Dr. Emma J. Rosi-Marshall
Aquatic Ecologist
Ph.D., 2002, University of Georgia

Dr. Rosi-Marshall conducts research on factors that control and influence ecosystem function in human-dominated ecosystems. Freshwater is one of our most vital and threatened resources; understanding how human-driven global change impacts freshwater ecosystem function is essential. Dr. Rosi-Marshall's research focuses on several aspects of human modifications to freshwater ecosystems such as land use change and restoration, widespread agriculture and associated crop byproducts, urbanization and the release of novel contaminants, and hydrologic modifications associated with dams.

Current Research

Globally, direct modification of rivers for hydropower generation is one of the most dramatic effects humans have had on large river ecosystems.
In most cases, hydropower dams are constructed on large rivers which pose methodological challenges for stream ecosystem ecologists. In collaboration with Drs. Robert Hall, University of Wyoming, Colden Baxter, Idaho State University, and Ted Kennedy, Grand Canyon Monitoring and Research Center USGS (research funded by USGS), we are using quantitative food web approaches to examine the energetics and potential food limitation of the endangered humpback chub in the Grand Canyon reach of the Colorado River below Glen Canyon Dam. We are employing a large number of tools to reconstruct an extensive carbon budget and energetic food web of the river. These data will inform management of this highly altered but treasured ecosystem.

Our understanding of nutrient cycling in large river ecosystems is currently limited.
In order to address these limitations, Drs. Jennifer Tank, University of Notre Dame, Michelle Baker, Utah State University, and Robert Hall, University of Wyoming, and I developed a new method to measure nutrient uptake in a large river (Tank et al. 2008). These data are some of the first empirical measurements of nutrient uptake in a river and we are extending this research to include measurement of nutrient uptake in other large river ecosystems throughout the Western and Midwestern US.

Crop selection may have consequences for stream ecosystem function.
In collaboration with Dr. Jennifer Tank, University of Notre Dame, Dr. Todd Royer, Indiana University and Dr. Matt Whiles, Southern Illinois University, I am examining the cycling of novel allochthonous carbon, i.e. agricultural crop by-products, in Midwestern agricultural streams. Corn production dominates much of the Midwestern US landscape. We are investigating the influence of corn varieties on stream ecosystems. Our work demonstrates that corn byproducts enter streams and are retained within headwater reaches. In laboratory feeding trials, when caddisflies were fed on genetically-modified corn material, they had decreased growth rates (Rosi-Marshall et al. 2007).

The widespread use of novel contaminants, such as pharmaceuticals, have unknown consequences for stream ecosystems.
Currently, I am conducting research on a novel class of contaminants associated with urban areas known as pharmaceuticals and personal care products (PPCPs). PPCPs include drugs, antibiotics, antimicrobials found in detergents, perfumes, etc. I am currently investigating whether concentrations of PPCPs found in surface waters affect ecosystem function (funding provided by Illinois Water Resources Association). The methods we are developing allow us to explore how chemical stressors influence ecosystem function, a difficult task in urban streams with multiple stressors. In collaboration with Dr. John Kelly (Loyola University Chicago), I have started measuring the effects anti-microbials on the composition and functioning of stream biofilms.

The effects of restoration on stream ecosystem function are not well understood.
In collaboration with Drs. Jennifer Tank and Gary Lamberti, at the University of Notre Dame, I conducted an experimental addition of large woody debris (stream restoration) to examine its effects on ecosystem function in three streams of the Upper Peninsula of Michigan. This research has shed light on the influence of wood on ecosystem function and contributed to our measurements of nutrient uptake, secondary production and wood levels in streams of the Upper Midwest.

Selected Publications

• Entrekin, S.A., J.L. Tank, E.J. Rosi-Marshall, T.J. Hoellein, G.A. Lamberti. Response of secondary production by macroinvertebrates to large wood addition in three Michigan streams. In Press. Freshwater Biology.
• Hoellein T. J., Tank, J.L., E.J. Rosi-Marshall, S.A. Entrekin. 2009. Temporal variation of substratum-specific rates of N uptake and metabolism and their relative contribution at the stream-reach scale. Journal of the North American Benthological Society 28: 305-318.
• Griffiths, N.A., J.L. Tank, T.V. Royer, C.P. Chambers, M.A. Evans-White, T.C. Frauendorf, E.J. Rosi-Marshall, M.R. Whiles. 2009. Microbial respiration and decomposition of conventional and genetically-engineered corn detritus in Midwestern US agricultural streams. Ecological Applications 19: 133-142.
• Tank, J. L., E. J. Rosi-Marshall, M.A. Baker R. O. Hall. 2008. Are rivers just big streams? Using a novel method to quantify nitrogen demand in a large river. Ecology 89: 2935-2945.
• Entrekin, S.A., J. L. Tank, E. J. Rosi-Marshall, T. J. Hoellein, and G. A. Lamberti. 2008. Responses in organic matter accumulation and processing to an experimental wood addition in three headwater streams. Freshwater Biology 53: 1642-1657.
• Marvier, M., Y. Carriere, N. Ellstrand, P. Gepts, P. Kareiva, E.J. Rosi-Marshall, B. Tabashnik, L. L.Wolfenbarger. 2008. Harvesting data from USA's grand experiment with genetically engineered crops. Science 320: 452-453.
• Rosi-Marshall, E. J., J. L. Tank, T.V. Royer, M.R. Whiles, M. Evans-White, C. Chambers, N.A. Griffiths, J. Pokelsek, and M.L. Stephen. 2007. Toxins in transgenic crop byproducts may affect headwater stream ecosystems. Proceedings of the National Academy of Sciences 104:16204-16208.
• Entrekin, S.A., E.J. Rosi-Marshall, J.L. Tank, T.J. Hoellein, G.A. Lamberti. 2007. Macroinvertebrate secondary production in forested sand-bottom streams of the upper Midwest. Journal of the North American Benthological Society 26: 472-490.
• Hoellein, T. J., J. L. Tank, E. J. Rosi-Marshall, S. A. Entrekin, and G. A. Lamberti. 2007. Controls on spatial and temporal variation of nutrient uptake in three Michigan headwater streams. Limnology and Oceanography 52: 1964-1977.
• Cordova, J., E.J. Rosi-Marshall, A. Yamamuro, G.A. Lamberti. 2007. Quantity, controls, and functions of large woody debris in Midwestern U.S.A. streams. River Research and Applications 23: 21-33.
• Rosi-Marshall, E.J., A.H. Moerke, and G.A. Lamberti. 2006. Ecological responses to rehabilitation of a Northern Michigan trout stream. Environmental Management 38: 99-107.
• Rosi-Marshall, E.J. and J.L. Meyer. 2004. Quality of suspended fine particulate matter in the Little Tennessee River. Hydrobiologia 519: 29-37.
• Rosi-Marshall, E.J. 2004. Quality of suspended fine particulate matter along an urban river. Freshwater Biology 49: 515-625.
• Rosi-Marshall, E.J. and J.B. Wallace. 2002. Invertebrate food webs along a stream resource gradient. Freshwater Biology 47:129-141.