| The Crassostrea ariakensis, an economically significant bivalve inhabiting estuarine areas along the coasts of China, plays a crucial role in providing essential ecological services.However, limited studies has been conducted on its physiological response to the highly variable and frequent salinity fluctuations in these estuaries. In this study, various salinity gradients were established to investigate and analyze the change in respiration rate, ammonia excretion rate, O:N ratio, ingestion rate, and clearance rate of C. ariakensis after treatment. Additionally, the effects of CarHSP70、CarHyou1、CarDNAJC2 were examined. The results indicate that within a salinity range of 5-45, the respiration rate and ammonia excretion rate of the C. ariakensis initially increased and then decreased with peak values observed at a salinity of 35. Regarding ingestion and clearance rates, the C. ariakensis exhibited an initial increase followed by decrease within the same salinity range.The maximum clearance rate was observed at a salinity of 15 whereas it reached its lowest value at a salinity of 45. In addition, the research revealed significant impacts of salinity stress on gene expression such as CarHsp70 in the C. ariakensis. The qRT-PCR results show that the three genes are expressed in the gills, mantle tissue, tissue adductor muscle, and lip tissue of the C. ariakensis, with the highest expression level in the adductor muscle. Salinity changes significantly affect the expression of the three genes CarHsp70, CarHyou1, and CarDANJC2 in the Hsp family of the C. ariakensis.After salinity stress, the expression levels of the three genes in gill tissues showed an upward trend. When salinity increased by 10, the expression levels of CarHsp70, CarHyou1, and CarDANJC2 were upregulated to 4.36 times, 3.58 times, and 2.08 times those of the control group; when salinity decreased by 10, it will be adjusted to 3.62 times, 2.97 times, and 2.05 times. When salinity increases by 20, the expression levels of the three genes are 7.13 times, 4.68 times, and 2.72 times that of the control group, respectively; when salinity decreases by 20, they are 5.92 times, 6.04 times, and 2.54 times that of the control group. This study reveals the physiological and molecular responses of C. ariakensis under different salinity conditions, including respiration rate, ammonia excretion rate, ingestion rate, and clearance rate, and the expression changes of Hsp family genes in response to salinity stress, providing reference materials for further understanding the adaptation of oysters to changes in salinity environments. |
