Abstract:
Objective To investigate the toxic effects of salinity stress on the physiology and tissue structure of juvenile (Silurus lanzhouensis), and to analyze the physiological changes in different tissues and the changes in tissue structure under acute salinity stress to determine the range of its salinity tolerance.
Method Based on the LC50 and Safe concentration (SC) obtained from the acute toxicity test, samples were collected from the 10‰ salinity stress group and the control group at 0 h, 24, 48, 72 and 96 h, respectively, and were analyzed by pathological observation and Superoxide dismutase (SOD), Catalase (CAT), Malondialdehyde (MDA) and Lactate dehydrogenase (LDH) assays to analyze the response mechanism of gill, liver and kidney to salinity.
Result The LC50 of salinity-stressed Silurus lanzhouensis larvae was 12.71‰, 12.11‰, 11.49‰ and 10.88‰ at 24 h, 48 h, 72 h and 96 h, respectively, and the SC was 3.46‰. There were no significant changes in gill tissue enzyme activities under short-term stress (24-48 h), but SOD, CAT, LDH enzyme activities and MDA content were significantly higher (P≤0.05) after 72 h. Liver enzyme activities showed fluctuating responses, with peaks at 24 and 72 h and then decreased. Histopathology showed that salinity stress caused gilllets edema and curling, vacuolization of hepatocytes and necrosis of renal tubules, and the degree of damage increased with the time of stress.
Conclusion Although Silurus lanzhouensis has certain potential of salinity tolerance, the salinity of its culture water should be controlled below 3.46‰, and salinity stress destroys the antioxidant balance and energy metabolism, triggering the progressive damage of multiple organs, and ultimately leading to the collapse of physiological functions. In this study, the salinity conditions suitable for culture of Silurus lanzhouensis were screened out, which provided a theoretical basis for the selection and domestication of Silurus lanzhouensis under the salinity environment, and also provided key data support for the utilization of saline and alkaline water resources in the middle and upper reaches of the Yellow River and the selection of resilient varieties.
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