Current Research

Biogeochemistry of boreal river networks

We are measuring the sources, transformations, and fluxes of dissolved organic matter and greenhouse gases in a large boreal river network, 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, M Gérardin (Université du Québec à Montréal), et al.

Hotchkiss, E.R. & P.A. del Giorgio. Carbon transport, losses, and replenishment in a boreal river discontinuum. In Preparation.

Metabolic controls on carbon emissions and export in running waters

We are quantifying the role of aquatic ecosystem metabolism in modifying stream network carbon fluxes in the boreal Krycklan Catchment. We are also using data and model simulations to identify the principal sources of carbon dioxide emissions from temperate, boreal, and arctic streams and rivers. 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 boreal 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

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

Klaus, M., S. MacIntyre, E.R. Hotchkiss, A.-K. Bergström, & J. Karlsson. Depth-integrated metabolism in clear and brown boreal lakes: the importance of accounting for vertical oxygen fluxes. In Preparation.

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

We are 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. Online Early. Dissolved organic carbon uptake in streams: A review and assessment of reach-scale measurements. Journal of Geophysical Research - Biogeosciences. DOI: 10.1002/2015JG003204.

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