Identification of the Food Sources-Metabolism of the Pacific Oyster Crassostrea gigas using Carbon and Nitrogen Stable Isotopic Ratios

Abstract

In order to understand food sources-metabolism for the pacific oyster (Crassostrea gigas), the stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) of its gut, gill, and muscle as well as potential food sources (particulate organic matter, sedimentary organic matter, benthic microalgae, seagrass detritus) were determined in Dongdae Bay. Average δ13C and δ15N values reflect that oysters primarily fed on sedimentary organic matter as opposed to suspended organic matter during summer and winter seasons. However, the relatively enriched 15N values of particulate organic matter (>250 μm) and sedimentary organic matter in the summer may be due to the photosynthetic incorporation of 15N-enriched nitrogen (DIN) or the spawning events of bivalves. Specific oyster tissues (gut, gill, and muscle) revealed different metabolic pathways, which were determined through analysis of δ13C and δ15N in each organ. The present results suggest the determination of carbon and nitrogen stable isotopes to be a useful approach in ecological research related to the food sources- metabolism of Crassostrea gigas.