Loyola University Chicago

Department of Biology

Timothy Hoellein


  Assistant Professor
Ph.D. 2008, University of Notre Dame
Aquatic Ecologist
Phone: 773.508.8859
Fax: 773.508.3646
E-mail: thoellein@luc.edu


Ecosystem processes and biogeochemistry; the use of metrics of ecosystem function and seasonal dynamics for evaluation of human impacts and restoration in aquatic ecosystems. Currently I am conducting research projects related to the influence of restoration on N cycling in eutrophic coastal habitats in NYC, measuring the role of freshwater bivalves on N transformations, and analyses of biofilm activity on anthropogenic litter and microplastic in aquatic ecosystems.

Representative Publications (*undergraduate students, §graduate students)

§Lindeman, S., Castignetti, D., Zarnoch, C.B., and T.J. Hoellein. In Press. Effect of eastern oysters (Crassostrea virginica) and seasonality on nitrite reductase gene abundance (nirS, nirK, nrfA) in an urban estuary. Estuaries and Coasts

§Turek, K.A., and T.J. Hoellein. 2015. The invasive Asian clam (Corbicula fluminea) increases sediment denitrification and ammonium flux in 2 streams in the Midwestern USA.  Freshwater Science 34(2): 472-484

Hoellein, T.J., *Westhoven, M., Lyandres, O., and J. Cross. 2015. Abundance and environmental drivers of anthropogenic litter on 5 Lake Michigan beaches: A study facilitated by citizen science data collection. Journal of Great Lakes Research. 41:78-86

Hoellein, T.J., Zarnoch, C.B., and R. Grizzle.  2015. Water quality influences on eastern oyster (Crassostrea virginica) feeding, biodeposition, and sediment N cycling in Great Bay, NH. Biogeochemistry 122(1): 113-129

§McCormick, A., Hoellein, T.J., Mason, S., Schluep, J., and J.J. Kelly. 2014. Microplastic in an abundant and district microbial habitat in an urban river. Environmental Science and Technology. 48(20):11863-71.

Richardson, D.C., *Oleksy, I.A., Hoellein, T.J., Arscott, D. B., Gibson, C.A., and S.M. *Root.  2014. Spatial distribution and macroinvertebrate community effects of a nuisance, bloom-forming diatom (Didymosphenia geminata) in Catskill Mountain streams, New York.  Aquatic Sciences 76(4):553-564

Hoellein, T.J., §Rojas, M., *Pink, A. *Gasior, J., and J. J. Kelly. 2014. Anthropogenic litter in urban freshwater ecosystems: Distribution and microbial interactions.  PLoS One 9(6): e98485

Hoellein, T.J., and C.B. Zarnoch. 2014. Effect of eastern oysters (Crassostrea virginica) on sediment carbon and nitrogen dynamics in an urban estuary. Ecological Applications 24(2):271-286

Hoellein, T.J., Bruesewitz, D.A., and D. Richardson.  2013. Revisiting Odum (1956): A synthesis of aquatic ecosystem metabolism.  Limnology and Oceanography.  58(6), 2013, 2089–2100.

Hoellein, T.J., J.L. Tank, S.A. Entrekin, E.J. Rosi-Marshall, M.L. Stephen, and G.A. Lamberti. 2012. Effects of a benthic habitat restoration on nutrient uptake and ecosystem metabolism in three headwater streams.  River Research and Applications. 28 (9): 1451-1461

Hoellein. T.J., Bruesewitz, D.A., and D.P. Hamilton. 2012. Are geothermal streams important sites of nutrient uptake in an agricultural and urbanizing landscape (Rotorua, New Zealand)? Freshwater Biology 57: 129–142

Hoellein, T.J, Arango, C.P., and Y. Zak*. 2011. Spatial variability in nutrient concentration and limitation in an urban watershed (Bronx River, New York, USA). Biogeochemistry 106:265–280

Hoellein, T.J.,  J.L. Tank, J.J. Kelly, and E.J. Rosi-Marshall. 2010. Seasonal variation in nutrient limitation of microbial biofilms colonizing organic and inorganic substrata in streams. Hydrobiologia 649:331-345

Kominoski, J.S., T.J. Hoellein, C.J. Leroy, C.M. Pringle, and C.M. Swan.  2010.  Beyond species richness: expanding biodiversity-ecosystem functioning theory in detritus-based streams. River Research and Applications. 26: 67-75.

Hoellein, T.J., J.L. Tank, E.J. Rosi-Marshall, and S.A. Entrekin. 2009. Temporal variation in substratum-specific rates of N uptake and metabolism and their relative contribution at the reach scale.  Journal of the North American Benthological Society. 28(2): 305-318.

Entrekin, S.A., J.L. Tank, E.J. Rosi-Marshall, T.J. Hoellein, and G.A. Lamberti. 2009. Responses in macroinvertebrate secondary production to large wood addition in three Michigan streams.  Freshwater Biology 54 (8): 1741-1758.

Kominoski, J.S., T.J. Hoellein, J.J. Kelly, and C. M. Pringle. 2009. Does mixing litter of different qualities alter stream microbial diversity and functioning on individual litter species? Oikos. 118:457-463.

Entrekin, S.A., J.L. Tank, E.J. Rosi-Marshall, T.J. Hoellein, and G.A. Lamberti. 2008. Responses in organic matter accumulation and processing to an experimental wood addition in three headwater streams. Freshwater Biology 53:1642–1657.

Hoellein, T.J., J.L. Tank, E.J. Rosi-Marshall, S.A. Entrekin, and G.A. Lamberti. 2007. Controls on spatial and temporal variation of nutrient uptake in three Michigan headwater streams.  Limnology and Oceanography 52 (5) 1964-1977. 

Entrekin, S.A., E.J. Rosi-Marshall, J.L. Tank, T.J. Hoellein, and G.A. Lamberti. 2007. Macroinvertebrate secondary production in forested sand-bottom streams of the Upper Midwest.  Journal of the North American Benthological Society. 26 (3): 472-490.