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.