Characteristics of C and O stable isotope in otolith of juvenile Coilia nasus from the Changjiang River Estuary

For better understanding of the characteristics of stable carbon(δ13C) and oxygen(δ18O) isotopes in the otolith of Coilia nasus and the possible ecological significances, the analysis of otolith stable isotope ratios of δ13C and δ18O was conducted using an isotope ratio mass spectrometry on C. nasus juveniles collected from the Changjiang River Estuary. The otolith revealed δ13C and δ18O values of –12.1±1.8(‰VPDB) and –7.9±1.2(‰VPDB), respectively. Unlike δ18O, δ13C generally varied in a relatively wide range. Two groups of the fish could be separated based on scattered distribution by otolith δ13C and δ18O values of all C. nasus individuals in the present study, suggesting possible different natal origins(i.e. spawning/nursery areas) in the Changjiang River. The different environments with different water temperature and food organism composition might be experienced by the two groups of C. nasus fish.