Past Research

Tracing carbon sources in boreal stream food webs

Large subsidies of terrestrial organic matter may support heterotrophic carbon (C) and nutrient demands in boreal streams, but the degree to which in-stream photosynthesis contributes to food web dynamics is not well known. We used stable isotopes to measure the contributions of terrestrial and aquatic C to invertebrate consumers. We also linked diet sources with ecosystem C pools and fluxes, including rates of whole-stream metabolism. With E Landström, R Sponseller, J Karlsson (Umeå University).


Landström, E., E.R. Hotchkiss, R.A. Sponseller, & J. Karlsson. High autochthonous support of boreal stream macroinvertebrates despite low rates of gross primary production. In Preparation.




Fate of newly fixed carbon in a mountain stream (NSF DDIG)


We traced the fate of newly fixed C using a whole-stream C stable isotope addition. We modeled short-term rates of algal dissolved organic C and
CO2 production. We also measured longer-term residence time of newly fixed C. 


Hall, R.O., J.L. Tank, M.A. Baker, E.J. Rosi-Marshall, E.R. Hotchkiss. In Press. Metabolism, gas exchange, and carbon spiraling in rivers. Ecosystems.






Microbial assemblage structure and freshwater carbon cycling

We used microbial genomic data and measurements of microbial carbon consumption from different freshwater ecosystems to test how microbes may respond to changes in carbon and nutrient sources.

Hotchkiss, E.R., N.C. Berg-Mattson, S.A. Gregory, A.L. Saville, & R.O. Hall. Microbial assemblage structure and carbon source control dissolved organic carbon consumption. In Preparation.







Diel ecosystem respiration in streams

We used diel changes in 18:16
O2, linked with Bayesian inverse modeling, to estimate diel changes in ER in three Wyoming streams.








Controls on nitrate uptake in a semi-arid stream 

We quantified the role of hydrology, geomorphology, and biology in governing water chemistry and nitrate uptake along three different reaches of Red Canyon Creek, WY.

Hubbard, K.A., L.K. Lautz, M.J. Mitchell, B. Mayer, & E.R. Hotchkiss. 2010. Evaluating nitrate uptake in a Rocky Mountain stream using labelled 15N and ambient nitrate chemistry. Hydrological Processes 24: 3322-3336.








CO2 production by invasive snail calcification

We measured rates of biomass and CO2 production during growth and calcification by the invasive freshwater snail, Melanoides tuberculata, in Kelly Warm Springs, WY. We compared Melanoides CO2 and secondary production with ecosystem metabolism and fluxes of CO2 from the stream to the atmosphere.

Hotchkiss, E.R., & R.O. Hall. 2010. Linking calcification by exotic snails to stream inorganic carbon cycling. Oecologia 163: 235-245.






Denitrification in a tropical stream 

The loss of fish species may alter stream nitrogen (N) budgets. Land use changes and increased sedimentation also alter benthic substrate and N availability, and both are important factors in denitrification. We quantified denitrification in Rio Las Marías, Venezuela and compared denitrification to other rates of ecosystem N loss and cycling.

Solomon, C.T., E.R. Hotchkiss, J.M. Moslemi, A.J. Ulseth, E.H. Stanley, R.O. Hall, & A.S. Flecker. 2009. Sediment size and nutrients regulate denitrification in a tropical stream. Journal of the North American Benthological Society 28: 480-490.






Land use and stream nitrogen cycling

I was a graduate assistant for the last season of LINX2 research on nitrogen (N) transport and uptake in streams using 15N tracer additions in urban, agricultural, and reference streams in and around Grand Teton National Park, WY.

Lotic Intersite Nutrient eXperiments (LINX)








Sea turtle population dynamics

I collected data on reproductive females, nesting activities, and hatch success of hawksbill, leatherback, and green sea turtles on Buck Island Reef National Monument. I also helped with exotic mammal removal and monitoring, in-water juvenile hawksbill mark and recapture, and the creation of a plant ID database for Buck Island, St. Croix, U.S. Virgin Islands.


Productivity of restored and managed wetlands

I assisted with a project studying the density, diversity and productivity of aquatic plants and macroinvertebrates in a restored wetland, and their impact on waterfowl feeding behavior in Two Rivers National Wildlife Refuge, IL. 

Two Rivers National Wildlife Refuge







Conjunctivitis and house finch behavior

My undergraduate research project quantified changes in house finch feeding behavior and aggression when infected with Microplasma gallisepticum.

Hotchkiss, E.R., A.K. Davis, J.J. Cherry, & S. Altizer. 2005. Mycoplasmal conjunctivitis and the behavior of wild house finches (Carpodacus mexicanus) at bird feeders. Bird Behavior 17: 1-8.









Nutrient limitation in a tropical stream (OTS REU

I studied the role of limiting nutrients on chironomid larvae growth rates in the laboratory 
at La Selva Biological Station, Costa Rica. I also helped with a project measuring nutrient limitation of in-stream microbial respiration.


Nitrogen cycling in streams and reservoirs

My independent project compared potential rates of nitrification and denitrification in streams surrounded by different land-use types (forested, urban, and agricultural). I also assisted with field and laboratory work for several projects studying the nitrogen dynamics in Michigan streams and a reservoir in Illinois.

Tank Research Group







Genetic diversity of spatially isolated switchgrass

I quantified the genetic diversity of spatially isolated switchgrass populations from the eastern United States.

Plant Systems Biology