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.
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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.
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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.
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last updated or validated on January 16, 2020