Culture of oyster Crassostrea angulata in Taiwan is over hundred years, and the major cultural sites are along the west coast. This study was aimed to investigate the effects of environment and genetic inheritance to growth and reproduction through transplant experiments conducted in Taixi and Qigu during the period of June 2011 to July 2012. The shell length, shell weight and total weight increased with time, base on monthly examination on the groups of Taixi (T), TaixiQigu (T¡¦), Qigu (Q) and QiguTaixi (Q¡¦). Although group Q had the greatest shell length, shell weight and total weight, their regression slopes were significantly smaller than all other groups. The greatest relative increment of shell weight was in the first month and group T had the highest increment compared with others. The highest and lowest CI values were in groups T and Q, respectively. Sex ratio of oysters cultured in Taixi (groups T and Q¡¦) showed male-biased trend while female-biased trend was observed in Qigu (groups Q and T¡¦). In addition, the GSI values increased earlier in Taixi than in Qigu. A similar pattern in GSI variations has been observed in the native and transplanted groups. As a whole, genetic and environmental factors both had influence on oyster growth. Group Q had the lowest weight gain which might be resulted from high cultural density in Qigu. Thus, each individual obtained less amount of food than in Taixi. After a half-year culture, the reproductive cycle of transplanted oysters was similar to local groups indicated the contribution of environment is more important than genetics to oyster reproduction in later cultural stages.

The present study was undertaken to evaluate the effects of stress on crystalline style characteristics in bivalves of Crassostrea angulata, Meretrix lusoria, and Perna viridis. Firstly, the crystalline style morphological characteristics in normal submerged condition was examined. The presence percentage of crystalline styles in C. angulata collected from different months ranged from 0 to 73%. While, it was 100% in M. lusoria and P. viridis. Secondly, the crystalline style morphological characteristics were investigated under stresses of starvation, hypoxia and desiccation. In C. angulata, the crystalline styles were absent after treated with each of the unfavorable conditions for 1 hour. In M. lusoria, under starvation and hypoxia conditions for 72 hours, the presence percentage of crystalline styles was significantly decreased. Even more, the presence percentages of crystalline styles in M. lusoria reduced to 22% when treated with desiccation for 2 hours. In P. viridis, the presence percentage of crystalline styles was 100% under starvation and hypoxia for 72 hours. In contrast, the mussels were totally dead under desiccation for 72 hours. By comparison, desiccation had greater influence on the three bivalves than starvation and hypoxia based on the standardized crystalline style wet weight (crystalline style wet weight/ shell length). Additionally, the presence percentage of crystalline styles in C. angulata was also influence by fed. In all, among the three examined species, oyster C. angulata is the most sensitive one to unfavorable conditions.