Professor emeritus, Department of Biological Sciences
University of Notre Dame
Bio:
Education:
B.B.A. University of Notre Dame 1972
M.F.S. Yale University 1974
Ph.D. Harvard University 1978
Post-doctoral appointments:
Harvard Society of Fellows (1976 – 1980)
University of Washington (1978-1980)
Faculty Positions:
1980 – 1992 University of Michigan
1992 – 2001 Utah State University
2001 – 2019 Gillen Director, University of Notre Dame Environmental Research Center
Research at National Bison Range, MT (1978 – 2019).
Research on Great Salt Lake, UT since 1994.
Title: Modeling Great Salt Lake Nitrogen Cycling
Abstract: Nitrogen limits production of phytoplankton and microbialite primary producers in Great Salt Lake, which in turn limits the abundance of brine shrimp and brine fly larvae that attract abundant waterbirds. Therefore, nitrogen cycling is critical for understanding the lake’s ecology. Nitrogen cycling has been incorporated into the Great Salt Lake food-web model that has previously been presented here. To accomplish this, each food-web component’s tissue and excrement nitrogen content, production rate, death rate, and decomposition rate were measured. The model is then solved for monthly nitrogen in the water column within a year and between years, which is compared to the observed lake value and found to be similar. Brine shrimp fecal pellets were identified as a major component of the nitrogen cycle. The fecal pellets decompose slowly and sink rapidly, which largely leads to benthic deposition on microbialites or deeper. If deposited on microbialites, fecal pellets can be consumed by brine fly larvae, which accelerates their nitrogen release to the water column or supports high primary production by microbialites. If deposited deeper, fecal pellets release their nitrogen very slowly into the water column or even more slowly if a deep brine layer exists and the pellets enter it.