Biochemical tracers in freshwater ecosystems

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Lipids, including fatty acids, are sensitive indicators of stress that respond, in predictable ways, to changes in the environment. Some fatty acids are critical to the maintenance of optimal physiological performance in all animals including humans. Those fatty acids are called essential fatty acids (EFAs). In mammals EFAs are known to be important in the maintenance of cardiovascular and neural health. In invertebrates and fish they are known to promote normal development, growth and reproduction. EFAs are primarily produced in aquatic ecosystems and from there are transferred to terrestrial ecosystems via a variety of mechanisms (predation, insect emergence, shore drift etc). Therefore it is critically important to understand global threats to their production and distribution within aquatic ecosystems and between aquatic ecosystems and neighboring terrestrial ecosystems. Three large-scale stressors that have the potential to impact the production of EFAs at the base of the food chain (i.e. in algae). These include; climate change, exotic invaders and eutrophication. Another special feature of fatty acids is their ability to act as biomarkers (compounds that are passed, unchanged, from one organism to another through the processes of herbivory or predation). This project is targetted towards; a) a detailed examination, in the laboratory, of the effects of climate change (temperature increases) on the production of EFAs in algae including their transfer to zooplankton (herbivores), b) refining and developing new biochemical tracers that will allow researchers to track the flow of carbon associated with exotic invaders (zebra mussels) throughout the aquatic food web and thus gain a deeper understanding of the full scale of exotic invader impacts, and, c) showcase how EFAs, produced in algae, are retained, through time, in selected regions in the the brains of mice as they age. A more thorough understanding of the global threats to EFA production and how this may affect their transfer to terrestrial organisms will provide us with a new and powerful incentive to conserve our unique and precious freshwater ecosystems.