Heritability estimates for copper/zinc accumulation capabilities and correlation with growth/quality traits in the Fujian oyster, Crassostrea angulata

Oysters are hyper-accumulators of copper (Cu) and zinc (Zn) and are a good food source for trace element supplements. However, increasing heavy metal pollution in estuaries and coastal areas has posed a critical threat to oysters and thus led to food safety issues. Here, we assessed if it is possible to obtain oyster varieties with differential metal-accumulated properties through genetic improvement. The narrow-sense heritabilities of Cu and Zn accumulation capabilities and growth traits in Fujian oyster (Crassostrea angulata) were estimated to determine the degree to which Cu and Zn accumulation is under genetic control. In addition, we investigated the trade-offs between Cu/Zn accumulation and some farming performances, including growth-related traits, and the contents of glycogen and eight free amino acids. Moderate estimates were observed for narrow-sense heritability of Cu (0.189 +/- 0.061) and Zn (0.373 +/- 0.091) accumulation capability, while growth-related traits showed moderate-high heritability (0.168 +/- 0.059-0.595 +/- 0.116). High-level genetic (0.802 +/- 0.080) and phenotypic (0.853 +/- 0.012) correlations were detected between Cu and Zn accumulation capability, while correlations between metal accumulation and growth traits were low (-0.023 +/- 0.042-0.491 +/- 0.200). Moreover, Cu and Zn accumulation in Fujian oyster exhibited no significant influence on the quality traits measured, except for Taurine (Tau). Tau contents in high Cu/Zn accumulated oysters were significantly higher than in low-accumulated oysters, suggesting an important role of Tau in Cu/Zn accumulation. Our results provide important information to guide effective selective breeding of Fujian oysters with specific Cu/Zn accumulation capabilities.