AUTHOR=Yang Jingru , Yang Jinling , Chen Mingqiang , Fu Zhengyi , Sun Jing , Yu Gang , Wang Aimin , Ma Zhenhua , Gu Zhifeng 

TITLE=Physical Responses of Pinctada fucata to Salinity Stress

JOURNAL=Frontiers in Marine Science

VOLUME=8

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2021.792179

DOI=10.3389/fmars.2021.792179

ISSN=2296-7745

ABSTRACT=<p>This study was conducted to understand the changes of physiological and biochemical indexes of black and red shell <italic>Pinctada fucata</italic> under acute high and low salt stress. In this study, the salinity of 35‰ was used as the control, while the salinities of 20 and 50% salinity were used as the low and high salt treatment groups, respectively. The osmotic pressure (OSM) and ion concentration in the hemolymph, Na<sup>+</sup>-K<sup>+</sup> -ATPase (NKA) activity and respiratory metabolism in gills, and antioxidant and immune (non) enzymes in the hepatopancreas of <italic>P. fucata</italic> with two shell colors were compared and analyzed at the time periods of 1.5 and 3 h post-salinity stress. The results showed that the OSM and inorganic ion (Na<sup>+</sup>, Ca<sup>2+</sup>, and Cl<sup>–</sup>) concentration in the hemolymph of the black and red <italic>P. fucata</italic> increased significantly with the increase of salinity after the time periods of 1.5 and 3 h. At 3 h, the black <italic>P. fucata</italic> NKA activity decreased significantly with the increase of salinity, while red <italic>P. fucata</italic> reached the highest value at high salinity. The succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH) activities of red <italic>P. fucata</italic> showed U-shaped and inverted U-shaped distributions with the increase of salinity after 1.5 h, respectively. With the increase of salinity, the phenoloxidase (POX) activity of red and black <italic>P. fucata</italic> showed inverted U-shaped and U-shaped distributions, respectively. The contents of glutathione (GSH) and vitamin C (VC) in black <italic>P. fucata</italic> decreased significantly with the increase of salinity at 1.5 and 3 h. Red <italic>P. fucata</italic> GSH and VC reached their maximum value in the 1.5-h low salinity group and 3-h high salinity group. The vitamin E (VE) content in black <italic>P. fucata</italic> increased significantly with the increase of salinity at 1.5 h, and reached the maximum at 3 h in the control group. Red <italic>P. fucata</italic> VE reached the maximum at 1.5 and 3 h in the control group. The results obtained from the present study revealed that the sensitivity of <italic>P. fucata</italic> to salinity varied in shell color. Compared to black <italic>P. fucata</italic>, red <italic>P. fucata</italic> responds more quickly to sharp salinity changes, thereby reducing more likely damage. Compared with a high salt environment, <italic>P. fucata</italic> was more adaptable to the changes of acute low salt environment. The results obtained from the present study provide the physical references for subsequent selective breeding of this species.</p>