Transverse Variation of Food Compositions of <i>Corbicula bivalves</i> in a Tidal River with Series of Groins

Abstract

This study was conducted to clarify the food compositions of Corbicula bivalves ( C. japonica and leana ) in tidal rivers with varied landscapes. In order to grasp their trophic structures, we measured the carbon and nitrogen stable isotope ratios of the collected samples such as the bivalves with varied growth stages and the suspended particulate organic matters (SPOMs) with varied landscapes as their food sources, and then analyzed their relationships with IsoSource mixing model software. The stable isotope ratio measurements clarified that there was a large difference in the ranges of C. japonica and leana in spite of the same sampling locations, and the IsoSource analysis could quantitatively describe their food compositions. According to the results, it could be clarified that the variations in food compositions were dependent not only on the species difference but also on their growth stages. Furthermore, it might suggest that their diet preferences affected the spatial distributions of these Corbicula bivalves in this location.