Water Resources Research Act Program

Details for Project ID 2011IL219B

Influence of Algal/ Bacterial Interactions on Denitrification in Stream Biofilms

Institute: Illinois
Year Established: 2011 Start Date: 2011-03-01 End Date: 2012-02-29
Total Federal Funds: $22,672 Total Non-Federal Funds: $46,760

Principal Investigators: John Kelly, Kimberly Gray, Christopher Peterson, Miguel Rojas

Abstract: Over the last century the input of nitrogen to the environment, largely in the form of nitrogen fertilizers used in agriculture, has increased dramatically, and the resultant increases in nitrogen levels in surface waters have lead to decreases in water quality. Nitrogen pollution of rivers and streams is an especially significant issue for the Midwestern United States and for the State of Illinois due to the high levels of agriculture in this region. Due to the significant environmental problems linked to N pollution, there is interest in biological processes that can remove nitrogen from aquatic ecosystems. Denitrification is a microbially catalyzed process through which biologically available nitrogen can be removed from aquatic systems as nitrogen gas. High rates of denitrification are often observed in aquatic sediments, but recent studies have demonstrated that periphytic biofilms (composed of algae and bacteria) can be hotspots for denitrification activity within aquatic ecosystems. Biofilms therefore have the potential to make significant contributions to nitrogen removal from aquatic ecosystems. Unfortunately relatively little is known about the mechanisms driving denitrification in these biofilms. The goal of our project is to explore the ecology of periphytic biofilms with a specific focus on denitrification and to test our hypothesis that within periphytic biofilms, algal species identity will influence both the species composition and activity of denitrifying bacteria. To accomplish this goal we have conducted field work in streams and rivers in Northern Illinois, and we are proposing herein to use leading-edge molecular biology tools (quantitative real-time PCR and high throughput tag pyrosequencing) to profile denitrifying bacterial communities within periphytic biofilms collected from these habitats. We are also proposing to initiate a new set of field experiments focused on streams adjacent to agricultural sites. This project will improve our understanding of the ecology of denitrification in streams and rivers, and it will provide insight into environmental factors that influence denitrification rates. This work could have significant implications for the management and remediation of nitrogen pollution and the design of systems for nitrogen removal, including wetland restoration and the construction of artificial treatment wetlands. Specifically, this project will provide details on environmental and ecological conditions that will maximize denitrification, details that could be incorporated into the design of treatment systems in order to maximize nitrogen removal.