Carbon and nitrogen stable isotope (δ13C and δ15N) values of individual Spirit Lake rainbow trout (O. mykiss). “Snails” ellipses are defined by means ± standard deviations of P. antipodarum (black), and G. deflectus (white). “Trophic snails” ellipses and arrows represent the values for the same snail species after they have been adjusted to account for isotopic trophic differences between trout fin and snail tissue samples (mean ∆13Csnail-trout = 1.0‰, Jensen et al. 2012; mean ∆15Nsnail-trout = 1.7‰, Heady and Moore 2012).