Ryan Sponseller

Climate change induced regime shifts in Northern lake ecosystems

Sunset over lake Törnetrask (as seen from the Abisko Scientific Research Station)

Sunset over lake Törnetrask (as seen from the Abisko Scientific Research Station)

Climate change induced regime shifts in Northern lake ecosystems

Project Summary

A present major scientific challenge is to understand and predict effects of climate change on lake ecosystems and the services they deliver. Globally, lakes are concentrated at northern latitudes where the magnitude of climate change is expected to be strongest. Recent advances in lake research suggest that responses of Northern lakes to global warming are fundamentally different from the expectations based on conventional knowledge. This project brings together new tools and concepts in biogeochemistry and ecology, with the aims of understanding and predicting the effects of climate change on the delivery of two major ecosystem services, fish production and the net greenhouse gas balance of Northern lakes.

Specific objectives include:

  1. Assessment of long vs. short term effects of climate change;
  2. Assessment of nonlinear dynamics and regime shifts; and,
  3. Projection of responses to future climate conditions.

The project’s core is made up of a multi-scale (pond to whole-lake) experimental test of ecosystem responses to increases in temperature and precipitation/runoff. Further, we will use aDNA techniques to address past regime shifts and ecosystem resilience to climate change from paleolimnological sediment records. Finally, the project will develop process-based models to be used in the projection of future conditions in lakes at the whole ecosystem scale.

Project Dates: 2017-2021

Funding Organizations

Knut and Alice Wallenberg Foundation

Collaborators

David Bastviken, Linköping University
Ann-Kristin Bergström, Umeå University
Christian Bigler, Umeå University
Richard Bindler, Umeå University
Åke Brännström, Umeå University
Pär Byström, Umeå University
Sebastian Diehl, Umeå University
Isabelle Domaizon, French National Institute for Agricultural Research
Göran Englund, Umeå University
Cristian Gudasz, Umeå University
Dag Hessen, Oslo University, Norway
Jonatan Klaminder, Umeå University
Sally MacIntyre, University of California Santa Barbara, USA
Frank Peeters, University of Konstanz, Germany
André de Roos, University of Amsterdam, The Netherlands
Martin Rosvall, Umeå University
David Seekell, Umeå University
Ryan Sponseller, Umeå University
Xiau-Ru Wang, Umeå University
Marcus Klaus, Umeå University

Taking the pulse of Swedish rivers: using metabolism to monitor ecosystem responses to environmental change

Taking the pulse of Swedish rivers: using metabolism to monitor ecosystem responses to environmental change

Project Summary

Streams and rivers carry out multiple ecosystem services that respond to and integrate natural and anthropogenic perturbations across landscapes. In northern regions, a critical aspect of this ‘integration’ involves the regulation of carbon (C) transfer from land to the atmosphere and sea. In this context, the degree to which streams and rivers transform terrestrial organic carbon (OC) and act as sources of CO2 to the atmosphere is subject to much current debate. National monitoring programs have the potential to shed light on this issue, yet these efforts rarely assess aquatic ecosystem processes. As a solution, we propose adding high frequency measurements of dissolved oxygen (DO) to current monitoring programs, which allow for the calculation of fundamental metabolic rates at daily time scales. Such measures reveal the ‘pulse’ of biological activity in running waters with the temporal resolution needed to capture changes in the degradation of terrestrial OC and CO2 production and fixation in response to diverse environmental changes. The goals of this research are to 1) determine how the rates and patterns of metabolism in Swedish rivers are shaped by regional climatic gradients and anthropogenic stressors, 2) Quantify the extent to which streams and rivers in arctic, boreal, and hemi-boreal zones degrade terrestrial OC, and contribute to CO2 evasion, and 3) Advance a simple and cost efficient method to assess metabolism that will complement current monitoring programs in Sweden by adding functional metrics

Funding Organization

Formas

Collaborators

Jan Karlsson, Umeå University
Erin Hotchkiss, Virginia Polytechnic Institute
Hjalmar Laudon, Swedish University of Agricultural Sciences, Umeå

The invisible carbon: an early indication of ecosystem change!

The invisible carbon: an early indication of ecosystem change!

Project Summary

Streams are sensitive sentinels for environmental change by their integration of processes in terrestrial and aquatic systems. Upland headwater streams in the north Swedish tundra show seasonally exceptional high concentrations of uncolored dissolved organic carbon (DOC) and high CO2 concentrations. We suggest that this reflects on-going changes in the terrestrial environment responding in their delivery of carbon (C) to the recipient aquatic systems. This is a hitherto unknown effect of a changing tundra landscape that will have large implications for the positive feedback on the global climate warming because of the large quantities of C that is stored in tundra soils. Current climate change mobilizes the stored C in upland tundra soils and cause a substantial increase in headwater stream C emissions and water-borne C losses.

We are studying stream CO2 fluxes mainly across a 42-km long stream network in the Miellajokka catchment near Abisko to better understand how stream functional traits and landscape features affects CO2 emissions. We are amongst others using different isotopic approaches (13C, 15N, 87Sr/86/Sr, 34S18O4 and water isotopes) and high-resolution measurements of stream CO2 and oxygen to disentangle different sources and processes that affects stream CO2 concentrations and emissions. We are also studying spatiotemporal variations in stream DOC across different tundra streams to unravel how different landscape features and hydrological conditions affect stream DOC concentrations, its degradability and qualitative characteristics. We are particularly interested in pulses of high stream DOC concentrations that has occurred irregularly during early autumns.

Collaborators

Carl-Magnus Mörth, Stockholm University
Steve Lyon, Stockholm University
Ann-Kristin Bergström, Umeå University
Ryan Sponseller, Umeå University
Jan Karlsson, Umeå University
Martin Berggren, Lund University
Gerard Rocher Ros, Umeå University

Funding organizations

The Swedish Research Council (VR) 2013-5001
FORMAS 2014-970