| The razor calm (Sinonovacula constricta) belongs to estuarine shellfish. The salinity fluctuation is an important source of pressure for shallow water habitats. High salinity in some coastal areas of Shandong and Jiangsu has a certain impact on the survival and germplasm conservation of razor calm.Two populations of razor calm were used as experimental materials, including "Shenzhe No.1" population (SZSC) and natural population (ZRSC). The semi-lethal salinity of each population was determined. Non-stress group and stress group were set up under high salinity. The effects of control group (20) and high salinity (24,28,32) on burrowing behavior and feeding behavior of razor calm were studied. The differences of burrowing indexs and feeding rate between the two populations were compared. The results showed that the semi-lethal salinity of SZSC was 34.64, while the semi-lethal salinity of ZRSC was 32.34. The burrowing behavior of razor calm could be divied into four periods: the preparation period of shell closure, the period of axe foot movement, mud digging period and the end period of mud diving. In the non-stress group, the burrowing time of 50 % (BT50) of SZSC was significantly higher than that of ZRSC(P<0.05). The BT50 of SZSC at 24 salinity was the minimum. The distribution of burrowing depth of SZSC was more concentrated, 50% of the individuals are between 7.29 and 7.55 cm. And the burrowing rate was 88.33 % at 32 salinity, which was significantly higher than that of ZRSC(P<0.05). In the stress group, the BT50 of SZSC was significantly lower than that of ZRSC, and the burrowing rate was significantly higher than that of ZRSC(P<0.05). With the increase of salinity, the burrowing rate of ZRSC decreased significantly(P<0.05). The average burrowing depth of ZRSC was 7.45 cm at 32 salinity, which was significantly higher than that of SZSC(P<0.05). By comparing the experimental results of two populations, whether in SZSC or ZRSC, the BT50 of razor calm in stress group was higher than that in non-stress group at each salinity. However, there was no significant difference in BT50 between stress group and non-stress group at 20 and 28 salinity among SZSC(P>0.05). The BT50 of SZSC was closer to that of the control group at 24 and 28 salinity, and the Vitality of SZSC is significantly better than that of ZRSC after 24 h of salinity stress. Under the condition of high salinity, the distribution of SZSC in mud is more concentrated than that in ZRSC, and the burrowing depth is shallower. In terms of feeding behavior, the feeding rate of SZSC was significantly higher than that of ZRSC under high salinity(P<0.05). The feeding rate of SZSC reached the maximum 89.54 mL/(g·h) at 24 salinity, which was significantly higher than that of other salinity groups(P<0.05). In summary, the ecological behaviors of two populations will be affected by high salinity. The higher the salinity, the stronger the stress response, and the SZSC has better tolerance to high salinity. In this study, the tolerance of two populations of razor calm to high salt was evaluated at the level of ecological behavior for the first time, meanwhile, the vertical distribution and feeding ability of Sinonovacula constricta in sediment under high salt environment were revealed. The results provide a theoretical reference for further breeding of new high-salt-tolerant strains of S. constricta. |
