Janet M Fischer Dr. E. Paul & Frances H. Reiff Professor of Biology, Department Chair of Biology

Limnology; Ecology of Alpine Lakes; Ecosystem Resilience; Zooplankton.



B.A. Wellesley College

M.S., Ph.D. University of Wisconsin


Please see the Fischer-Olson Lab website for more information about research


Research with Students

Academic Friendship: The Story of Nora and Janet, featuring Nora Theodore Hwang '13 and Prof. Janet Fischer

Selected Publications

Weyhenmeyer, G.A., U. Obertegger, H. Rudebeck, E. Jakobsson, J. Jansen, G. Zdorovennova, S. Bansal, B. Block, C.C. Carey, J.P. Doubek, H. Dugan, O. Erina, I. Fedorova, J.M. Fischer, L. Grinberga, H-P. Grossart, K. Kangur, L.B. Knoll, A. Laas, F. Lepori, J. Meier, N. Palshin, M. Peternell, M. Pulkkanen, J.A. Rusak, S. Sharma, D. Wain, and R. Zdorovennov.  2022.  Towards critical white ice conditions in lakes under global warming.  Nature Communications 13:4974.
Olson, M.H., J.M. Fischer, and M. Hayashi.  2022.  Temporal dynamics of dissolved organic matter (DOM) in mountain lakes: the role of catchment characteristics.  Canadian Journal of Fisheries and Aquatic Sciences 79: 289-299.

Beaulieu, J., D. Trepanier-Leroux, J. M. Fischer, M. H. Olson, S. Thibodeau, S. Humphries, D. J. Fraser & A. M. Derry.  2021.  Rotenone for exotic trout eradication: nontarget impacts on aquatic communities in a mountain lake, Lake and Reservoir Management, DOI: 10.1080/10402381.2021.1912864

Olson, M.H., J.M. Fischer, M. Hayashi, and C.E. Williamson.  2020.  Meteorological drivers of interannual variation in transparency of mountain lakes.  Arctic, Antarctic, and Alpine Research 52(1): 424-434.

Loewen, C.J.G., A. L. Strecker, G.L. Larson, A. Vogel, J.M. Fischer, and R.D. Vinebrooke.  2018.  Macroecological driver of zooplankton communities across the mountains of western North America.  Ecography DOI 10.1111/ecog.03817

Olson, M.H., J.M. Fischer, C.E. Williamson, E.P. Overholt, and N. Theodore*.  2018.  Landscape-scale regulators of water transparency in mountain lakes: implications of projected glacial loss.  Canadian Journal of Fisheries and Aquatic Sciences 75: 1169-1176.

Overholt EP, KC Rose, CE Williamson, JM Fischer, NA Cabrol. 2016. Behavioral responses of freshwater calanoid copepods to the presence of ultraviolet radiation: avoidance and attraction. Journal of Plankton Research 38: 16-26.

Sanders RW, SL Cooke, JM Fischer, SB Fey, AW Heinze, WH Jeffrey, AL Macaluso, RE Moeller, DP Morris, PJ Neale, MH Olson, JD Pakulski, JA Porter, DM Schoener, and CE Williamson. 2015. Shifts in microbial food web structure and productivity after additions of naturally occurring dissolved organic matter: results from large-scale lacustrine mesocosms. Limnology and Oceanography 60: 2130-2144.

Cooke SL, JM Fischer, K Kessler, CE Williamson, RW Sanders, DP Morris, JA Porter, and W Jeffries. 2015. Direct and indirect effects effects of additions of chromophoric dissolved organic matter during large-scale mesocosm experiments in an oligotrophic lake. Freshwater Biology 60: 2362-2378.

Leach TH, CE Williamson, N Theodore*, JM Fischer, and MH Olson. 2015. The role of ultraviolet radiation in the diel vertical migration of zooplankton: an experimental test of the transparency-regulator hypothesis. Journal of Plankton Research 37: 886-896.

Fischer JM, MH Olson, N Theodore*, CE Williamson, KC Rose, and J Hwang*. 2015. Diel vertical migration of copepods in mountain lakes: the changing role of ultraviolet radiation across a transparency gradient. Limnology and Oceanography 60: 252-262.

Rose KC, DP Hamilton, CE Williamson, C McBride, JM Fischer, MH Olson, JE Saros, MG Allan, N Cabrol. 2014. Comparison of light attenuation characteristics between glacially- and non-glacially fed lakes. Journal of Geophysical Research: Biogeosciences 119, doi:10.1002/2014JG002674.

Rose KC, CE Williamson, JM Fischer, SJ Connelly, MH Olson, AJ Tucker, DA Noe. 2012.The role of ultraviolet radiation and fish in regulating the vertical distribution of Daphnia.  Limnology and Oceanography 57: 1867-1876.

Fischer JM, MH Olson, CE Williamson, JC Everhart*, PJ Hogan, JA Mack, KC Rose, JE Saros, JR Stone, RD Vinebrooke. 2011. Implications of climate change for Daphnia in alpine lakes: predictions from long-term dynamics, spatial distribution, and a short-term experiment.  Hydrobiologia 676: 263-277.

Williamson CE, JM Fischer, SM Bollens, EP Overholt, and JK Breckenridge. 2011. Toward a more comprehensive theory of zooplankton diel vertical migration: integrating ultraviolet radiation and water transparency into the biotic paradigm. Limnology and Oceanography 56: 1603-1623.

Rose KC, CE Williamson, JE Saros, R Sommaruga, and JM Fischer. 2009. Differences in UV transparency and thermal structure between alpine and subalpine lakes: Implications for organisms. Photochem. Photobiol. Sci 8: 1244-1256.

Course Information

101. Ecology & Evolutionary Biology

An introduction to Mendelian genetics, micro- and macro-evolutionary processes, the origin and diversification of life on earth and ecological patterns and processes at organismal, population, community and ecosystem levels. Offered every Spring. 

310. Experimental Design in Biology. (BWR)

An exploration of the challenges and rewards of experimentation in biology. In this seminar, we will use case studies to illustrate the basic principles of experimental design, including hypothesis generation, assigning treatments, replication/pseudoreplication, confounded variables and statistical power. Case studies will be chosen to represent a wide range of sub-disciplines of biology, including biomedical research. Prerequisites: BIO 210, 200 or 220 and permission of the instructor. 

323. Ecological Concepts and Applications. (N) (BWR)

Interactions of organisms with their environment and how these interactions are influenced by human activities. Special emphasis is placed on principles of population, community and ecosystem ecology. Class exercises and discussions involve critical evaluation of current research and applications of ecological concepts to conservation and management. Most labs are field-oriented, including an overnight trip to the Poconos. Prerequisites: BIO 200 or 220 and permission of the instructor. Offered every Fall.