Brooks, Samantha Grace2024-08-102024-08-102024-08-09vt_gsexam:41207https://hdl.handle.net/10919/120905Keystone species are widely distributed across aquatic and terrestrial ecosystems and are fundamental in preserving the structure, diversity, and stability of an ecological community due to its disproportionately large impact on its community relative to its biomass. As biodiversity of ecosystems becomes more threatened with urbanization and habitat destruction, it is imperative to understand a keystone species' role in maintaining ecosystem function. One of the ways to do so is by examining their significance and connection to the ecosystem food web. Within North American freshwater ecosystems is the pebble nest-building minnow, the bluehead chub (Nocomis leptocephalus; "chub"). Chubs provide spawning habitat for not only themselves, but for other minnows, collectively called "nest associates". In this work, I observe the predatory and potential mutualistic interactions between chubs, nest associates, and their predators. In Chapter 1, I observe spawning nests to identify the predators of adult chubs, nest associates, and embryos. I further investigate how nest visibility covariates including minnow activity, minnow abundance, nest size (area), and nest growth affect predator encounter rate to spawning nests. I found a total of 23 diverse taxa to prey on the adult minnows and minnow embryos on chub spawning nests, 14 predators of which had not been reported in literature. One of these predators was the common snapping turtle (Chelydra serpentina; "turtle"). Additionally, I found that activity, abundance, nest size (area), and nest growth had a significant effect on predator encounter rate, attracting predators to seek spawning nests for prey. In Chapter 2, I investigate the effect of ambient temperature on turtle epizoic coverage during the spawning season and provide preliminary evidence of a potential cleaning symbiotic mutualism between the turtle and minnows. I found that epizoic coverage decreases during the duration of a minnow spawning season after an initial increase with early summer warming, and my results also present unique and shared bacterial communities across three sources, the ambient environment, gut contents of minnows, and turtles. The results additionally revealed there to be bacterial communities unique between minnows and turtles that were not identified in the ambient environment. Overall, this study is first to systematically document predators of chub spawning nests and first to provide preliminary evidence of a cleaning symbiotic mutualism between a freshwater turtle and minnow species (or freshwater turtles and fish in general), which, thus far, has not been explored in freshwater ecosystems. This work demonstrates that chub spawning nests are a crucial entity of the freshwater food web structure across Nocomis' distribution range and reveals that chub spawning nests create an interconnection between a diversity of fauna in a freshwater ecosystem.ETDenCreative Commons Attribution 4.0 InternationalBacteriacleaning symbiosisChelydra serpentinaepizoic organismsfood webskeystone speciesNocomis leptocephalus16S rRNA amplicon sequencingThesis