Carbon-13 depletion in an estuarine bivalve: Detection of marine and terrestrial food sources.

Stable carbon isotope analysis was used to define the food sources of bivalve Chione (Austrovenus) stutchburyi in the Avon-Heathcote Estuary, Christchurch, New Zealand. δ13C values of C. stutchburyi tissue were significantly different (from -16.7‰ to -23.5‰ relative to the PDB standard) at five locations separated by less than 4 km but subject to different hydrological regimes. This is related to differences in the isotopic composition of the suspended particulate matter of the inflowing water. C. stutchburyi is shown to utilise carbon of terrestrial and marine origin depending upon its position within the estuary and local hydrology.