Department Chair

I. Martha Skerrett, Chair and Associate Professor of Biology

Date of Award


Access Control

Open Access

Degree Name

Biology, M.A.


Biology Department


Christopher M. Pennuto, Ph.D., Professor of Biology

Department Home page

First Reader

Gary W. Pettibone, Ph.D., Professor of Biology

Second Reader

Randal J. Snyder, Ph.D., Professor of Biology


Microbial communities are ubiquitous and carry out valuable functions in the environment. Decomposition of leaf material by microbial communities is important to return nutrients back to both terrestrial and aquatic organisms. Perturbations to the environment like the arrival of invasive species can have an impact on the structure and functions of the microbial community. The round goby (Neogobius melanostomus) is a Ponto-Caspian fish introduced into the Great Lakes which has since secondarily invaded tributary streams and rivers. Studies have shown they alter invertebrate communities, and these alterations have impacted organic matter decomposition. Stream studies suggest leaf litter decomposes less rapidly in the presence of gobies and I sought to determine whether the reduction in decomposition was a function of changes in microbial community richness. Leaf litter packs were used as a substrate for microbial colonization and analyzed for decomposition rates at sites with and without gobies present. Leaf material decayed significantly less rapidly when gobies were present. The invertebrate communities were significantly different between sites. The goby-absent site had a higher abundance of shredders when compared to the goby-present site. There were not significant differences in microbial carbon source consumption richness or average color well development (AWCD) for carbon guilds between goby-present and goby-absent sites. There were significant seasonal differences in ACWD for microbial carbon guild usage for several guilds. These data suggest that the presence of round gobies does not alter carbon usage of microbial communities in stream leaf litter but that microbial communities can vary with season.