Stable Isotopes as Tools in Ecological Research

Abstract

Stable isotope analysis has proved to be an extremely useful tool in elucidating many ecological problems, with stable isotope ecology comprising the theme of a series of international conferences ( http://www.isoecol.org ). Stable isotopes can be used as biological tracers in the following ways: (1) to identify sources, for instance in determining the identity of basal carbon in a food web; (2) to distinguish sources, for example to determine whether a breeding animal is using local resources or its own reserves, or when an animal migrates/disperses from one location to another and (3) to quantify relative inputs in a system, for example determining the proportions of different prey items to a consumer's diet. When utilised carefully, stable isotope analysis provides some advantages over conventional methods and an additional device for the ecologist. Key Concepts Stable isotopes are useful tracers of ecological processes. Carbon stable isotopes are useful tools in plant physiology and for tracing carbon sources. Nitrogen stable isotope ratios in animal tissues are useful indicators of trophic level. Combined carbon, nitrogen and sulfur isotope ratios in animal tissues elucidate food webs and trophic niche. Hydrogen and oxygen isotope ratios in animals reflect those of local precipitation. Care is needed when planning isotope food web studies.

An insect isoscape of UK and Ireland

“…Despite their typically lower resolution than that of extrinsic methods, stable isotopes comprise a convenient tool with which to investigate migration. 7,8 In addition, since there is no attachment of bulky equipment the technique is ideal for small taxa. Furthermore, stable isotopes can distinguish migrants from residents within the same species; important since many insect species are partial migrants.…”

“…Intrinsic markers such as stable isotope analysis require only one capture to reveal potential information about origin and are therefore less costly. Despite their typically lower resolution than that of extrinsic methods, stable isotopes comprise a convenient tool with which to investigate migration 7,8 . In addition, since there is no attachment of bulky equipment the technique is ideal for small taxa.…”

Host identification in unfed ticks from stable isotope compositions (δ13C and δ15N)

“…The analysis of the natural stable isotope compositions of organisms has been widely used to identify cryptic trophic interactions in food webs (Newton, 2016). Recent studies revealed its potential to unravel complex interactions between a free-living parasite and its hosts (Stapp & Salkeld, 2009;Schmidt et al, 2011;Demopoulos & Sikkel, 2015).…”

Stable isotopes of a terrestrial amphibian illustrate fertilizer-related nitrogen enrichment of food webs in agricultural habitats

“…Stable isotopes can provide insights in this respect (Robinson, 2001;Rubenstein and Hobson, 2004;Perkins et al, 2014;Newton, 2016). The concept of the isotopic niche is based on the fact that an animal's chemical composition is influenced by what it consumes (Fry, 2006).…”