Ammonia Toxicity Effects in Aquatic Organisms

Ammonia, present in aquatic environments primarily as un-ionised ammonia (NH₃) and its protonated form ammonium (NH₄⁺), exerts a range of toxic effects on fish, shellfish and other aquatic biota. Originating from natural nitrogen cycling, agricultural runoff and intensive aquaculture, elevated ammonia concentrations disrupt ionoregulation at the gill surface, induce oxidative stress, impair immune function and alter behaviour and growth. Un-ionised ammonia readily diffuses across gill epithelia, elevating internal ammonia levels that provoke cellular damage, neurotoxicity and metabolic dysfunction. Chronic exposure can suppress antioxidant defences, lead to bioaccumulation in key tissues, and trigger inflammatory responses and apoptosis. Such impacts compromise population health and productivity in wild and cultured stocks, with far-reaching implications for biodiversity, food security and ecosystem resilience in the face of intensifying nutrient loads and climate-driven changes in water chemistry.

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Ammonia Toxicity Effects in Aquatic Organisms publication trend

The graph below shows the total number of articles in ammonia toxicity effects in aquatic organisms across all publications each year (not limited to Nature Index journals).

Technical terms

Un-ionised ammonia (NH₃): The toxic, membrane-permeable form of ammonia that diffuses across biological membranes.

Ammonium (NH₄⁺): The protonated, less toxic form of ammonia predominant at lower pH.

Oxidative stress: Cellular damage resulting from an imbalance between reactive oxygen species production and antioxidant defences.

LC₅₀: The lethal concentration of a substance at which 50% of test organisms die within a specified period.

Bioaccumulation: The uptake and retention of a toxicant in an organism’s tissues at concentrations higher than in the surrounding environment.

References

1. Ammonia and aquatic ecosystems – A review of global sources, biogeochemical cycling, and effects on fish. The Science of The Total Environment (2023).
2. The Impact of Acute Ammonia Nitrogen Stress on the Gill Tissue Structure and Antioxidant Ability of Gills and Red and White Muscle in Juvenile Yellowfin Tuna (Thunnus albacares). Antioxidants (2024).
3. Effects of Curcumin on Oxidative Stress and Ferroptosis in Acute Ammonia Stress-Induced Liver Injury in Gibel Carp (Carassius gibelio). International Journal of Molecular Sciences (2023).