Statistical analyses
We size-corrected TDFs of muscle and liver tissue with the attempt to
adjust for the variation explained solely by growth (Fry and Arnold
1982). Thus, for all analyses, we used the residuals of the significant
regression of TDFs and fish length. To analyze the variation in TDFs
between weight classes, we conducted four different ANOVAs with
subsequent Tukey´s posthoc comparisons using size-corrected
Δ13C and size-corrected
Δ15N, for the two tissue types muscle and
liver. Additionally, we conducted four linear regressions with the
size-corrected Δ13C and size-corrected
Δ15N, for muscle and liver tissue respectively as
dependent variables and SMR as the predictor in order to analyze the
relationship between TDFs and SMR. We compared SMR between the different
weight classes using an ANOVA with subsequent Tukey´s posthoc
comparisons. The assumptions of normal distribution and homogeneities of
variances were met for all parametric analyses. We used IBM SPSS
(version 25) for statistical analyses.