Metabolic characteristics and adaptability of a new variety of sea cucumber “Shenyou No.1” under different salinities

Abstract:

Salinity is a key ecological factor for the survival of the sea cucumber (Apostichopus japonicus), and analysis of the adaptation and tolerance mechanisms of new sea cucumber varieties can provide a scientific basis for their promotion. To study the adaptation of a new variety of sea cucumber, “Shenyou No. 1,” the growth, survival, respiratory metabolism, and immune enzyme activities in different salinities (ranging from 14 to 40) were measured. The results revealed that the survival rate was 100% within the salinity range of 23~40, whereas all seedlings died when the salinity was below 16. The specific growth rate (SGR) was positive within the salinity range of 23~40 and reached a peak within the salinity range of 29~37, with the highest SGR being 0.9932%/d at a salinity of 32. With a change in salinity, the oxygen consumption rate and ammonia excretion rate showed a “M” type change, with the trough values obtained at a salinity of 32 with values of 0.0130 mg/(g·h) and 0.00138 mg/(g·h), respectively. The O/N ratio showed no significant difference with the change in salinity. The ACP, AKP, LZM, and SOD activities changed significantly under the high and low salinity stresses. During the adaptation period, the peak of SOD enzyme appeared at 0 d, whereas the peak of ACP and AKP appeared at 10 d, and the peak of LZM appeared at 10~20 d. All the results indicated that the suitable salinity range for the new variety “Shenyou No. 1” was 23~40 and the optimum salinity range was 29~37. Changes in the salinity led to changes in the respiratory metabolism and immune enzyme activity of the seedlings. These results provide a scientific basis for the promotion of the new variety of sea cucumber “Shenyou No. 1.”