Sanguinolaria rostrata is a deep site-burrowing bivalve commonly found in the southwest coastal waters of Taiwan. It has a long siphon extending to the surface. It is reported that exposed S. rostrata dies in few days without silt. However trussing it up rubber bands or cut off the hinge, it can survive for over one month in the laboratory. In this study the relation of shell closing and mortality for S. rostrata were examined and compared with the hard clam Meretrix lusoria in the similar environments. The size of adductor muscle and its ratio to the shell size, the strength of shell closing and the tissue structure of adductor muscle were examined. The quantities of fructose 2,6- biphosphate, an intermediate of glycolysis, in the adductor muscle of S. rostrata were determined. The results indicated that the average strength of closing shell for S. rostrata was 36.65% and for M. lusoria was 41.19%. The trends of tropic shell closing strength and the size of adductor muscle as well as shell closing strength and the adductor muscle wet weight were the same for the two species. The ranges of strength for muscle closing among S. rostrata of different sizes were smaller than those of M. lusoria. The average ratio of the adductor muscle microfiber to muscle was 55.6¢Mfor S. rostrata and 83.2¢M for M. lusoria. Therefore, the adductor muscle of S. rostrata is looser to M. lusoria. The concentration of fructose 2,6- biphosphate fluctuated widely to the unclamped S. rostrata in the first 6 hours and the concentration reached 7.58£gmole/mg at most. The concentration did not rise between 6 and 24 hours, indicating that unclamped S. rostrata consumed energy within the first 6 hours, then showed no sign of consuming energy.

Abstract The combinations of four temperatures (20, 25, 30, 35¢J) and six salinities (5, 10, 15, 20 ,25, 30psu ) were employed to study the effects of environmental factors on the speed of ciliary movement of the gill and the oxygen consumption of hard clam Meretrix lusoria and purple clam Sanguinolaria rostrata. The results show that, at the same salinities, the speed of ciliary movement of the gill and the oxygen consumption of M. lusoria increased with increasing temperature and reached the maximum at 30¢J, but declined at 35¢J. In contrast , the speed of ciliary movement of the gill and the oxygen consumption of S. rostrata increased with increasing temperature, and the maximum was at 35¢J. S. rostrata can adapt to higher temperature than M. lusoria does. At the same temperature, the speed of ciliary movement of the gill and the oxygen consumption of two bivalves increased with increasing salinity, reaching its maximum at 15~25psu, and declining at higher salinity ranges. These two bivalves like to live in estuaries. The maximal speed of ciliary movement of the gill and the maximal oxygen consumption of M. lusoria occurred at 30¢J, 20 psu (1.23 cm/min and 1.78 mgO2/hr/g, respectively). The ratio of the maximun to the minimun were 2.5 and 2.8, respectively. The maximal speed of ciliary movement of the gill and the maximal oxygen consumption of S. rostrata were at 35¢J, 25 psu (1.64 cm/min and 1.45 mgO2/hr/g, respectively). The ratio of the maximun to the minimun were 4.0 and 5.8, respectively. Temperature and salinity had more remarkable effects on S. rostrata than on M. lusoria. In another experiment, the combinations of four temperatures (20 ,25 ,30 ,35¢J) and three salinities (10, 20, 30 psu) were employed to study the effects on the speed of ciliary movement of the gill and the oxygen consumption of small M. lusoria and small S. rostrata. The results show that the effects of all temperature-salinity combination on the speed of ciliary movement of the gill and the oxygen consumption of the small bivalves were similar to that of the large ones. The physiological conditions of the small bivalves were similar to that of the large ones. The maximal speed of ciliary movement of the gill and the maximal oxygen consumption of small M. lusoria were at 30¢J, 20 psu (1.31 cm/min and 5.56 mgO2/hr/g, respectively). The ratio of the maximun to the minimun were 2.5 and 3.0, respectively. The maximal speed of ciliary movement of the gill and the maximal oxygen consumption of small S. rostrata were at 35¢J, 20 psu (1.67 cm/min and 3.96 mgO2/hr/g, respectively). The ratio of the maximun to the minimun were 2.9 and 7.1, respectively. Temperature and salinity had more remarkable effects on small S. rostrata than small M. lusoria. Our results also show that the oxygen consumption is positively correlated with the speed of ciliary movement of the gill in both bivalves (R2¡á0.94). The speed of ciliary movement of the gill can be regarded as an physiological indicator. The speed of ciliary movement of the gill of M. lusoria changed very significantly when the temperature was suddenly changed 5¢J or when the salinity was suddenly changed 10psu. The condition then stabilized only gradually. The speed of ciliary movement of the gill showed no pronounced variations after 50~70 minutes. We found that when the temperature or salinity was changed suddenly, the physiological condition of M. lusoria was disturbed and became stable after 70 minutes. M. lusoria died at 5psu (35¢J), but S. rostrata didn¡¦t. S. rostrata can adapt to higher temperature and lower salinity. The cultivation of S. rostrata is easier than M. lusoria. The effects of temperature changes were more significant than those of salinity. Temperature variations were more important than salinity variations on cultivation of M. lusoria and S. rostrata.

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.