Ten years of experimental animal isotopic ecology

Abstract

Summary Ten years ago Gannes et al. (1997, Stable isotopes in animal ecology: assumptions, caveats, and a call for laboratory experiments. Ecology , 78 , 1271-1276, 1998) identified four major areas requiring further research in experimental animal isotopic ecology: (i) the dynamics of isotopic incorporation, (ii) mixing models, (iii) the problem of routing, and (iv) trophic discrimination factors. 2. Differences in isotopic incorporation rates among tissues seem to be explained by variation in protein turnover. The application of multi-compartment models to isotopic incorporation data has revealed that different inferences can be derived between these and one-compartment models. 3. A variety of mixing models of varying degrees of complexity and realism are used to find the contribution of isotopic sources to the elements in an organism's tissues. The use of these models demands the use of tissue to diet discrimination factors that are rarely measured experimentally. 4. Mixing models assume that assimilated nutrients are disassembled into their elemental components and that these elements are reassembled into biomolecules. This assumption is unrealistic as macromolecules are routed differentially into tissues. Isotopic routing is an area that isotopic ecologists have neglected in their experimental and modelling research. 5. Isotopic ecologists are just beginning to understand why 15 N biomagnifies along trophic chains, and to explore the factors that determine the degree of 15 N biomagnification. We review the hypotheses that explain why 15 N biomagnifies up trophic chains. 6. The use of compound-specific isotopic analyses is opening new fruitful areas of research at the intersection of nutritional and isotopic ecology.

Reconstruction of breastfeeding and weaning practices using stable isotope and trace element analyses: A review

“…In other words, researchers need to know when the studied tissue was synthesized in the individual's life and how large was the lag time between the actual dietary change and the incorporation of isotopic and trace elemental signals into the tissue. Problems related to the incorporation of elements into body tissues have been intensively discussed in isotope ecology (reviewed by Crawford et al, 2008;Martı nez del Rio et al 2009;Wolf et al, 2009;Boecklen et al, 2011). The assessment of biological age is relatively straightforward in soft tissues because the potential time lags between actual weaning ages and elemental signals are relatively small.…”

“…The quantitative evaluation of contributions from breast milk, weaning foods, and adult foods in subadult diet requires knowledge of these elemental routings. Problems related to the routing of elements from dietary components to body tissues have been extensively discussed in isotope ecology (reviewed by Crawford et al, 2008;Martı nez del Rio et al 2009;Wolf et al, 2009;Boecklen et al, 2011). While carbon, nitrogen, and sulfur atoms in tissue protein mainly reflect those in dietary proteins, carbon atoms in tissue apatite reflect those from the entire diet (Krueger and Sullivan, 1984;Ambrose and Norr, 1993;Tieszen and Fagre, 1993;Podlesak and McWilliams, 2006;Kellner and Schoeninger, 2010;Froehle et al, 2012).…”

The impact of metabolism on stable isotope dynamics: a theoretical framework

“…Ponsard & Averbuch 1999;Harvey et al 2002;Olive et al 2003;Marin-Leal et al 2008). But the number of processes involved and the variability of observed patterns led Wolf et al (2009) to renew their call both for more experiments and the development of theoretical models.…”

Trophic inference in two sympatric sharks, Sphyrna lewini and Carcharhinus falciformis (Elasmobranchii: Carcharhiniformes), based on stable isotope analysis at Malpelo Island, Colombia

“…SIA is an important, effective tool that can be applied to elasmobranch conservation research (Kim et al 2012, Shiffman et al 2012). This technique is based on the premise that heavy isotopes of an element are preferentially retained (e.g., nitrogen isotopes via protein amination/deamination, carbon isotopes via respiration) and that specific ratios of heavy to light isotopes are indicative of specific resource use (e.g., diet and habitat) (Wolf et al 2009) and trophic position (Post 2002). This biogeochemical method allows quantitative analysis of dietary composition and foraging patterns over a range of spatial and temporal scales (MacNeil et al 2005), as well as the examination of more complex questions pertaining to community dynamics, feeding strategies or diet, trophic position, and movement in aquatic organisms (Hussey et al 2012).…”