3.3 δ13CEAA fingerprints across Baltic regions
The δ13CEAA fingerprints of clupeids from the four Baltic Sea regions show region-specific clustering of most herring and sprat specimens (Fig. 5A and 5B). The separation was stronger for herring (Pillai’s Trace = 1.05, F6,32 = 5.9; P < 0.001) than for sprat (Pillai’s Trace = 0.90, F6,32 = 4.4; P < 0.01) due to larger principal component variability of the Arkona Basin specimens. The region-specific separation becomes weaker when joining the two clupeid species (see Fig. S1). To assess how ontogentic factors may have influenced the observed δ13CEAA fingerprints, we incorporated mass of individual specimens as a covariate using MANCOVA. The significance of these tests are practically similar to those obtained with MANOVA for both herring (Pillai’s Trace = 1.06, F6,30 = 5.6; P < 0.001) and sprat (Pillai’s Trace = 0.94, F6,30 = 4.4; P < 0.01).