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Physiological Response Mechanisms of Triplophysa strauchii Under Salinity Stress
by
and
Shixin Gao
1,2,†, 
Jinqiu Wang
1,2,†,
Kaipeng Zhang
1,2,
Guanping Xing
1,2,
Yunhong Tan
1,2,
Lulu Chen
1,2,
Tao Ai
3,
Shijing Zhang
4,
Yumeng Chen
5,
Zhulan Nie
1,2,* and
Jie Wei
1,2,* 1
College of Life Science and Technology, Tarim University, Alar 843300, China
2
Xinjiang Production & Construction Corps Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin, Alar 843300, China
3
Xinjiang Production and Construction Corps Aquaculture Technology Promotion General Station, Urumqi 830002, China
4
Xinjiang Yutian County Fengze Technology Aquaculture Co., Ltd., Hotan 848400, China
5
Xinjiang Production and Construction Corps 9th Division Animal Husbandry and Aquaculture Development Center, Tacheng 834300, China
*
Authors to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Biology 2025, 14(9), 1202; https://doi.org/10.3390/biology14091202
Submission received: 14 July 2025
/
Revised: 11 August 2025
/
Accepted: 29 August 2025
/
Published: 5 September 2025
(This article belongs to the Special Issue Metabolic and Stress Responses in Aquatic Animals)
Simple Summary
Rivers in northwest China have changing salt levels, which threaten a local fish called Triplophysa strauchii. As such, we studied them to find out how much salt they can take and how their bodies react. We tested six different salt levels and a freshwater group, watching how many fish survived, how they acted, and how their bodies worked over four days. We found that half of the fish died when the salt level reached 13.31 ppt, and a safe level was 4.05 ppt. Their gills and kidneys quickly adjust to control water and salt, but their liver and intestines react more slowly. If salt levels stay below 13.31 ppt, the fish can stay healthy. But above 14.3 ppt, their bodies get out of balance, their ability to fight off harm stops working, and they get irreversible physiological dysfunction. This helps us protect these fish by controlling river salt levels, especially in dry areas where salt builds up, keeping their populations safe.
Abstract
Salinity, a critical environmental factor for fish survival, remains poorly understood in terms of how Triplophysa strauchii, a characteristic fish in Northwest China, physiologically responds to salinity stress. This study aimed to determine its salinity tolerance threshold and explore the associated physiological damage mechanisms. Six salinity gradients (11, 11.7, 12.5, 13.3, 14.3, 15.1 ppt) and a freshwater control group were established. Acute toxicity tests recorded mortality and behavior, while physiological–biochemical assays measured ion concentrations and enzyme activities in gills, kidneys, liver, intestines, and plasma over 96 h. The results showed a 96-hour median lethal concentration of 13.31 ppt and a safe concentration of 4.05 ppt. Gills and kidneys, as primary osmoregulatory organs, responded rapidly, whereas the liver and intestine lagged. Salinity ≤ 13.3 ppt allowed the fish to maintain homeostasis via physiological adjustments, but ≥14.3 ppt caused ion imbalance, immune function was significantly suppressed, and irreversible damage. These findings clarify the species’ salinity adaptation strategies, providing a basis for further research on chronic salinity stress.
