Cohn is interested in understanding the ways in which cells can respond to changes in environmental conditions (e.g. light, temperature, water conditions) that allow them to remain ecologically successful. Specifically, his lab works with diatoms, a ubiquitous form of unicellular algae that exists in almost all freshwater and marine environments, and one of the few kinds of organisms that can successfully incorporate silicon, using it to form a hardened siliceous cell wall. While many forms of diatoms are planktonic, Cohn works with sediment dwelling diatoms (i.e. benthic) that are able to move by a mucilage-based gliding mechanism. This gliding is regulated, for example allowing the cells to move into light regions (for energy) or out of the light (to avoid photodamage or to provide for better refuge). The lab uses several kinds of microscopic observations and treatments to understand how characteristics and changes in light, surface, population, and water conditions affect and help regulate the ability of different diatom species to move and adhere.

Cohn, S.A., Bahena, M., Davis, J.T., Ragland, R.L., Rauschenberg, C.D. & Smith, B.J. (2004) Characterisation of the diatom photophobic response to high irradiance. Diatom Research 19:167-179. Cohn, S.A., Halpin, D., Hawley, N., Ismail, A., Kaplan, Z., Kordes, T., Kuhn, J., Macke, W., Marhaver, K., Ness, B., Olszewski, S., Pike, A., Rice, E., Sbarboro, J., Wolske, A. & Zapata, Y. (2015) Comparative analysis of light-stimulated motility responses in three diatom species. Diatom Research 30:213-225. Cohn, S.A., Dunbar, S., Ragland, R., Schulze, J., Suchar, A., Weiss, J. and Wolske, A. (2016) Analysis of Light Quality and Assemblage Composition on Diatom Motility and Accumulation Rate. Diatom Research (in press, published online DOI:10.1080/0269249X.2016.1193058)?.