Marine coastal ecosystems are commonly used for the aquaculture of suspension-feeding bivalves, such as oyster, scallops and mussels. The food sources for these bivalves often depend on particulate organic matter and benthic microalgae. Recent studies have suggested that attached microalgae and bacteria also become important food sources for suspension-feeding bivalves. Knowledge of the dietary regime of bivalves is crucial for understanding the coastal food web and cultured bivalve management. The ark shell, , is one of the most important commercial bivalve species in China. They are usually cultured both in raft mariculture and bottom sowing proliferation. However, information on the food sources for cultured 13C and N) and stomach content analysis, this study analyzed the dietary regime of under two different proliferation and culturing modes in May and September 2014, aimed to approach the potential food sources of in this area. Results showed that there was a clear seasonal variation in C value in the raft mariculture area (RMA) in May was significantly lower than that in September, but there was an opposite trend in the bottom sowing proliferation area (BSPA). There were no significant differences in under two proliferation and culturing modes in May, but the in the RMA were clearly higher than those in the BSPA in September. The POMs, mainly including phytoplankton, were the greatest sources of food in the RMA, with a contribution rate of 61.0%-62.9%, followed by attached microalgae (37.2%-39.0%). Comparatively, benthic microalgae was the most important food source in the BSPA, with a contribution rate of 51.7% in May and 72.5% in September. Stomach content analysis showed that Coscinodiscus, Pleurosigma, Nitzschia and . The similarity analysis results indicated the proportional similarity (PS) values between stomach content in the BSPA and the benthic microalgae community were 85.30% in May and 77.20% in September, which may suggest that show a certain selectivity for diatoms of weaker planktonic habit, which sink easily, and for benthic diatoms. Overall, the results can improve our understanding of the biology of , and provide theoretical evidence for scientific aquaculture management of suspension-feeding bivalves under these two proliferation and culturing modes.