I obtained my diploma (MSc) from Swiss Federal Institute of Technology Zürich (ETHZ) in 2003 under the guidance of PD Dr. Christopher Robinson (Swiss Federal Institute of Aquatic Science and Technology [EAWAG]) after which I worked in different academic jobs as a research and teaching assistant (ETHZ, EAWAG) until commencing my PhD studies at the University of Notre Dame, IN, USA, in 2006. After finishing with my Doctorate, I continued my research studies as a postdoctoral research associate at Kansas State University under the guidance of Professors Walter Dodds and Keith Gido and in collaboration with many others from different universities (eg, University of Georgia Athens, University of New Hampshire, University of Vermont, University of Alaska Fairbanks). At the end of 2014 I returned to Switzerland and started an independent research project funded by Swiss National Science Foundation’s Ambizione program, as an associated researcher in Prof. Tom Battin’s Stream Biofilm and Ecosystem Science group at Swiss Federal Institute of Technology Lausanne. From 2019 – 2021, I was a postdoctoral researcher at the University of Lausanne jointly at the Institute of Earth Surface Dynamics and the Interdisciplinary Centre for Mountain Research, studying the freshwater continuum, meaning the link between flowing and standing waters, in collaboration with Professors Marie-Elodie Perga and Stuart Lane. Since 2022, I am an academic staff member of the Department of Aquatic Ecology at the BTU.

Spatio-temporal dynamics of stream macroinvertebrates and stream metabolism in lowland sandy-bottom streams

This research topic is based on two interests. Firstly, lowland sandy-bottom streams are still underrepresented in our knowledge about stream ecosystems, though they are a prevalent stream type in Brandenburg. Generally, habitat types are identified by sediment size, but in sandy-bottom stream, all inorganic sediment is of a similar size. At the same time, the small grain size of sand means it can be easily moved by stream flow, creating areas of moving sand, called ripples, and areas of deposition, which often also accumulates fine organic matter. Understanding how macroinvertebrates use the different habitat types, and the metabolic function of these habitats, will inform restoration efforts both in terms of reference conditions and restoration objectives.

Secondly, winters are still underrepresented in stream ecological studies, though recent research has shown that macroinvertebrate production and metabolic activity can be quite high in winter. Understanding the temporal patterns can identify critical times where management may need to be adjusted, to allow for queues (e.g., higher flows).

Aquatic metabolism along a lake chain: linking lotic and lentic metabolism

Freshwaters are generally separated into lotic (i.e., flowing water, e.g., streams) and lentic (i.e., still water; e.g., lakes) ecosystems, both of which have been proposed as sentinels of environmental change. Despite the clear connection between the two aquatic ecosystems, as lakes are generally fed by tributary streams and lakes alter the conditions of the stream along its continuum, the study of lakes and streams is rarely combined. Direct study of lentic-lotic linkages, both in terms of the transition zones and the freshwater continuum (i.e., stream-lake-stream interactions) is needed to better understand the freshwater aquatic ecosystem. In fact, water resource management and protection of aquatic ecosystems is mostly based on river basins that include various freshwater bodies, be they streams, rivers, or lakes, and requires thinking about freshwater ecosystems at a more integrated level, including the consideration of physical, chemical and biological properties.

Recent advances in sensor technology and computing power have allowed for the measurement of dissolved oxygen series and their modeling to estimate ecosystem metabolic rates in a diversity of ecosystems. Standing (i.e., lentic) and running (i.e., lotic) waters differ in their aquatic communities due to the different physiological adaptations needed to survive. For example, macroinvertebrates in standing waters need to potentially withstand lower oxygen conditions due to limitations in supply, while oxygen is generally more abundance in flowing water, but organisms have to protect themselves from being carried away by flow. Metabolic rates offer a metric applicable across ecosystem boundaries, but research has yet to link the metabolic rates of an inflowing stream to those of the receiving lake, of that of the lake to the outflowing stream. Streams and lakes are inherently connected, but that is not yet reflected in the research on freshwater ecosystems.

Ecosystem metabolism as an indicator of food web dynamics

Measuring food web dynamics is incredibly time consuming and requires a great deal of expertise. Thus, scientists and managers are considering using metabolic rates as an assessment of ecological health. However, currently it is not known, how metabolic rates relate to food web dynamics. For example, is the measurement of gross primary production related to the biomass of producers found in an ecosystem? Can ecosystem respiration approximate the production of fish within an aquatic ecosystem? These and many other questions need to be answered before metabolic rates can be effectively used as an assessment tool.

To determine the linkage between organismal dynamics, joint measurements of organisms such as macroinvertebrates and ecosystem metabolism such as sediment production and respiration are needed. These measurements need to be replicated in time to allow the calculation of organismal production, also termed secondary production, and to establish the spatio-temporal dynamics of metabolic rates. In addition, the physical, chemical and biological environmental parameters need to be measured to establish drivers of both organismal and metabolic dynamics. Only the holistic view will allow for the comprehension of aquatic ecosystem an how one metric may be used as a proxy for another.

Peer-reviewed

35. Perga, M. E., C. Minaudo, T. Doda, F. Arthaud, H. Beria, H.E. Chmiel, N. Escoffier, T. Lambert, R. Napolleoni, B. Obrador, P. Perolo, J. Rüegg, H. Ulloa, and D. Bouffard. 2023. Near‐bed stratification controls bottom hypoxia in ice‐covered alpine lakes. Limnology and Oceanography, accepted.

34. Escoffier, N., P. Perolo, T. Lambert, J. Rüegg, D. Odermatt, T. Adatte, T. Vennemann, and M.E. Perga. 2022. Controls on whiting event triggering at the interface between Lake Geneva and the Rhône River. Journal of Geophysical Research: Biogeoscience127: e2022JG006823

33. Ruffing, C.M., A.M. Veach, A. Schechner, J. Rüegg, M.T. Trentman, and W.K. Dodds. 2022. Prairie stream metabolism recovery varies based on network position and antecedent hydrology after a bank-full flood. Limnology and Oceanography 67: 1986-1999.

32. Rüegg, J., C. Moos, A. Gentile, G. Luisier, A. Elsig, G. Prasicek, and I. Otero. 2022. Investigating the concept of mountain forest protection and management as a means for flood protection. Frontiers in Forests and Global Change 138.

31. Otero, I., F. Darbellay, E. Reynard, M.E. Perga, G. Prasicek, M. Cracco, G. Hetényi, M. de Vaan, J. Rüegg, C. Clivaz, J. Garcìa, A. Guisan, C. Moos, B. Schaeffli, and J. Bussard. 2021. Designing interdisciplinary research on mountains. What place for the unexpected? Mountain Research and Development 40.

30. Rüegg, J., C.C. Conn, E.P. Anderson, T.J. Battin, E.S. Bernhardt, M. Boix Canadell, S.M. Bonjour, J.D. Hosen, N.S. Marzolf, and C.B. Yackulic. 2021. Thinking like a consumer: linking aquatic basal metabolism and consumer dynamics. Limnology & Oceanography Letters 6:1-17.

29. Currier, C.M., D.T. Chaloner, J. Rüegg, S.D. Tiegs, D. D’Amore, and G.A. Lamberti. 2020. Beyond nitrogen and phosphorus subsidies: The potential of Pacific salmon (Oncorhynchus spp.) as vectors of micronutrients. Aquatic Sciences 82: 1-11.

28. Rüegg, J., D.T. Chaloner, F. Ballantyne, P.S. Levi, C. Song, J.L. Tank, S.D. Tiegs, and G.A. Lamberti 2020. Understanding the relative roles of salmon spawner enrichment and disturbance: a high-frequency, multi-habitat field data and modeling approach. Frontiers in Ecology and Evolution 8, 19.

27. Trentman, M.T., W.K. Dodds, K.B. Gido, J. Rüegg, and C.M. Ruffing. 2020. Using path analysis to determine interacting effects of biotic and abiotic factors on patch-scale biogeochemical rates in a prairie stream. Aquatic Sciences 82, 26.

26. Song, C., W.K. Dodds, J. Rüegg, A. Argerich, C.L. Baker, W.B. Bowden, M.M. Douglas, K.J. Farrell, M.B. Flinn, E.A. Garcia, A.M. Helton, T.K. Harms, S. Jia, J.B. Jones, L.E. Koenig, J.S. Kominoski, W.H. McDowell, D. McMaster, S.P. Parker, A.D. Rosemond, C.M. Ruffing, K.R. Sheehan, M.T. Trentman, M.R. Whiles, W.M. Wollheim, and F. Ballantyne IV. 2018. Warming induces asymmetric convergence of stream metabolic balance. Nature Geosciences 11: 415–420.

25. Farrell, K.J., A.D. Rosemond, J.S. Kominoski. S.M. Bonjour, J. Rüegg, L.E. Koenig, C.L. Baker, M.T. Trentman, T.K. Harms, and W.H. McDowell. 2018. Variation in detrital resource stoichiometry signals differential carbon to nutrient limitation for stream consumers across biomes. Ecosystems 21, 1676–1691.

24. Koenig, L.E., C. Song, W.M. Wollheim, J. Rüegg, and W.H. McDowell. 2017. Nitrification increases nitrogen export from a tropical river network. Freshwater Science 36: 698-712.

23. Siders, A.C., D.M. Larson, J. Rüegg, and W.K. Dodds. 2017. Probing whole-stream metabolism: influence of spatial heterogeneity on rate estimates. Freshwater Biology 62: 711-723.

22. Song, C., W.K. Dodds, M.T. Trentman, J. Rüegg, and F. Ballantyne IV. 2016. Methods of approximation influences stream metabolism estimates. Limnology and Oceanography: Methods 14: 557-567.

21. Rüegg, J., W.K. Dodds, M.D. Daniels, K.R. Sheehan, C.L. Baker, W.B. Bowden, K.J. Farrell, M.B. Flinn, T.K. Harms, J.B. Jones, L.E. Koenig, J.S. Kominoski, W.H. McDowell, S.P. Parker, A.D. Rosemond, M.T. Trentman, M.R. Whiles and W.M. Wollheim. 2016. Multi-scale comparison of geomorphic heterogeneity in stream networks across diverse biomes. Landscape Ecology 31: 119-136.

20. Rüegg, J., J.J. Eichmiller, N. Mladenov and W.K. Dodds. 2015. Dissolved organic carbon concentration and flux in prairie streams: spatial and temporal patterns and processes from long-term data. Biogeochemistry 125: 393-408.

19. Rüegg, J., Brant, D. Larson, M. Trentman and W.K. Dodds. 2015. A portable, modular, self-contained recirculating chamber to measure benthic processes under controlled water velocity. Freshwater Science 34: 831-844.

18. Trentman, M.T, W.K. Dodds, J.S. Fencl, K. Gerber, J. Guarneri, S. Hitchman, Z. Peterson and J. Rüegg. 2015. Quantifying ambient nutrient uptake and functional relationships of uptake versus concentration in streams: a comparison of stable isotope, pulse, and plateau approaches. Biogeochemistry 125: 65-79.

17. Bobeldyk, A.M., J. Rüegg and G.A. Lamberti. 2015. Freshwater hotspots of biological invasion are a function of species-pathway interactions. Hydrobiologia 746:363-373.

16. Rüegg, J., C. Gries, B. Bond-Lamberty, G.J. Bowen, B.S. Felzer, N.E. McIntyre, P.A. Soranno, K.L. Vanderbilt, and K.C. Weathers. 2014. Completing the data life cycle: using information management in macrosystems ecology research. Frontiers in Ecology and the Environment 12:24-30.

15. Goring, S.J., K.C. Weathers, W.K. Dodds, P.A. Soranno, L.C. Sweet, K.S. Cheruvelil, J.S. Kominoski, J. Rüegg, A.M. Thirn and R.M. Utz. 2014. Improving the culture of interdisciplinary collaboration in ecology by expanding measures of success. Frontiers in Ecology and the Environment 12:39-47.

14. Rüegg, J., D.T. Chaloner, S.D. Tiegs and G.A. Lamberti. 2014. Habitat influences Pacific salmon (Oncorhynchus spp.) tissue decomposition in riparian and stream ecosystems. Aquatic Sciences 76:623-632.

13. Levi, P.S., J.L. Tank, J. Rüegg, D.J. Janetski, S.D. Tiegs, D.T. Chaloner and G.A. Lamberti. 2013. Whole-stream metabolism responds to spawning Pacific salmon in their native and introduced ranges. Ecosystems 16:269-283.

12. Reisinger, A.J., D.T. Chaloner, J. Rüegg, S.D. Tiegs and G.A. Lamberti. 2013. The effect of migrating salmon on the isotopic composition of biota differs among Southeast Alaska streams. Freshwater Biology 58:938-950.

11. Langhans, S.D., U. Richard, J. Rüegg, U. Uehlinger, P. Edwards, M. Doering and K. Tockner. 2013. Environmental heterogeneity affects input, storage, and transformation of course particulate organic matter in a floodplain mosaic. Aquatic Sciences 75:335-348.

10. Levi, P.S., J.L. Tank, S.D. Tiegs, J. Rüegg, D.T. Chaloner and G.A. Lamberti. 2012. Does timber harvest influence the dynamics of marine-derived nutrients in Southeast Alaska streams? A reply to C.R. Jackson and D.J. Martin. Canadian Journal of Fisheries and Aquatic Sciences 69:1898-1901.

9. Choate, D.M., C.M. Prather, M.J. Michel, A.K. Baldridge, M.A. Barnes, D. Hoekman, C.J. Patrick, J. Rüegg and T.A. Crowl. 2012. Integrating theoretical components: a graphical model for graduate students and researchers. BioScience 62:594-602.

8. Rüegg, J., D.T. Chaloner, P.S. Levi, J.L. Tank, S.D. Tiegs and G.A. Lamberti. 2012. Environmental variability and the ecological effects of spawning Pacific salmon on stream biofilm. Freshwater Biology 57:129-142.

7. Levi, P.S., J.L. Tank, S.D. Tiegs, J. Rüegg, D.T. Chaloner and G.A. Lamberti. 2011. Does timber harvest influence the dynamics of marine-derived nutrients in southeast Alaska streams? Canadian Journal of Fisheries and Aquatic Sciences 68:1316-1329.

6. Tiegs, S.D., P.S. Levi, J. Rüegg, D.T. Chaloner, J.L. Tank and G.A. Lamberti. 2011. Ecological effects of live salmon exceed those of carcasses during an annual spawning migration. Ecosystems 14:598-614.

5. Rüegg, J., S.D. Tiegs, D.T. Chaloner, P.S. Levi, J.L. Tank and G.A. Lamberti. 2011. Salmon subsidies alleviate nutrient limitation of benthic biofilms in southeast Alaska streams. Canadian Journal of Fisheries and Aquatic Sciences 68:277-287.

4. D’Amore, D.V., N.S. Bonzey, J. Berkowitz, J. Rüegg and S. Bridgham. 2011. Holocene soil-geomorphic surfaces influence the role of salmon-derived nutrients in the coastal temperate rainforest of Southeast Alaska. Geomorphology 126:377-386.

3. Tiegs, S.D., E.Y. Campbell, P.S. Levi, J. Rüegg, M.E. Benbow, D.T. Chaloner, R.W. Merritt, J.L. Tank and G.A. Lamberti. 2009. Separating physical disturbance and nutrient enrichment caused by Pacific salmon in stream ecosystems. Freshwater Biology 54:1864-1875.

2. Tiegs, S.D., D.T. Chaloner, P. Levi, J. Rüegg, J.L. Tank and G.A. Lamberti. 2008. Timber harvest transforms ecological roles of salmon in Southeast Alaska rain forest streams. Ecological Applications 18:4-11.

1. Rüegg, J., and C. T. Robinson. 2004. Comparison of macroinvertebrate assemblages of permanent and temporary streams in an Alpine floodplain, Switzerland. Archiv für Hydrobiologie 161: 489–510.

Doctoral thesis

Rüegg, J. 2011. Responses of stream biofilm to Pacific salmon (Oncorhynchus spp.) spawners: The role of environmental context and scale. Doctoral thesis, University of Notre Dame, 206 pp.

Technical reports

Rüegg, J. 2003. Macun Monitoring Manual. Swiss National Park Research, A commission of the Swiss Academy of Sciences.