To test the potential of diet switching experiments in ecophysiological studies of marine invertebrates, stable carbon isotope ratios were measured at different seasons in the gonad, adductor muscle, digestive gland and gills of scallops (Pecten maximus) and oysters (Crassostrea gigas) held for 15 days on a constant diet of phytoplankton depleted in 13C. The aim of this study was to determine if differences in carbon incorporation could be detected among species, seasons and organs, and if so, whether it was consistent with their known energy-allocation patterns. After offering the new diet, isotope values of the different organs gradually shifted and significant differences among organs, seasons and species were found. A carbon incorporation index (CII)... |