The use of stable isotopes to study food webs has increased rapidly, but there are still some uncertainties in their application. We examined the δ 15 N and δ 13 C values of Antarctic euphausiids and copepods from the Polar Front, Lazarev Sea, and Marguerite Bay against their foodweb baseline of particulate organic matter (POM). Interpretations of trophic level were helped by comparison with other approaches and by calibration...