Survival, growth and physiology of marine bivalve (Sinonovacula constricta) in long-term low-salt culture

In this study, we investigated the possibility of rearing and breeding the razor clam (Sinonovacula constricta) in inland low salinity water or freshwater. Long-term low salinity (LS) rearing was performed for 3 months to determine the effects of LS on the survival rate, growth rate, and the activities of critical enzymes in juvenile S. constricta (JSC). The survival rate in the LS group was only 15.67% at the end of the LS rearing test. In the first month, the survival rate in the LS group was significantly lower than that in the control group (P < 0.001). The growth rate (shell length growth rate and weight gain rate) was significantly lower in the LS group than the control group in the first month (P < 0.001 for length and weight). However, the growth rates in the two groups differed little during the second and third months. The oxygen consumption and ammonia excretion rates by JSCs were significantly higher in the LS group than the control group during the first month, but they decreased gradually during the following 2 months. The Na(+)/K(+) ATPase and superoxide dismutase activities were significantly higher in the LS group than the control group during the first month, but they then decreased gradually until there were no significant differences between the groups. However, the aspartate aminotransferase activity was higher in the LS group than the control group during all 3 months. Most of the JSCs died due to LS but the survival of some JSCs suggests the possibility of breeding LS resistant or freshwater S. constricta.