Current Research

Biogeochemistry of boreal river networks

We are measuring the sources, transformations, and fluxes of dissolved organic matter and greenhouse gases in large boreal river networks, from soils to the sea. The Romaine River is in the process of being dammed for hydropower, so we will also have the opportunity to identify distinct contributions of river/reservoir sections at varying stages of pre- and post-dam to network- and landscape-scale biogeochemistry. With P del Giorgio (Université du Québec à Montréal), et al.

Controls on carbon fluxes in streams and rivers

We are quantifying external and in situ physical and biological controls on stream and river carbon fluxes. We are also developing models that identify the principal drivers of carbon fluxes and cycling in river networks. With J Karlsson, R Sponseller, J Klaminder, M Rosvall (Umeå University), H Laudon (Swedish University of Agricultural Sciences), et al.

Hotchkiss, E.R., R.O. Hall, R.A. Sponseller, D. Butman, J. Klaminder, H. Laudon, M. Rosvall, & J. Karlsson. 2015. Sources of and processes controlling CO2 emissions change with the size of streams and rivers. Nature Geoscience 8: 696-699.

Hotchkiss, E.R., R.M. Burrows, J. Klaminder, H. Laudon, R.A. Sponseller, & J. Karlsson. Integrating stream metabolism with carbon fluxes in a boreal river network. In Preparation.

Nutrient limitation in boreal streams

We are exploring interactions between nutrient and carbon availability, metabolism, and microbial assemblages in streams with varying water chemistry and landscape characteristics. With R Burrows (Griffith University), M Jonsson, R Sponseller (Umeå University), H Laudon, B Mckie (Swedish University of Agricultural Sciences).

Ecosystem production and environmental change

Multiple projects are using experimental ponds and whole-lake manipulations to identify how increases in temperature, nutrients and/or organic carbon alter productivity, food web dynamics, and carbon cycling. With J Karlsson, P Byström, M Klaus, M Jonsson (Umeå University), et al.

Hotchkiss, E.R., P. Byström, & J. Karlsson. Response of pond ecosystem metabolism to increasing water temperatures and terrestrial organic matter inputs. In Preparation. 

Sources, uptake, and fate of organic matter in freshwater ecosystems

I am interested in large-scale patterns of dissolved organic matter uptake and fate, how these may shift with environmental change, and the consequences for aquatic food webs. Collaborators from different working groups and workshops: WM Wollheim, MM Mineau (University of New Hampshire), JS Kominoski (Florida International University), RT Barnes (Colorado College), AJ Ulseth (University of Vienna), IF Creed (Western University), AK Bergström (Umeå University), et al.

Mineau, M.M., W.M. Wollheim, I.D. Buffam, S.E.G. Findlay, R.O. Hall, E.R. Hotchkiss, L.E. Koenig, W.H. McDowell, & T.B. Parr. Dissolved organic carbon uptake in streams: A review and assessment of reach-scale measurements. In Review.

Creed, I.F., A.K. Bergström, et al. Global change-driven effects on dissolved organic matter and implications for aquatic food webs. In Preparation.

Consequences of multiple species invasions in a productive spring stream

Four non-native fish species (convict cichlid, green swordtail, guppy, tadpole madtom) and one non-native snail species (red-rim melania) have established populations in Kelly Warm Springs, Grand Teton National Park, Wyoming. We are using historical samples to compare densities and biomass of native invertebrate species before and after the red-rim melania invasion. To quantify how multiple species invasions may influence stream food webs, we also measured fish and invertebrate population densities and biomass as well as fish stomach contents along a natural temperature gradient. With T Niekum, S Laske, R Hays, RO Hall (University of Wyoming).