Study on the feeding habits of fishery organisms in the Yangtze River estuary and the southern Yellow Sea in spring with δ13C method

The Yangtze River estuary and the southern Yellow Sea are the natural habitats for numerous marine organisms. These systems are influenced both by oceanic water and the runoff. The main objectives of this study were to compare the feeding habits of organisms from these two areas using stable isotopes to calculate the percent reliance on benthic prey and to compare the results of stomach content analysis from the previous researches the carbon stable isotope technique. The ratios of carbon stable isotopes (delta C-13) of 19 fish species and 12 invertebrates in the Yangtze River estuary, and 14 fish species and 10 invertebrates in the southern Yellow Sea in spring, 2005, were examined. The results showed that there were 10 fishery species that had the same feeding habits in the Yangtze River estuary and the southern Yellow Sea. The percent reliance on benthic prey of organisms in the southern Yellow Sea was mostly higher than those of organisms in the Yangtze River estuary. If the feeding habits types of the two methods were identified using only pelagic feeding, benthic feeding and mixed feeding habit three categories, there were 20 out of 23 organism species that had the same feeding habits. The study showed that the feeding habits of fishery organisms had spatial variations, and the carbon stable isotope technology can be used to calculate the feeding habits of organism practically.