Compound specific-isotope analysis: exploring a novel tool to study parasitic trophic interactions
Stable isotope analysis is widely used to identify trophic interactions and to determine trophic positions of organisms in food webs. This method makes use of the differences between isotopic ratios of naturally occurring stable isotopes of carbon (δ13C) and nitrogen (δ15N) between consumers and their resources. δ15N values are used to determine trophic position, based on an empirically derived average difference (trophic discrimination factor or Δ15N) of, on average, 3.4‰ between trophic levels. While the method has been extensively used to examine predator-prey and herbivore-plant relationships, other potentially major components of food webs such as host-parasite interactions have been largely overlooked to date. In addition, the existing studies suggest that parasitic trophic interactions may exhibit very different discrimination factors. A potential novel tool to study parasitic and other trophic interactions is the use of compound-specific isotope analysis, which focusses on the δ15N of amino acids instead of using bulk tissue samples. One of the potential advantages of this method is an increased accuracy of determining trophic levels due to a larger trophic discrimination factor of about 8.0 ‰. This MSc project will explore the potential of this novel method for studying unusual trophic interactions such parasitism by comparing bulk and compound-specific measurements of various parasites and their hosts.
No prior experience with the topic required. The project would suit a MSc student with an interest in biochemistry, isotope ecology, marine ecology, or parasitology as it will include a mix of field work (sampling and dissections of hosts and parasites) and sophisticated analytical laboratory work (sample preparation, isotope measurements).