Grant: Research Tools and Instruments - Category 1 (<$150,000)

All animals, including humans, are embedded in food webs. An organism's position within a food web, as well as other factors, determines the amount of energy and nutrients it receives and is critical for survival. Understanding the structure of, and the flow of nutrients through, food webs is a critical component of ecology and a necessity for proper management and conservation of healthy ecosystems. Unfortunately, food webs are notoriously difficult to quantify and there is much that is unknown about the mechanisms that shape food webs. With impending global change, it has never been more critical to understand the factors that structure food webs and how anthropogenic stress may influence this. Food webs can be characterized using stomach contents, stable isotopes of bulk samples, and fatty acids, however these methods and chemical tracers often do not provide the resolution or detail needed to understand complex food webs or ecosystems, such as those in the Great Lakes. Very recently, new methods and instrumentation have been developed that allow the measurement of stable isotope ratios of individual compounds, such as fatty and amino acids, which can provide unparalleled specificity in establishing trophic links and nutrient pathways in food webs and ecosystems. Methods have also been developed to measure isotope ratios of anthropogenic contaminants, such as PCBs, that can be used to identify specific sources of these contaminants in the environment. This proposal requests funding to purchase a gas chromatograph equipped with an autosampler and interface for an isotope ratio mass spectrometer to allow for measurement of stable isotope ratios of individual compounds that will allow validation and application of this novel method to ecological and environmental research.