughflow, or outflow of the karst aquifer with unique hydrologic and geochemical characteristics. In this proposal, I will use stable isotopes of oxygen, hydrogen, and carbon (δ18O, δ2H, and δ13CDIC) as tracers for the sources of mixed waters and inorganic carbon in the Mitchell Plateau to better quantify the role of karst in the global carbon cycle and the impact of land use on carbon flux in karst.


Anna Harris ($2,800)
M.S. Student
Department of Geography and Geology
Western Kentucky University

Quantifying the Impacts of Timber Harvest on Karst Systems in the Tongass National Forest, Alaska

Abstract: The Tongass National Forest in southeast Alaska is home to a dynamic and vulnerable karst ecosystem. Karst in the Tongass is distinct, supporting significant micro and macro regional ecosystems: well-developed old growth forest, prodigious salmon streams, and muskeg peat. This fragile ecosystem sits at the nexus of timber harvest, climate change, and US Forest Service land management practices. While human impacts on karst terrains are well-studied, few studies have been conducted regarding the implications of deforestation on karst, specifically on heavily managed landscapes in a temperate rainforest. This study will compare and contrast the relationship between forest regrowth, evapotranspiration, natural flow regimes, and water quality in two karst watersheds: an old growth forest that has never been logged and a previously logged second growth forest. Climate data will be recorded at 10 minute intervals, in order to calculate evapotranspiration. High-resolution data will be collected for pH, temperature, specific conductivity (SpC), and turbidity at 10-minute intervals at the major springs in each watershed. Grab samples for cations (Ca, Mg) and alkalinity (HCO3) will be collected in order to statistically develop a relationship with SpC and calculate dissolution rates within each watershed at high-resolution. These data are expected to show how timber harvest has affected the nature of these karst systems. Given the societal and scientific value of the study area, the scarcity of karst research in the Pacific Northwest, and the co-sponsorship of the US Forest Service, this study is a valuable contribution to a growing body of data with relevant practical applications.


Morgan O. Smith ($2,975)
M.S. Student
Department of Biology
Appalachian State University

Manganese (II) Oxidizing Microbes and Mineral Induced Selection

Abstract: Manganese oxidizing microorganisms are abundant in nature and play an important role in biogeochemical cycles in the environment. Cave and karst systems are important natural resources because they provide significant sources of the world’s drinking water and support unique biological communities. The microbial ecology of Mn oxide deposits is not well understood, and even less is known about the factors that stimulate Mn-oxidizing microbes in situ. Previous studies suggest that biological Mn oxide minerals are strongly oxidative and have highly charged surfaces making them highly reactive. For example, they have the ability to degrade humic substances, scavenge reactive oxygen species, concentrate rare earth elements, and influence trace metal bioavailability and speciation. However, the microbes that generate these reactive Mn oxides show a strong preference for some rock/mineral surfaces over others, even when these surfaces are in direct proximity to each other. Based on field observations in a variety of cave, karst, and wetland environments, it is predicted that Mn oxidizers prefer to grow on quartz rather than calcite. The aim of this study is to identify which Mn oxidizing microbes within a local microbial community preferentially colonize some minerals instead of others. Predicting how and where Mn oxides will grow is a vitally important tool for the production of reactive mineral species, which can be used in a variety of water filtration and bioremediation technologies.


Pamela Beth Hart ($2,000)
Ph.D. Student
Department of Biological Sciences
Louisiana State University

Population Genomics of a Cavefish Species Complex: Implications for Conservation and Aquifer Connectivity

Abstract: Cave-obligate aquatic organisms are particularly difficult to monitor for conservation needs due to cryptic diversity and unknown cave and water source connectivity. The promise of Next Generation genomic sequencing could offer an unprecedented ability to accurately determine the diversity and relatedness of aquatic cave-obligate organisms (e.g., cavefishes). The Southern Cavefish (Typhlichthys subterraneus) is the largest ranging cavefish found worldwide and represents a species complex (i.e., encompassing multiple species) of which multiple lineages are reported as Vulnerable, Critically Imperiled, or Imperiled. However, the extent of introgression, hybridization, and connectivity of these lineages has not been thoroughly investigated. Thus, the Southern Cavefish is a great subject to test the application of Next Generation sequencing to cave-obligate species complexes, in particular those with lineages of conservation concern. I will use population genomic analyses on a dataset of Single Nucleotide Polymorphisms (SNPs) harvested from Ultraconserved Element (UCE) loci to determine diversity and phylogeography of the Southern Cavefish species complex. By using this contemporary technique to assess relationships, status, and population sizes of Southern Cavefish lineages, we can help protect these North American endemic cavefishes, determine the applicability of this technique to other aquatic cave-obligate species complexes, and increase our understanding of aquifer and cave connectivity.

Page last updated or validated on January 16, 2020