300519 SE Trophic Biomarkers in Aquatic Ecology and Ecotoxicology (2021W)

The provision of dietary energy, in particular during times of climate change, is important for survival strategies of all organisms. The aim of this course is to learn about mechanisms that drive sources, trophic transfer, and function of dietary organic matter through aquatic food webs. This course targets students with a strong background in ecology and/or with sufficient background in biochemistry as both groups will greatly benefit from learning how to address conceptual food web questions using modern biochemical methods, including stable isotopes, fatty acids, compound-specific stable isotopes, etc. First, students will learn about concepts of trophic ecology and energy pathways (units 1-5), then we will learn about the complexity of dietary pathways to organism at various trophic levels, including transfer, metabolism, and accumulation of physiologically essential (e.g., trace elements and essential fatty acids), and potentially toxic (e.g., persistent organic pollutants and heavy metals) diet. In particular, students will be introduced to new and upcoming dietary biomarkers (unit 6-8): A) stable isotopes and lipids/fatty acids (unit 6-7) in terrestrial and autochthonous (aquatic) organic matter are used to indicate dietary sources of carbon (d15C), nitrogen (d15N), and hydrogen (d2H) as markers of trophic relationships among organism within aquatic food webs. Moreover, stable isotopes (d13C and d2H) in fatty acids (unit 7) are one of the most upcoming methods to assess the flow and action of dietary energy in consumers and their organs. Depending on the biochemical stability of contaminants, the concurrent investigation of diet biomarkers and bioaccumulation patterns of contaminants in aquatic organism provides additional information of diet uptake success and its nutritional qualtiy (unit 8). In unit 9, students will be introduced to future challenges of pathways and mechanisms of aquatic energy flow, predator-prey interactions, community structure, and contaminant dynamics. This course provides integrative knowledge of how diet flow, if properly characterized, represents a metric of ecosystem health. This course will also include guest lectures from scientists of the United Nations and other prominent food web researchers.

Course topics:
1. Introduction to trophic biomarkers;
2. Carbon and energy budgets in terrestrial and aquatic ecosystems; 3. Energy provision to aquatic consumers;
4. Energy utilization by aquatic consumers;
5. Contaminants in aquatic food webs;
6. Trophic tracers in aquatic food webs - stable isotopes;
7. Trophic tracers in aquatic food webs - lipids, fatty acids, and compound-specific stable isotopes;
8. Trophic tracers in aquatic food webs - trace metals and emerging xenobiotics;
9. Future challenges - how will nutritional composition in aquatic food webs change with climate change ?