Steven Thomas

Steven Thomas

  • Contact Information
  • My Story
  • Publications
  • Background
  • Interests
  • Grants
  • Advising
  • Courses Taught

Contact Information

TitleRiver/Stream Ecologist
Faculty RankProfessor
Address403 South Hardin Hall
3310 Holdrege Street
Lincoln NE
  • office: 402-613-0043
  • fax: 402-472-2946
VitaeDownload file


Contact Preference

email, phone

Office Hours


My Story

Hi, I'm Steven Thomas, a river/stream ecologist with the School of Natural Resources.

Simply put, I'm interested in understanding how the properties of one location impact the ecological properties of another. The flow of water links upstream and downstream habitats, and longitudinal connection is a fundamental, though often ignored, aspect of ecology.

Steven Thomas

My research combines ecology and hydrology to address nutrients in streams, microbiological activity, and organic matter production, transport and processing.

These interests have led me to research topics such as organic particle dynamics in stream ecosystems, in-stream nitrogen removal and transport; hydrology, remote sensing and thermal heterogeneity in floodplain river ecosystems; flow paths and the formation of biogeochemical hotspots; and other areas.

My research is nested within the broader intellectual pursuit of understanding landscape integration at the watershed scale.

I came to UNL as an assistant professor of stream ecology in January 2006. Previously, I've been a postdoctoral fellow at Cornell University and formerly a research hydrologist in the private sector.

I've taught at the graduate and undergraduate levels in biology, limnology and the use of stable isotopes in ecology, among other topics.

Selected Publications

Caniglia, J., Snow, D., Messer, T., Bartelt-hunt, S., & Thomas, S. A. (2022). Occurrence of Per- and Polyfluoroalkyl Substances (PFAS) in wastewater treatment , wastewater biosolids and after biosolids land application to determine agroecosystem loading. Frontiers in Environmental Water Quality.
Myrstener, M., Thomas, S.A., Giesler, R., Sponseller, R.A. 2021. Nitrogen supply and physical disturbance shapes Arctic stream nitrogen uptake through effects on metabolic activity. Freshwater Biology. 66: 1502-1514. DOI: 10.1111/fwb.13734Online
Silva-Araujo, M., Silva-Junior, E.F., Neres-Lima, V., Feijo-Lima, R., Tromboni, F., Lourenco-Amorim, C., Thomas, S.A., Moulton, T.P. 2020. Effects of Riparian Deforestation on Benthic Invertebrate Community and Leaf Processing in Atlantic Forest Streams. Perspectives in Ecology and Conservation. 18:277-282.Online
Atkinson, C. L., Alexiades, A. V., MacNeill, K. L., Encalada, A. C., Thomas, S., Flecker, A. S. 2019. Nutrient recycling by insect and fish communities in high-elevation tropical streams. Hydrobiologia. 838(1): 13-28.Online
Fernandes Cunha, Davi Gasparini, Finkler, N. R., Gomez, N., Cochero, J., Donadelli, J. L., Saltarelli, W. A., Calijuri, Maria do Carmo, Poli Miwa, Adriana Cristina, Tromboni, F., Dodds, W. K., Boechat, I. G., Gucker, B., Thomas, S. 2019. Agriculture influOnline
Simon, T. N., Binderup, A. J., Flecker, A. S., Gilliam, J. F., Marshall, M. C., Thomas, S., Travis, J., Reznick, D. N., Pringle, C. M. 2019. Landscape patterns in top-down control of decomposition: omnivory disrupts a tropical detrital-based trophic cascaOnline
Tromboni, F., Lourenco-Amorim, C., Neres-Lima, V., Thomas, S., Silva-Araujo, M., Feijo-Lima, R., Silva-Junior, E. F., Heatherly, Thomas, II, Moulton, T. P., Zandona, E. 2019. Conversion of tropical forests to agriculture alters the accrual, stoichiometry,Online
Atkinson, C., Rugenski, A., Encalada, A., Thomas, S., Landiera-Dabarca, A., Poff, L., Flecker, A. (2018). Determinants of food resource assimilation by stream insects along a tropical elevation gradient. Oecologia, 187(3).
Feijo de Lima, r., Feijo-Lima, R., McCleay, S., Silva-Junior, E. F., Tromboni, F., Moulton, T. P., Zandona, E., Thomas, S. (2018). Quantitatively describing the downstream effects of an abrupt land cover transition: buffering effects of a forest remnant o
Polato, N. R., Gill, B. A., Shah, A. A., Gray, M. M., Casner, K. L., Barthelet, A., Messer, P. W., Thomas, S., Guayasamin, J. M., Encalada, A. C., Kondratieff, B. C., Flecker, A. S., Poff, L., Ghalambor, C. K., Funk, W. C., Zamudio, K. R. (2018). Narrow t
Tromboni, F., Thomas, S., Lourenço-Amorim, C., Gücker, B., Moulton, T. P., Silva-Junior, E. F., Feijó De Lima, R., Boëchat, I. G., Neres-Lima, V., Zandonà., E. (2018). Nutrient limitation and the stoichiometry of nutrient uptake in a tropical rainforest s
Bookshire, E.N.J., S. Gerber, W. Greene, R.A. Jones, and S.A. Thomas. 2017. Plant uptake and stream chemistry set global bounds on nitrogen gas emissions from humid tropical forests. Geophysical Research Letters doi: 10.1002/2017GL072867Online
Loecke, T., Burgin, A., Riveros Iregui, D., Thomas, S., Ward, A., Davis, C., St.Clair, M. (2017). Weather whiplash in agricultural regions drives deterioration of water quality. Biogeochemistry, 133(1), 7-15.Online
Norman, B., Whiles, M., Collins, S., Flecker, A., Hamilton, S., Thomas, S., Webster, J. (2017). Drivers of nitrogen transfer efficiencies in stream food webs across continents. Ecology.Online
Shah, A. A., Gill, B. A., Encalada, A. C., Flecker, A. S., Funk, W. C., Guyasamin, J. M., Kondratieff, B. C., Poff, N. L., Thomas, S., Zamudio, K. R., Ghalambor, C. K. (2017). Climate variability predicts thermal limits of aquatic insects across elevationOnline
Simon, T. N., Bassar, R. D., Binderup, A. J., Flecker, A. S., Freeman, M. C., Gilliam, J. F., Marshall, M. C., Thomas, S., Travis, J., Reznick, D. N., Pringle, C. M. (2017). Experimental evidence that local adaptation in Trinidadian Guppies alters ecosystOnline
Tank, J., Eugènia Martí, A. R., Dodds, W., Whiles, M., Thomas, S., Webster, J. (2017). Partitioning assimilatory nitrogen uptake in streams: an analysis of stable isotope tracer additions across continents. Ecological Monographs, 88, 120-138.Online
Zandona, E., Dalton, C. M., El-Sabaawi, R. W., Howard, J. L., Marshall, M. C., Kilham, S. S., Reznick, D. N., Travis, J., Kohler, T. J., Flecker, A. S., Thomas, S., Pringle, C. M. (2017). Population variation in the trophic niche of the Trinidadian guppy Online
Collins, S. M., Sparks, J. P., Thomas, S., Wheatley, S. M., Flecker, A. S. (2016). Increased Light Availability Reduces the Importance of Bacterial Carbon in Headwater Stream Food Webs. Ecosystems. 19: 396-410.Online
Collins, S. M., Thomas, S., Heatherly, T. N., MacNeill, K., Leduc, A., Lamphere, B., Reznick, D. N., Pringle, C., Flecker, A. S. 2016. Fish introductions and light modulate food web fluxes in tropical streams: a whole-ecosystem experimental approach. EcolOnline
Gill, B. A., Kondratieff, B. C., Casner, K. L., Encalada, A. C., Flecker, A. S., Gannon, D. G., Ghalambor, C. K., Guaysamin, J. M., Poff, N. L., Simmons, M. P., Thomas, S., Zamudio, K. R., Funk, W. C. 2016. Cryptic species diversity reveals biogeographic Online
Lessmann, J., Guayasamin, J. M., Casner, K. L., Flecker, A. S., Funk, W. C., Ghalambor, C. K., Gill, B. A., Jacome-Negrete, I., Kondratieff, B. C., Poff, N. L., Schreckinger, J., Thomas, S., Toral-Contreras, E., Zamudio, K. R., Encalada, A. C. 2016. FreshOnline
Reynolds, K. N., Loecke, T. D., Burgin, A. J., Davis, C. A., Riveros - Iregui, D., Thomas, S., St Clair, M. A., Ward, A. S. 2016. Optimizing sampling strategies for riverine nitrate using high-frequency data in agricultural watersheds. Environmental ScienOnline
Bassar, R. D., Heatherly, T. N., Marshall, M. C., S. A., Flecker, A. S., Reznick, D. N. (2015). Population size-structure-dependent fitness and ecosystem consequences in Trinidadian guppies. Journal of Animal Ecology, 84, 955-968.Online
Collins, S. M., Kohler, T. J., Thomas, S., Fetzer, W. W., Flecker, A. S. 2015. The importance of terrestrial subsidies in stream food webs varies. Oikoa Synthesising ecology. 125:674-685.Online
El Sabaawi, R., Bassar, R. D., Raskowski, C., Marshall, M. C., Bryan, B. L., Thomas, S., Pringle, C., Reznick, D. N., Flecker, A. S. (2015). Intraspecific phenotypic differences in fish affect ecosystem processes as much as bottom – up factors. Oikos. 124Online
Goodale, C. L., Fredriksen, G., Wiess, M. S., McCalley, C. K., Sparks, J. P., Thomas, S. (2015). Soil processes drive seasonal variation in retention of 15N tracers in a deciduous forest catchment. , 96(10), 2653–2668.Online
Davis, C., Ward, A., Burgin, A., Loecke, T., Riveros Iregui, D., Schnoebelen, D., Just, C., Thomas, S., Weber, L., St.Clair, M. (2014). Antecedent moisture controls on stream nitrate flux in an agricultural watershed, Clear Creek, Iowa. Journal of Environ
Brookshire, E. N., Thomas, S. (2013). Ecosystem Consequences of Tree Monodominance for Nitrogen Cycling in Lowland Tropical Forest. PLoS One, 8, e70491.Online
Cheever, B. M., Webster, J. R., Bilger, E. E., Thomas, S. (2013). The relative importance of exogenous and substrate-derived nitrogen for microbial growth during leaf decomposition. Ecology, 94, 1614-1625.Online
Auer, S., Lopez-Sepulcre, A., Heatherly, T. N., Kohler, T. J., Bassar, R. D., Thomas, S., Reznick, D. N. (2012). Life histories have a history: Effects of past and present conditions on adult somatic growth rates in wild Trinidadian guppies. Journal of AnOnline
El-Sabaawi, R., Kohler, T. J., Zandona, E., Travis, J., Marshall, M. C., Thomas, S., Reznick, D. N., Walsh, M., Gilliam, J. F., Pringle, C. P., Flecker., A. S. (2012). Environmental and Organismal Predictors of Intraspecific Variation in Stoichiometry of Online
Kohler, T. J., Heatherly, T. N., El-Sabaawi, R. W., Zandonà, E., Marshall, M. C., Flecker, A. S., Pringle, C. M., Reznick, D. N., Thomas, S. (2012). Flow, nutrients, and light availability influence Neotropical epilithon biomass and stoichiometry. Freshwa
2005 Newbold, J.D., S.A. Thomas, G.W. Minshall, C.E. Cushing, and T. Georgian. 2005. Deposition, benthic residence, and resuspension of fine organic particles in a mountain stream. Limnology and Oceanography. 50:1571-1580.Online
Brookshire, J.D., H. M. Valett, S. A. Thomas, and J.R. Webster. 2005. Cycling of dissolved organic nitrogen in a forested headwater stream. Ecology. 86:2487-2496.Online
Cross, W.F., J.P. Benstead, P.C. Frost, and S.A. Thomas. 2005. Applying principles of ecological stoichiometry to freshwater benthic ecology: recent progress and future potential. Freshwater Biology. 50:1985-1912.
Schade, J., J. Espeleta, C.A. Klausmeier, M.E. McGroddy, S.A. Thomas, and L. Zhang. 2005. A conceptual framework for ecosystem stoichiometry: balancing resource supply and demand. Oikos. 109:40-51.Online
Thomas S.A., T.V. Royer, E.B. Snyder, and J,C, Davis. 2005. Organic carbon spiraling in the Snake River, Idaho, USA. Aquatic Sciences. 67:424-433.
Mulholland, P.J., H.M. Valett, J.R. Webster, S.A. Thomas, L. Cooper, S. Hamilton and B.J. Peterson. 2004. Stream denitrification and total nitrate uptake rates measured using a field 15N isotope tracer approach. Limnology and Oceanography 49(3) 809-820.Online
Thomas, S.A. T.V. Royer, and G. W. Minshall. 2003. Assessing the Role of Marine Derived Nutrients in Idaho Streams. Nutrients in Salmonid Ecosystems; Sustaining Productivity and Biodiversity. American Fisheries Society, Syposium 34, 41-55.
Thomas, S.A., H.M. Valett, P.J. Mulholland, and J.R. Webster. 2003. A regression approach to estimating reactive solute uptake in advective and transient storage zones of stream ecosystems. Advances in Water Resources. 26: 965-976.Online
2001 Thomas, S.A., H.M. Valett, P.J. Mulholland, and J.R. Webster, C.S. Fellows, C.N. Dahm, and C.G. Peterson. 2001. Nitrogen retention in headwater streams: the influence of groundwater - surface water interaction. TheScientificWorld 1:623-631.
Thomas, S.A., J.D. Newbold, G.W. Minshall, T. Georgian, M.T. Monaghan, and C.E. Cushing. 2001. Transport and deposition of fine and very-fine organic particles in streams: implications for deposition mechanisms in turbulent environments. Limnology and Oce



DegreeMajorInstitutionYear Awarded
Doctorate of PhilosophyAquatic EcologyIdaho State University2000
Master of ScienceZoologyUniversity of Wyoming1991
Bachelor of ScienceBotanyUniversity of New Hampshire1987





TitleAwarded byYear Awarded
Recognition of Junior Faculty for Excellence in ResearchAgricultural Research Division of UNL2010




SNR Program Areas

  • Applied Ecology
  • Environmental Science

Areas of Interest/Expertise

  • Spatial dynamics of biogeochemical cycling in ecosystems
  • stream ecosystems
  • Population Dynamics, Distribution
  • River and Streams
  • Aquatic Ecosystems
  • Ecohydrology
  • Freshwater
  • Resilience
  • Watersheds
  • Insect Ecology


Currently this page only displays grants that were awarded on 1/1/ 2009 to the present. If a grant was awarded prior to 1/1/ 2009 and is still active, it will not be displayed on this page.

Grant TitleMTM 2: Discovering in reverse using isotopic translation of omics to reveal ecological interactions in microbiomes
Starting Date09/01/2021


Ending Date08/31/2026
Funding Level$267,094.00
Funding AgencyNorthern Arizonia University


Grant TitleStreamnet: Building Capacity to Improve Water Quality
Starting Date06/30/2020


Ending Date06/30/2021
Funding Level$307,730.00
Funding AgencyNebraska Evironmental Trust


Grant TitlePrairie Corridor Phase 3
Starting Date05/01/2019


Ending Date06/30/2020
Funding Level$58,544.00
Funding AgencyCity of Lincoln


Grant TitleUnderstanding the influence of land practices and canopy cover restoration on nutrient spiraling in tropical and temperate stream ecosystems
Starting Date07/01/2018


Ending Date08/01/2020
Funding Level$18,562.00
Funding AgencySPRINT - ARD/Global Engagement office


Grant TitleAnnual Meeting of the Society for Freshwater Science
Starting Date05/19/2018


Ending Date05/24/2018
Funding Level$500.00
Funding AgencyIANR Travel Fund


Grant TitleThe Effects of Alum and Fish Restoration on Water Quality in the Fremont Lake, NE (additional extension funding)
Starting Date05/01/2014


Ending Date06/30/2015
Funding Level$31,009.00
Funding AgencyNebraska Department of Environmental Quality


Grant TitleChlorophyll in Nebraska Lake Samples
Starting Date01/01/2014


Ending Date12/31/2015
Funding Level$4,050.00
Funding AgencyNebraska Department of Environmental Quality


Grant TitleRAPID: Using Drought-enhanced Nitrate Pulse to Understand Stream N Retention and Processing
Starting Date10/01/2012


Ending Date09/30/2013
Funding Level$198,949.00
Funding AgencyNational Science Foundation


Grant TitleUnderstanding Cyanobacteria Blooms in Willow Creek Reservoir
Starting Date08/01/2012


Ending Date07/31/2014
Funding Level$79,860.00
Funding AgencyLower Elkhorn NRD


Grant TitleDimensions: Stream Biodiversity: Supp. (additional funding)
Starting Date06/06/2012


Ending Date03/31/2016
Funding Level$20,582.00
Funding AgencyNational Science Foundation


Grant TitleFremont Water Quality (additional funding)
Starting Date04/13/2012


Ending Date06/30/2015
Funding Level$23,700.00
Funding AgencyNebraksa Department of Environmental Quality


Grant TitleFremont Water Quality
Starting Date04/06/2012


Ending Date06/30/2014
Funding Level$240,448.00
Funding AgencyNebraksa Department of Environmental Quality


Grant TitleChlorophyll in Nebraska Lake Samples
Starting Date03/01/2012


Ending Date12/31/2013
Funding Level$4,013.00
Funding AgencyNebraska Department of Environmental Quality


Grant TitleAn Integrative Traits-Based Approach to Predicting Variation in Vulnerability of Tropical and Temperate Stream Biodiversity to Climate Change (additional funding)
Starting Date04/01/2011


Ending Date03/31/2016
Funding Level$290,229.00
Funding AgencyNational Science Foundation


Grant TitleCyanobacteria Bloom
Starting Date03/01/2011


Ending Date02/28/2013
Funding Level$178,376.00
Funding AgencyNebraska Department of Environmental Quality


Grant TitleFIBR: Linking Genes to Ecosystems (additional funding)
Starting Date10/01/2010


Ending Date09/30/2011
Funding Level$10,000.00
Funding AgencyUniversity of California-Riverside


Grant TitleFIBR: Linking Genes to Ecosystems (additional funding)
Starting Date10/01/2010


Ending Date09/30/2011
Funding Level$81,018.00
Funding AgencyUniversity of California-Riverside


Grant TitleFIBR: Linking Genes to Ecosystems (additional funding)
Starting Date10/01/2009


Ending Date09/30/2010
Funding Level$126,570.00
Funding AgencyUniversity of California-Riverside



Graduate Programs

Master of Applied Science

Master of Science in Natural Resource Sciences
including specializations in

  • Applied Ecology
  • Hydrological Sciences

Doctorate of Philosophy in Natural Resource Sciences
including specializations in

  • Applied Ecology
  • Hydrological Sciences

Courses Taught

Course NumberCourse TitleFall Even YearsFall Odd YearsSpring Even YearsSpring Odd YearsSummer SessionCross Listing
NRES 281Introduction to Water ScienceXXGEOG/WATS 281
NRES 481/881Stream and River EcologyXXBIOS/WATS 481/881