Osmotic and Adaptive Challenges: Physiological and Biochemical Responses of Fish to Increased Salinity

Authors : Harika Eylül Esmer Duruel, Şeyma Kızılkaya, Figen Esin Kayhan

Pages : 351-364

Doi:10.22392/actaquatr.1658565

View : 84 | Download : 235

Publication Date : 2025-12-01

Article Type : Review Paper

Abstract :Climate change is known to affect abiotic factors in coastal and marine ecosystems. The increase in salinity, caused by climate change-related factors that raise soluble salts above optimal levels, leads to acute stress. This condition can affect the tissues and organs of aquatic animals. In chronic stress conditions, organisms become entirely insensitive to stress factors or organisms may either develop tolerance, resulting in altered growth and reproduction rates. Fish can be examined as bioindicators to monitor salt fluctuations, which may cause osmotic stress at the cellular level, and molecular and biochemical changes that are induced via the production of reactive oxygen species (ROS). In addition, enzymatic activities are particularly affected in mitochondrial functions. Although increasing salinity presents a positive picture in some freshwater fish species by supporting embryonic and larval development and preventing some diseases, species with lower adaptability may be adversely affected by excessive salinity. When examining the effects of salinity stress, analysis of energy metabolism during its acute phase is a common preferred approach due to its rapid and measurable indicators. With the increase in salinity, differences occur at the cellular and hormonal levels (e.g., cortisol, prolactin), reproduction, growth, and development processes. Tolerance and adaptation abilities vary depending on whether they are euryhaline or stenohaline fish species. Advanced analytical methods such as omics techniques, metabolic profiling, and imaging techniques are needed to obtain more detailed results in this field.
Keywords : Tuzluluk, stres, ozmoregülasyon, adaptasyon, İklim değişikliği

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