Research
My research focuses on the effects of invasive plant species in wetlands. I’m interested in how plant invasive species’ traits (such as rapid growth, large biomass, large litter deposition, and even genotype) trigger a cascade of effects that span from their interaction with co-occurring native species all the way up to ecosystem-level processes. I also combine molecular tools (microsatellite markers) to answer ecological questions, mostly related to the identification of hybridizing invasive plant species. I’m also interested in how ecological communities respond to external disturbances (e.g., invaders, pollutants, urbanization) and habitat restoration.
Projects and People
Grant-funded projects I'm part of
BRIDGE
CASA
ARCOS
ALRISE
Publications
*Denotes undergraduate student; **denotes graduate student
Geddes, P., L. Murphy*, Y. Astudillo-Scalia*, D. Blasini*, S. Nugent*, M. J. Rios*, A. Schirmer, and J. P. Olfelt. 2021. Microsatellite markers reveal unprecedented high frequencies of hybridization among Typha species in the Midwestern US. https://doi.org/10.1007/s13157-021-01429-2
Pini**, A.K. and P. Geddes. 2020. Fungi are capable of mycoremediation of river water contaminated with E. coli. Water, Air, and Soil Pollution 231:83. https://doi.org/10.1007/s11270-020-4464-7
Volesky**, L.A., S. Iqbal, J.J. Kelly, and P. Geddes. 2018. Relationships of native and exotic Phragmites australis to wetland ecosystem properties. Wetlands 38(3):577-589. DOI 10.1007/s13157-018-1001-1.
Geddes, P. 2015. Experimental evidence that subsidy quality affects the stability of recipient planktonic communities. Aquatic Sciences 77(4):609-621.
Geddes, P., T. Grancharova, J. J. Kelly, D. Treering, and N. C. Tuchman. 2014. Effects of invasive Typha x glauca on wetland ecosystem properties are influenced by time since invasion. Aquatic Ecology 48:247-258.
Lishawa, S.C., K.J. Jankowski, P. Geddes, D.J. Larkin, A.M. Monks, and N.C. Tuchman. 2014. Denitrification in a Laurentian Great Lakes coastal wetland invaded by hybrid cattail (Typha × glauca). Aquatic Sciences 76:483-495.
Larkin, D. M. Freyman, S. Lishawa, P. Geddes and N.C. Tuchman. 2011. Mechanisms of dominance by the invasive hybrid cattail Typha X glauca. Biological Invasions 14(1):65-77.
Mitchell, M.M, S. Lishawa , P. Geddes, D. Larkin, D. Treering, and N.C. Tuchman. 2011. Time-dependent impacts of cattail invasion in Great Lakes coastal wetlands. Wetlands 31:1143-1149.
Geddes, P. 2009. Decoupling carbon effects and UV protection from terrestrial subsidies on pond zooplankton. Hydrobiologia 628:47-66.
Tuchman, N. C., D. Larkin, P. Geddes, R. Wildova, K. Jankowski, and D. E. Goldberg. 2009. Patterns of environmental change associated with Typha x glauca invasion in a Great Lakes coastal wetland. Wetlands 29(3):964-975.
Chick, J. H., Geddes, P. and Trexler, J. C. 2008. Periphyton mat structure mediates trophic interactions in a subtropical marsh. Wetlands 28(2):378-389.
Tuchman, N. C., M. A. Schollett, S. T. Rier, and P. Geddes. 2006. Differential heterotrophic utilization of organic compounds by diatoms and bacteria under light and dark conditions. Hydrobiologia 561(1):167-177.
Leibold, M. A. and P. Geddes. 2005. El concepto de nicho en las metacomunidades. Ecología Austral 15:117-129.
Geddes, P. and J. C. Trexler. 2003. Uncoupling of omnivore-mediated positive and negative effects on periphyton mats. Oecologia 136:585-595.
Hermann, P. M., A. C. Curino, and P. Geddes. 2002. Comparative vegetative anatomy of Neosparton darwinii and N. ephedroides (Verbenaceae). Boletín de la Sociedad Argentina de Botánica 36:63-70.
Turner, A. M., Trexler, J. C., Jordan, F., Slack, S. J., Geddes, P., J. H. Chick, and W. F. Loftus. 1999. Targeting ecosystem features for conservation: Standing crops in the Florida Everglades. Conservation Biology 13:898-911.
Non-refereed publications
Geddes, P. 2019. The invasion of the cattails. Podcast. In Defense of Plants. http://www.indefenseofplants.com/podcast/2019/4/21/ep-209-invasion-of-the-cattails
Geddes, P. 2019. Too many cattails? An expert visits the Class of 1918 marsh. Friends of the Lakeshore Nature Preserve Newsletter. Preserve! 18(2):7. https://www.friendslakeshorepreserve.com/uploads/2/6/9/3/26931781/2019-spring-preserve-newsletter.pdf
Pantoja, A., P. Geddes, and J.C. Puentes. 2018. Conference on Catalyzing Progress in Undergraduate STEM Education: Insights from Midwestern HSIs. Medley, October issue, pages 1-2. Midwest Area Diversity and Equal Opportunity Council, Agricultural Research Service, United States Department of Agriculture. https://www.ars.usda.gov/ARSUserFiles/50000000/Medley/MedleyOct2018.pdf