4.3 Towards a complementary toolset: combining new and old methods
Isotope ecologists consider EAA to be among the most powerful carbon tracers because EAA carbon backbones are usually passed through multiple trophic levels with minimal modifications in contrast to bulk carbon. In that light, it is unsurprising that the power to differentiate among functional groups and species was higher for δ13CEAA than the bulk isotopes where it is possible to observe coarse trophic structuring and isotopic baseline differences. Given that the analytical costs for bulk C and N isotope analysis is about 20 times less than for CSIA, the question of applying bulk or CSIA in ecological studies is basically a choice between the need for high spatial and temporal resolution vs. high taxonomic resolution. We show that δ13CEAA provides an unprecedented insight into ecological niches and that it is more powerful than bulk C and N isotopes for tracking migration of fishes.