Here at SUERC’s Stable Isotope Ecology Laboratory, we’re fascinated by how measuring stable isotopes can answer many questions about animal ecology. We’re a small team with a wealth of mass spectrometry experience, and a set of instrumentation that rivals much larger departments. Much of our funding comes from NERC via the NEIF – the National Environmental Isotope Facility which encompasses a range of mass spectrometric facilities located across the UK, covering a range of earth, environmental, archaeological and ecological sciences and different technologies.
At the SUERC Stable Isotope Ecology Laboratory, our techniques are geared towards elucidating two main themes: food webs, or diet; and animal movement.
In many cases an animal’s diet may be observed directly, or indirectly via the analysis of faecal samples (though the latter may not identify an individual). In other cases, determining the diet of a particular species might require a more invasive approach such as gastric lavage, though this only works for certain taxa. Gut content analysis is obviously a destructive approach, requiring the sacrifice of individuals. In contrast, stable isotope analysis integrates diet over a longer time period, offering an alternative approach which is often non-destructive, at least for large taxa, and in many cases, non-invasive. Stable isotope ratios of animal tissues reflects (with some slight modification) those of diet. Estimates of the proportions of foods in an animal’s diet can then be quantified by careful use of stable isotope mixing models.
The methods for tracking animal movement using stable isotopes is basically an extension of those used for elucidating diet: animals that move from one habitat to another (sometimes but not always requiring a change of diet) will take on stable isotope signatures of the new environment. It is particularly informative for those animals which are too small to attach transmitters, for example insects and small passerines, or cryptic animals which are seldom seen by observers (e.g. marine mammals and fish). The big advantage of stable isotope techniques over extrinsic methods such as bird ringing or loggers is that the individual only needs to be captured once (i.e. there is no mark and recapture): all of the isotopic information can be gleaned from the appropriate tissue.
A fuller description of stable isotope ecology is here: