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Robert Stelzer Ph.D.

Professor and Graduate Coordinator
Phone: (920) 424-0845
Office: Halsey 150

Department of Biology
800 Algoma Blvd.
University of Wisconsin Oshkosh
Oshkosh, WI 54901



Education and Training

Postdoctoral Associate,  Institute of Ecosystem Studies, 2000-2001
Ph.D. University of Notre Dame, Ecology, 2000
M.S.  Michigan State University, Zoology, 1992
B.S. Rockhurst College, Biology, 1988


Courses Taught

Global Change Biology/Ecosystem Ecology (Bio 386/586)- spring semester

Field Ecology (Bio 325/525)- fall

Ecosphere in Crisis (Bio 104)- fall and spring

Graduate Seminar (Bio 748)



Dr. Stelzer’s research interests center on the biogeochemistry and food web dynamics of streams and lakes. His research projects, which typically involve multiple collaborators and students, have included short and long-term studies of how nitrogen is processed in streams, studies of reciprocal controls between nutrients and species in the context of ecological stoichiometry, and large-scale experiments to address the factors that regulate stream food webs. Dr. Stelzer’s current research interests are focused on characterizing microplastics in freshwater food webs and predicting Harmful Algal Blooms in lakes.

Undergraduate students and prospective graduate students: Please contact Dr. Stelzer directly at if you are interested in working in Dr. Stelzer’s lab!


Selected Publications from the Stelzer Lab (*student author)

Stelzer, R.S., M. Shupryt, and R.W. Pillsbury. 2022. Experimental discharge reduction impacts fish, but not invertebrates, in a groundwater-dependent trout stream. Hydrobiologia, In Press. DOI: 10.1007/s10750-022-04807-x

Nozzi, N.*, and R.S. Stelzer. 2021. Responses of fish communities to longitudinal thermal gradients in coldwater, lake outflow streams. Environmental Biology of Fishes, 104:1235–1249. DOI:10.1007/s10641-021-01149-w

Stelzer, R.S., T.B. Parr, M. Coulibaly. 2020. A ten-year record of nitrate retention and solute trends in a Wisconsin sand plains stream: temporal variation at multiple scales. Biogeochemistry, 147:125-147.

Stelzer, R.S. and J.T. Scott. 2018. Predicting nitrate retention at the groundwater- surface water interface in sandplain streams.  Journal of Geophysical Research: Biogeosciences, 123:2824–2838. DOI: 10.1029/2018JG004423

Heling, C.L.*, R.S. Stelzer, H.G. Drecktrah, R.P. Koenigs. 2018. Spatial variation of benthic invertebrates at the whole-ecosystem scale in a large eutrophic lake.  Freshwater Science, 37:605-617.

Stelzer, R.S., E.A. Strauss, M. Coulibaly. 2017. Assessing the importance of seepage and springs to nitrate flux in a stream network in the Wisconsin sand plains. Hydrological Processes 31:2016-2028. DOI: 10.1002/hyp.11161.

Louison, M.J.* and R.S. Stelzer.  2016. Use of first-order tributaries by brown trout (Salmo trutta) as nursery habitat in a coldwater stream network. Ecology of Freshwater Fish 25:133-140.

Stelzer, R.S.  2015. Yearlong impact of buried organic carbon on nitrate retention in stream sediments. Journal of Environmental Quality 44: 1711-1719. doi: 10.2134/jeq2015.02.0073

Koenigs, R.P.*, R.M. Bruch, R.S. Stelzer.  2015. Validation of otolith ages for walleye (Sander vitreus) in the Winnebago System. Fisheries Research 167:13-21.

Stelzer, R.S., Scott, J. T., L.A. Bartsch, T.B. Parr*. 2014. Particulate organic matter quality influences nitrate retention and denitrification in stream sediments: evidence from a carbon burial experiment. Biogeochemistry 119:387-402.

Stelzer, R.S. and D.R. Kashian. 2014. The role of conservation partnerships between scientists and nonprofit agencies in freshwater science and management. Freshwater Science 33:670–673.

Stelzer, R.S., and L.A. Bartsch. 2012. Nitrate removal in deep sediments of a nitrogen-rich river network: a test of a conceptual model. Journal of Geophysical Research- Biogeosciences, 117, G02027, doi:10.1029/2012JG001990 (12 pages).

Anderson, T.J.*, R.S. Stelzer, H.G. Drecktrah, and S.L. Eggert. 2012. Secondary production of Chironomidae in a large eutrophic lake: implications for lake sturgeon production. Freshwater Science, 31, 365-378, DOI:10.1899/11-042.1

Stelzer, R.S., L.A. Bartsch, W.B. Richardson, and E.A. Strauss. 2011. The dark side of the hyporheic zone: depth profiles of nitrogen and its processing in stream sediments.  Freshwater Biology, 56, 2021-2033, DOI: 10.1111/j.1365-2427.2011.02632.x

Stelzer, R.S., Drover, D.R.*, Eggert S.L. & Muldoon, M.A. 2011. Nitrate retention in a sand plains stream and the importance of groundwater discharge. Biogeochemistry, 103, 91-107. DOI: 10.1007/s10533-010-9449-y.

Stelzer, R.S. and B.L. Joachim*. 2010. Effects of elevated nitrate concentration on mortality, growth, and egestion rates of Gammarus pseudolimnaeus amphipods. Archives of Environmental Contamination and Toxicology 58: 694-699. DOI  10.1007/s00244-009-9384-x

Shupryt, M.P.* and R.S. Stelzer. 2009. Macrophyte beds contribute disproportionately to benthic invertebrate abundance and biomass in a sand plains stream.  Hydrobiologia 632: 329-339.  DOI 10.1007/s10750-009-9856-z

Stelzer, R.S., R.M. Bruch, H.G. Drecktrah, and M.P. Shupryt*.  2008. Carbon sources for lake sturgeon in  Lake Winnebago, WI.  Transactions of the American Fisheries Society 137:1018-1028.

Kent, T.R.* and R. S. Stelzer.  2008. Effects of deposited fine sediment on life history traits of Physa snails. Hydrobiologia 596:329-340.

Stelzer, R.S. and G. E. Likens. 2006. The effects of sampling frequency on estimates of dissolved silica export by streams: the role of hydrological variability and concentration-discharge relationships. Water Resources Research 42, W07415, doi:10.1029/2005WR004615, (10 pages).

Moe, S.J, R. S. Stelzer, M. R. Forman, W. S. Harpole, T. Daufresne, T. Yoshida. 2005. Recent advances in ecological stoichiometry: insights for population and community ecology. Oikos 109: 29-39.

Stelzer, R.S., J.B. Heffernan, and G.E. Likens. 2003. The Influence of dissolved nutrients and particulate organic matter quality on microbial respiration and biomass in a forest stream. Freshwater Biology 48: 1925-1937.

Stelzer, R.S. and G.A. Lamberti. 2002. Ecological stoichiometry in running waters: periphyton chemical composition and snail growth.  Ecology 83: 1039-1051.

Frost, P.C., R.S. Stelzer, G.A. Lamberti, and J.J. Elser.  2002.  Ecological stoichiometry of trophic interactions in the benthos: understanding the role of C:N:P ratios in littoral and lotic habitats.  Journal of the North American Benthological Society 21: 515-528.

Stelzer, R.S. and G.A. Lamberti. 2001. Effects of N:P ratio and total nutrient concentration on stream periphyton community structure, biomass, and elemental composition. Limnology and Oceanography 46: 356-367.