Date of Award
Master of Science (MS)
Wildlife and Fisheries Biology
Positive interactions such as facilitative habitat modification are often strong drivers in structuring communities. The Bluehead Chub (Nocomis leptocephalus) is a common fish in Piedmont streams of the southeastern USA that builds gravel mound spawning nests that other native fish species utilize as critical spawning substrate. These nests are colonized by other freshwater benthic organisms, though few studies have investigated these colonizing assemblages. The goal of this study was to quantify differences in benthic assemblage composition and abundance between Bluehead Chub nests and unmodified streambed substrate as well as relative taxa microhabitat associations in relation to stream reach-wide benthic assemblages as a first step in determining the importance of Bluehead Chub as ecosystem engineers to non-fish communities. To address this, we surveyed 10 streams in northwestern South Carolina and collected 28 Bluehead Chub nests and unmodified paired substrate samples and 12 reach-wide assemblage samples. Total benthic assemblage counts, richness, and Shannon diversity index values were calculated for each sample, and we conducted two partial CCAs to investigate taxonomic community composition between nests and paired substrate, and between nests, paired substrate, and the reach. We collected and identified 7746 individual organisms in total, representing 64 families and 78 genera, of which 50 families and 67 genera were found in Bluehead Chub nests. Assemblages in Bluehead Chub nests were significantly more abundant and diverse than paired substrate, but both nests and paired substrate were significantly less diverse than the overall reach. Taxonomic assemblage composition significantly differed between nests and paired substrate, and nest and paired substrate were significantly different from the overall reach. Benthic assemblages in Bluehead Chub nests may follow individual taxa utilization of nests for structure or food availability; taxa more closely associated with chub nests often have traits or behaviors that may allow them to better exploit Bluehead Chub nests than taxa that are not as closely associated with the nests. These benthic assemblages in Bluehead Chub nests and paired substrate appeared to be similar subsets of the more diverse reach. It is likely that Bluehead Chub nests serve as a lithophilic “improvement” of the mesohabitat and aggregates benthic organisms from its surroundings rather than hosting a unique assemblage; we do not expect any ecologically significant impacts of Bluehead Chub nests on non-fish benthic communities beyond the microhabitat scale.
Evelyn, Isabel, "It’s Free Real Estate: Benthic Assemblage Composition on Bluehead Chub Nests in Southeastern Streams" (2023). All Theses. 3970.
Available for download on Friday, May 31, 2024