Janine Rüegg

Première assistante (FGSE – Centre interdisciplinaire de recherche sur la montagne)

Lauréate du subside Tremplin 2019

« Freshwater ecosystems, such as streams and lakes, are often inherently linked by the flow of water, but due to ecosystem and disciplinary boundaries they are rarely studied jointly nor viewed as part of a continuum. »

In a nutshell, what does your research at UNIL consist of?

I use a holistic approach of studying physical, chemical and biological aspects and further combine disparate research fields such as organismal and ecosystem science to study the freshwater continuum, meaning to also combine the study of lakes and streams as they are interconnected but rarely studied together. I studied the lotic-lentic (i.e., lotic=flowing to lentic=standing water) transition zones of Lac Derborence, where two stream, the Chevilleince and the Derbonne, enter the lake at opposite sides. As many ecosystem components may respond differently to environmental conditions, I studied not only the physio-chemical characteristics but also organisms, both in terms of structure and function. The main objectives of the research conducted already revolve around the questions of whether, and how, physical, chemical, and biological processes vary along the littoral zone in relation to the location of direct stream-lake water mixing.

For a larger scale view of the stream-lake-stream continuum, I currently have automated sensors deployed in the two inflowing streams, the lake and two locations in the outflowing stream (one just below the outflow and one further downstream). These sensors will allow me to determine the water budget, including how much water is delivered by the streams, the lake volume, the water flowing out of the lake and thus the time the water remains in the lake. I will then try to link these flow dynamics to the biological function of metabolism, meaning the production and respiration of organic matter in the in- and outflowing streams as well as the lake. Describing the interaction between temporal flow and metabolism patterns will provide a first step toward our understanding of the lotic-lentic-lentic continuum.

What do you plan to achieve during the « Tremplin » grant period?

During my Tremplin subsidy period I plan to author a manuscript detailing the conceptual framework of the freshwater continuum, followed by the presentation and subsequent publication of the findings on the physical, chemical, and biological patterns of the two studied transition zones. Summer field research will be focus on collecting data for sensor measurement conversions (e.g., depth measurements to discharge). During this time when I can focus on writing, the student(s) assistant(s) supported by the Tremplin subsidy will process the organismal samples collected, which I then plan to analyze and then publish within a few months after the end of the Tremplin subsidy period.