Natural Carbon Isotope Tracers in Arctic Aquatic Food Webs

Natural isotope abundances, both stable and radioactive, have emerged as powerful means of tracing ecosystem energetics and estimating the dependence of organisms on specific habitats or ecosystem processes. Although the complexity of lower-latitude ecosystems often confounds the investigator through the dilution of isotopic signals from multiple sources, in several instances the technique has proven extremely valuable in sorting out food web or energetic pathways [see the excellent review by Fry and Sherr (1984), which documents the rapid growth of the field and its successes]. When multiple isotopic signals are available, the chances of finding useful information increase dramatically. This study illustrates the combined application of the radioisotope and the stable isotopes of carbon in sorting out the energy dependencies of arctic tundra biota.