Microbes regulate many important ecological processes such as nitrogen cycling in wetland ecosystems. A major area of uncertainty is whether the composition of the microbial community is an important determinant of the rates at which nitrogen is processed, or if these rates are independent of which microbial taxa happen to present. This doctoral dissertation improvement research project will address this knowledge gap while simultaneously examining potential climate change impacts on nitrogen biogeochemistry. Specifically, the intrusion of saltwater into historically freshwater wetlands, an anticipated consequence of sea level rise, is expected to alter microbially-mediated nitrogen cycling processes including denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA). A reciprocal transplant experiment that moves soil microbial communities between saltwater and freshwater wetlands will be used to determine the importance of environmental conditions, especially salinity, on DNF and DNRA activity rates. Further, by using soil cores that are both open and closed to migration from the host environment this work will explicitly test what role community composition plays in determining these biogeochemical rates.
Developing an understanding of the relationship between microbial community composition and rates of ecosystem processes is important for understanding the impacts of climate change, land use change, and other factors influencing ecosystems worldwide. The findings will also be useful in enhancing environmental engineering efforts to mitigate nitrogen pollution. Undergraduates from Virginia Commonwealth University's exceptionally diverse student body will be involved in all aspects of this research, and results will be brought directly into an existing course in Applied and Environmental Microbiology.
