The Grand Staircase-Escalante National Monument contains sedimentary rocks that have recorded the fluid flow history from Jurassic to Cenozoic time. Despite the importance of understanding these processes and dynamics, our knowledge of past fluid flow in many regions is limited.…
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Bigheaded carp (bighead carp and silver carp) are invasive species in the US and have spread throughout most of the Mississippi River Basin. Population abundance upstream of Lock and Dam 19 (LD19) on the Upper Mississippi River has been limited by the high head dam at this locat…
Estuaries are important habitats to many coastal fishes. Some species of fish can use the low salinity and freshwater environments that estuaries provide, though the exact patterns of usage for these habitats for some species is not well understood. Stable isotope and microchemi…
Once abundant in the Arctic, bison (Bison bison) declined almost to extinction in the North but have subsequently been reintroduced into Alaska. The predecessors of these modern bison were the ancient steppe bison (Bison priscus), which were abundant throughout the Northern Hemi…
Understanding the degree of connectivity among populations, forming migratory links and evaluating factors that influence reproductive fitness is fundamental for the successful management of migratory species of conservation concern. In this thesis I focus on a regionally import…
In this dissertation, the origins of Fe-carbonates in the Paleoproterozoic Gunflint Formation of Ontario, Canada are investigated through petrographic and isotopic analysis of carbonate-rich Gunflint samples as well as experiments designed to elucidate the chemical conditions th…
This study focuses on the history of natural and human-induced environmental change as recorded in the sediments of two lakes: Mountain Lake in the Presidio National Park, San Francisco, California and Big Soda Lake, near Fallon, Churchill County, Nevada. The records of these la…
Black carbon (BC) is the highly graphitized byproduct of incomplete combustion that could be a sink for fixed carbon. Little data is currently available for BC concentrations and fluxes to remote marine environments and there are often great discrepancies between model simulatio…
Trade and exchange exerted a powerful force in the historic and protohistoric past of Island Southeast Asian communities. Exchange and interaction are also hypothesized to have played an important role in the spread of new technologies and lifestyles throughout the region during…
Herbivorous mammals in modern tropical ecosystems are characterized by a high degree of specialization, resulting in the systematic division of food resources among them. In order to test whether this also occurred within ancient tropical ecosystems, stable carbon and oxygen iso…
Western Pacific leatherback turtles migrate to geographically distinct foraging regions. Turtles that nest between April and September in Bird's Head nesting beaches in Papua Barat, Indonesia migrate to the South China Sea (SCS), North Pacific Transition Zone (NPTZ), and Northea…
Despite the importance of tropical rivers to the global carbon cycle, the nature of carbon cycling within these watersheds has been dealt with by only a handful of studies. The current work attempts to address this lack of information, using stable isotope and concentration meas…
The late Pliocene and Pleistocene epochs have been characterized by a series of climate cycles generally referred to as ice ages. The ice ages not only involved high latitude climate oscillations as this designation implies, but also variability in low latitude tropical climate.…
Lowland tropical forests are of special concern for they are the most diverse and the most ecologically complex of all terrestrial ecosystems (Myers 1984), and their destruction would significantly reduce global biological diversity (Turner & Corlett 1996). Forests around the gl…
Oxygen minimum zones (OMZs) are areas in which midwater oxygen concentration can be significantly lower than in non OMZ areas at comparable depths. OMZs are of great interest because of the limits oxygen availability places on life. The potential for OMZ expansion with warming o…
My dissertation investigates the sea-level changes, large perturbations in the oceanic carbon cycle, and enrichments and distribution of iridium (Ir) across the Cretaceous/Paleogene (K/Pg) boundary (∼66 Ma). Biostratigraphic, lithofacies, and sequence stratigraphic analyses of t…
The goal of my dissertation has been to test hypotheses for the origins of high-latitud eclimatic warmth and the subsequent global cooling in the middle Miocene, aimed primarily at understanding the oceanographic evolution of the Pacific realm. I attempted to constrain the exten…
Resource limitation drives fitness-related decisions and constrains the ability of organisms to invest in energetically demanding life history stages. Environmental factors (e.g., temperature) play an important role in affecting resource availability and quality which can downst…
Tectonic models of continental orogens seek to reconstruct the deformation processes associated with large-scale continental collision events. Geographically broad field surveys provide two spatial dimensions, and geochronology provides a third temporal dimension. The missing fo…