Lesley Knoll

Lesley Knoll

Assistant Professor

194 Pearson Hall (office) 153 Pearson Hall (lab)
Lab website  Google scholar link 

Biographical Information

I am a freshwater ecologist and my research focuses broadly on how global change affects freshwater systems. My research is highly collaborative and aims to protect water resources facing multiple stressors such as climate change, land use change, and invasive species. Many of my research questions focus on understanding how environmental change acts alone or in combination to regulate aquatic ecosystem function (e.g., primary production, carbon and nutrient fluxes, anoxia) and structure (e.g., phytoplankton composition, toxic cyanobacteria). I use a variety of approaches and methods in my research including conducting large-scale field surveys, using large long-term datasets, implementing field and lab experiments, and making use of advanced aquatic sensors.

Current research areas include:

  • The impact of warming winters on lake dynamics, and carryover effects into the summer. Over the past 150 years, the winter season in the Northern Hemisphere has dramatically changed with shorter seasonal lake ice cover duration and changes in the amount and type of precipitation. Recent work by myself and collaborators highlights that lakes are biologically active in the winter, that what happens in the winter can shape lake dynamics in the summer, and that lakes provide important cultural ecosystem services to people during the winter.
  • Combined stressors and coldwater fish habitat. Coldwater fisheries are threatened by anthropogenic stressors (e.g., climate change, eutrophication, and invasive species), and we do not understand the magnitude of these stressors on hypolimnetic oxygen in lakes in the Midwest US or if lakes with different characteristics (e.g., geographic position, morphometry) respond to these stressors differently. Current work, in collaboration with the Minnesota Department of Natural Resources, is examining this pattern across gradients of climate (MN, WI, MI) and lake characteristics.

Course Taught

  • BIO 209: Fundamental of Ecology
  • BIO 672: Ecosystem and Global Ecology
  • BIO 710: Graduate seminar

Selected Publications

  • Weyhenmeyer, G.A., U. Obertegger, H. Rudebeck, [and 25 others including L.B. Knoll]. 2022.Towards critical white ice conditions in lakes under global warming. Nature Communications 13, 4974. https://doi.org/10.1038/s41467-022-32633-1

  • Sharma, S., A. Filazzola, T. Nguyen, M. Arshad Imrit, K. Blagrave, [and 32 others including L.B. Knoll]. 2022. Long-term ice phenology records spanning up to 578 years for 78 lakes around the Northern Hemisphere. Scientific Data, 9, 318. https://doi.org/10.1038/s41597-022-01391-6

  • Hrycik, A.R., P.D.F. Isles, R. Adrian, M. Albright, L.C. Bacon, S.A. Berger, R. Bhattacharya, H.P. Grossart, J. Hejzlar, A.L. Hetherington, L.B. Knoll, A. Laas, C.P. McDonald, K. Merrell, J.C. Nejstgaard, K. Nelson, P. Noges, A.M. Paterson, R.M. Pilla, D.M. Robertson, L.G. Rudstam, J.A. Rusak, S. Sadro, E.A. Silow, J. Stockwell, H. Yao, K. Yokata, and D.C. Pierson. 2021. Earlier winter/spring runoff and snowmelt during warmer winters lead to lower summer chlorophyll-a in north temperate lakes. Global Change Biology. DOI: 10.1111/gcb.15797

  • Stetler, J.T., L.B. Knoll, C.T. Driscoll, and K.C. Rose. Lake browning generates aspatiotemporal mismatch between DOC and limiting nutrients. 2021. Limnology and Oceanography Letters. doi: 10.1002/lol2.10194

  • Jane, S.F., G.J.A. Hansen, B.M. Kraemer, [and 38 others including L.B. Knoll]. 2021.Widespread deoxygenation of temperate lakes. Nature 594: 66-70.

  • Kraemer, B.M., R.M Pilla, R.I. Woolway, [and 33 others including L.B. Knoll]. 2021. Climatechange drives widespread shifts in lake thermal habitat. Nature Climate Change 11: 521-529.

  • Sharma, S., K. Blagrave, S.R. Watson, C. O’Reilly, R. Batt, J.J. Magnuson, T. Clemens, B.A. Denfeld, G. Flaim, L. Grinberga, Y. Hori, A. Laas, L.B. Knoll, D. Straile, N. Takamura, and G.A. Weyhenmeyer. 2020. Increased winter drownings in ice-covered regions with warmer winters. PLOS One 15: e0241222. doi: 10.1371/journal.pone.0241222

  • Knoll, L.B., S. Sharma, B.A. Denfeld, G. Flaim, Y. Hori, J.J. Magnuson, D. Straile, and G.A.Weyhenmeyer. 2019. Consequences of lake and river ice loss on cultural ecosystem services. Limnology and Oceanography Letters 4: 119-131.

  • Block, B., B.A. Denfeld, J.D. Stockwell, G. Flaim, H.P.F. Grossart, L.B. Knoll, D.B. Maier, R.L. North, M. Rautio, J.A. Rusak, S. Sadro, G.A. Weyhenmeyer, A.J. Bramburger, D.K. Branstrator, and S.E. Hampton. 2019. The unique methodological challenges of winter limnology. Limnology and Oceanography Methods 17: 42-57 doi: 10.1002/lom3.10295

  • Knoll, L.B., C.E. Williamson, R.M. Pilla, T.H. Leach, J.A. Brentrup, and T.J. Fisher. 2018. Browning-related oxygen depletion in an oligotrophic lake. Inland Waters 8: 255-263.

  • Richardson, D.C., S.J. Melles, R.M. Pilla, A.L. Hetherington, L.B. Knoll, C.E. Williamson, B.M. Kraemer, J.R. Jackson, E.C. Long, K. Moore, L.G. Rudstam, J.A. Rusak, J.E. Saros, S. Sharma, K.E. Strock, K.C. Weathers, and C.R. Wigdahl-Perry. 2017. Transparency, geomorphology, and mixing regime explain variability in trends in lake temperature and stratification across northeastern North America (1975 – 2014). Water 9: 442. doi:10.3390/w9060442

  • Knoll, L.B., A. Morgan, M.J. Vanni, T.H. Leach, T.J. Williamson, and J.A. Brentrup. 2016.Quantifying pelagic phosphorus regeneration using three methods in lakes of varying productivity. Inland Waters 6: 509-522.

  • Knoll, L.B., M.J. Vanni, W.H. Renwick, and S. Kollie. 2014. Burial rates and stoichiometry of sedimentary carbon, nitrogen and phosphorus in Midwestern US reservoirs. Freshwater Biology 59: 2342-2353.

  • Knoll, L.B., M.J. Vanni, W.H. Renwick, E.K. Dittman, and J.A. Gephart. 2013. Temperate reservoirs are large carbon sinks and small CO2 sources: Results from high-resolution carbon budgets. Global Biogeochemical Cycles 27: 52-64.

  • White, J.D., R.B. Kaul, L.B. Knoll, A.E. Wilson, and O. Sarnelle. 2011. Large variation in vulnerability to grazing within a population of the colonial phytoplankter, Microcystis aeruginosa. Limnology and Oceanography 56: 1714-1724.

  • Tranvik, L.J., J.A. Downing, J.B. Cotner, S.A. Loiselle, R.G. Striegl, T.J. Ballatore, P. Dillon, K. Finlay, K. Fortino, L.B. Knoll, P.L. Kortelainen, T. Kutser, S. Larsen, I. Laurion, D.M. Leech, S.L. McCallister, D.M. McKnight, J.M. Melack, E. Overholt, J.A. Porter, Y. Prairie, W.H. Renwick, F. Roland, B.S. Sherman, D.W. Schindler, S. Sobek, A. Tremblay, M.J. Vanni, A.M Verschoor, E. von Wachenfeldt, and G.A. Weyhenmeyer. 2009. Lakes and reservoirs as regulators of carbon cycling and climate. Limnology and Oceanography 54: 2298-2314.

  • Knoll, L.B., O. Sarnelle, S.K. Hamilton, C.E.H. Kissman, A.E. Wilson, J.B. Rose, and M.R.Morgan. 2008. Invasive zebra mussels (Dreissena polymorpha) increase cyanobacterial toxin concentrations in low-nutrient lakes. Canadian Journal of Fisheries and Aquatic Sciences 65: 448-455.