Date of Award

Spring 5-7-2022

Degree Type


Degree Name

Master of Science - Forestry



First Advisor

Yanli Zhang

Second Advisor

Christopher M. Schalk

Third Advisor

Daniel Saenz

Fourth Advisor

Carmen MontaƱa


Land use practices and physical alterations of ecosystems result in habitat loss and fragmentation, while chemical alterations, such as pollutant input, reduce habitat quality and health of exposed organisms. Here, I investigated the effects of watershed- and local-scale environmental variables on the occupancy, abundance, and mercury accumulation of a threatened aquatic species (Macrochelys temminckii, i.e., alligator snapping turtle) within the southwestern periphery of its distribution. Hierarchical modeling suggested the distribution of the species is more affected by watershed-scale land-cover than local habitat, and provided a baseline estimate of average species abundance across its range in eastern Texas. Abundance and occupancy were predicted by geographic location, and occupancy associated positively with forest cover. Mercury concentrations were predicted by environmental features at multiple scales, whereas body size had little effect. This research corroborates evidence that land use impacts aquatic species, as well as the susceptibility of aquatic systems to mercury accumulation.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Available for download on Wednesday, May 03, 2023



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