Time: Tuesday, 17/June/2025: 2:30pm - 3:20pm Session Chair: Loïc N Michel Session Chair: Nemiah Ladd |
Location: 5161.0151 Bernoulliborg, Nijenborgh 9, 9747 AG Groningen |
Keynote: Using stable isotopes as tools to solve the Rumsfeld matrix in ecology
University of Glasgow, United Kingdom
Although not the original thinker behind the philosophical approach, US hawk Donald Rumsfeld famously categorised information into “known knowns, known unknowns, unknown knowns, and unknown unknowns”.
Although his comments were treated with disdain at the time, after 20 years I have come to grudgingly accept that this way of thinking parallels the experience of many environmental scientists, for example those working on problems of the function, evolution and conservation of the natural resources on which we rely on as humans. In this talk, I will introduce a series of field-based studies where stable isotopes have proven to be fundamental in helping us to identify and examine some known knowns, known unknowns, unknown knowns, and unknown unknowns in aquatic ecology.
Using compound-specific stable isotope analysis to trace essential fatty acid bioconversion in invertebrates and fish
1Wasser Cluster Lunz, Austria; 2Universität for Continuing Education Krems, Research lab of Aquatic Ecosystem Research and -Health, Dr. Karl-Dorrek-Straße 30, 3500 Krems, Austria; 3University of Jyväskylä, Department of Biological and Environmental Science, Survontie 9C, 40014, Jyväskylä, Finland; 4University of Cologne, Institute for Zoology, Zülpicher Straße 47b, D-50674, Köln, Germany; 5University of Southern Bohemia, Na Sádkách 7, 370 05 České Budějovice, Czech Republic; 6University of Eastern Finland, Department of Environmental and Biological Sciences, Yliopistokatu 2, 80100 Joensuu, Finland; 7University of Ottawa, National Facility in Accelerator Mass Spectrometry Laboratory, 25 rue Templeton Street (ARC411), Ottawa, ON, K1N6N5
Survival, growth, and reproduction of consumers depend on the acquisition of sufficient dietary energy and essential micronutrients. Organisms at the base of the aquatic food web synthesize essential polyunsaturated fatty acids (PUFA), which are transferred to consumers at higher trophic levels. Many consumers, requiring omega-3 long-chain (n-3 LC)-PUFA such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have limited ability to biosynthesize them from the essential dietary precursor α-linolenic acid (ALA) and thus rely on dietary provision of LC-PUFA. If the dietary supply of such PUFA does not match the physiological needs, consumers may need to bioconvert dietary precursors into the required molecules. Such conversion may provide an ecological disadvantage over consumers that have direct access to required dietary compounds. We present a method, based on compound-specific stable hydrogen isotopes, to elucidate metabolic processing of fatty acids in both laboratory and field experiments. We show how compound-specific stable hydrogen isotopes of fatty acids can be used to study dietary limitations and bioconversion of n-3 PUFA in zooplankton and in fish. Furthermore, it can be used to discriminate between PUFA regulators and PUFA accumulators in ecosystems, whose functional diversity can have substantial impact on the availability of PUFA to higher trophic levels and thus influence ecosystem resilience.