Isotopic niche provides an insight into the ecology of a symbiont during its geographic expansion.

The study of the recent colonization of a symbiont and its interaction with host communities in new locations is an opportunity to understand how they interact. The use of isotopic ratios in trophic ecology can provide measurements of a species' isotopic niche, as well as knowledge about how the isotopic niches between symbiont and host species overlap. Stable isotope measurements were used to assess the sources of carbon assimilated by the host species (the bivalves and ) and their associated symbiont pea crab , which occurs within these bivalves' mantle cavities.