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Megan Rohrssen

​Assistant Professor
Geology and Environmental Sciences
Brooks Hall 319
989-774-2079
megan.rohrssen@cmic​h.edu
​​Education
  • ​​Ph.D., Earth Science, University of California, Riverside, 2013
  • B.A., Geology, Carleton College, 2007
Professional Interests
Organic geochemistry, geobiology, biogeochemistry 

Microbial communities and primary producers form the basis of food webs and are central to cycling of essential macro- and micronutrients. How these ecosystems functioned under baseline conditions and responded to environmental perturbations in the past can help us anticipate how such ecosystems may behave under future conditions. However, these organisms are difficult to study in the past because single-celled, shell-less bacteria, archaea, and algae are seldom preserved or identified in sediments and rocks. Fortunately, organisms produce a suite of biochemicals – biomarkers - that have good preservation potential and can be linked to their source organism or conditions. The study of these molecules is termed organic geochemistry, which is my primary research tool. I use organic geochemistry to investigate the interactions of microbial communities with past biogeochemical and climatic events throughout the co-evolutionary history of life and the Earth (a.k.a. "geobiology"). Applications of my field beyond geobiology include tracing sources and preservation of sedimentary organic matter, paleoclimate proxies, and the fingerprinting and tracking of petroleum-derived pollutants in recent sediments and the subsurface. At CMU, I am continuing my projects in Paleozoic geobiology, but also planning to expand my work in modern lakes, wetlands, and culturing in order to better inform interpretation of past lake and wetland biogeochemistry. 
Teaching Areas
  • ​GEL 105 Dangerous Planet
  • GEL 100 Introduction to Earth Systems​
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Selected Publications
  • Owens, J.D., Reinhard, C.T., Rohrssen, M., Love, G.D., Lyons, T.W., "Empirical links between trace metal cycling and marine microbial ecology during a large perturbation to Earth's carbon cycle." Accepted, Earth and Planetary Science Letters 2016, 449, pp. 407-417. DOI: 10.1016/j.epsl.2016.05.046.
  • Matheus Carnevali, P., Rohrssen, M., Williams, M.R., Michaud, A.B., Adams, H., Berisford, D., Love, G.D., Priscu, J.C., Rassuchine, O., Hand, K.P., Murray, A.E., "Methane sources in arctic thermokarst lake sediments on the North Slope of Alaska." Geobiology 2015, 13, (2) pp. 181-197. DOI: 10.1111/gbi.12124.
  • Rohrssen, M., Gill, B., Love, G.D., "Scarcity of the 'marine biomarker' 24-n-propylcholestane in Lower Paleozoic marine paleoenvironments." Organic Geochemistry 2015, 80, pp. 1-7.
  • Rohrssen, M., Love, G., Fisher, W., Finnegan, S., Fike, D.A. "Lipid biomarkers record fundamental changes in microbial community structure of tropical seas during the Late Ordovician Hirnantian Glaciation." Geology 2013, 41 (2) pp. 127-130. DOI: 10.1130/G33671.1.​