Key speakers
The research of Martin Kainz focuses on the importance of energy linkages among habitats in freshwater ecosystems. He is especially interested in the function of dietary energy from terrestrial and aquatic sources to consumers in aquatic food webs. He is currently interested in understanding how climate change affects functions, such as vision, cognition, and reproduction in aquatic consumers. His research team explores food web functioning using experimental and field studies and applies biochemical tracers, such as fatty acids and stable isotopes, and recently compound-specific stable isotopes. Martin's passion for exploring aquatic food webs has taken him to Canada, USA, China, Australia, and many countries in Europe. After his MSc at the University of Vienna, Martin Kainz pursued his doctoral research on trophic transfer of mercury in lakes and reservoirs of Québec, Canada, at the Université du Québec à Montréal, Canada. During this post-doctoral research at the University of Victoria, BC, and the Canadian Water Research Institute, Burlington, ON, Canada, he investigated how to use fatty acids as dietary biomarkers from various sources to aquatic consumers. He currently heads the research group LIPTOX at the Inter-university Centre for Aquatic Ecosystem Research 'WasserCluster Lunz' in Austria. Martin Kainz is currently also president of the Austrian Society of Limnology and a vice-president of the International Society of Limnology (SIL).
My lab page: www.kainzlab.com
THE MANY SECRETS OF AQUATIC FOOD WEBS - ESSENTIAL NUTRIENTS AND POTENTIAL CONTAMINANTS IN A CHANGING WORLD
Martin J. Kainz1, Matthias Pilecky, Libor Zavorka, Margaux Mathieu-Resuge, Fen Guo1, Nadine Ebm1, Sami Taipale2, Michael T. Brett3, Stuart E. Bunn4, Brian Fry4
1WasserCluster Lunz – Biologische Station (www.wcl.ac.at), Lunz am See, Austria martin.kainz@donau-uni.ac.at,
2Univeristy of Jyväskylä, Finland
3University of Washington, Seattle, Washington, USA
4Australian Rivers Institute, Griffith University, Brisbane, Australia
Dietary energy is essential for all consumers, whereas potential contaminants, such as microplastics (MP), may have detrimental physiological effects. In this talk, I will present current and upcoming research about dietary energy and contaminant sources and their physiological implications for aquatic consumers, and will focus on dietary carbon, lipids, and microplastics in organisms of various ecosystems. Among dietary energy sources, lipids and some polyunsaturated fatty acids (PUFA) are considered essential for consumers, yet in certain aquatic ecosystems their dietary provision may be too low to meet the consumers' physiological demand. I will present how consumers within various trophic networks utilize and rework lipids of allochthonous and autochthonous sources to meet their physiological requirements and how MP can become integral parts of cell membranes. In our current research program, we investigate fatty acids and compound-specific stable isotopes in leaf litter, algae, invertebrates, as well as in fish muscle tissues and organs (liver, gonads, brain, eyes) and show that consumers retain dietary energy preferably from autochthonous sources (algae), whereas long-chain saturated fatty acids, used as indicators of allochthonous dietary diet sources, decrease in concentrations with increasing trophic levels and remain isotopically unchanged. The combined use of fatty acids and their stable isotopes revealed that fishes can convert dietary PUFA to the highly unsaturated docosahexaenoic acid (DHA) in their liver cells and, based on lighter del13C values of DHA in fish brain and eyes than in fish liver, it is suggested that neural tissues can further synthesize essential DHA from precursor PUFA. In general, the supply of dietary energy appears to get steadily reworked within consumers of aquatic food webs and even in fish organs to satisfy the consumers' physiological demands. This presentation will round up with some perspectives for nutritional aquatic ecology in a world that faces unprecedented challenges during ongoing climate change.
