Changes in Ammonia Nitrogen and Hydrogen Sulfide Levels in Aquaculture Ponds During High Temperature and Rainy Seasons and Control Measures
Abstract：In crab farming, water quality management is one of the key links. Hydrogen sulfide and ammonia nitrogen are common harmful substances in aquaculture water bodies, and their accumulation can have a negative impact on the growth and health of crabs. The toxicity of ammonia nitrogen varies under different pH conditions, which is due to its dissociation equilibrium in water: NH3 + H+ ⇄ NH4+. When pH > 9, the proportion of toxic molecular ammonia (NH3) exceeds 50%; while when pH < 7, ionic ammonium (NH4+) dominates (with lower toxicity). In the later stages of crab farming, the accumulation of ammonia nitrogen not only directly affects the health of crabs but also further exacerbates the harm by reducing the dissolved oxygen level in the water. For example, in a crab farming base in Jiangsu, due to increased feeding in the early stage and rising water temperature, the ammonia nitrogen level rose above 0.8 mg/L, leading to a significant reduction in crab feeding and slowed growth. The oxidation process of ammonia nitrogen consumes a large amount of dissolved oxygen, causing the dissolved oxygen level in the bottom water to drop to about 3 mg/L, which is below the required level for normal crab growth (4–5 mg/L). Low dissolved oxygen environments can lead to weakened immunity in crabs, reduced resistance to diseases, and easy outbreaks of disease, resulting in economic losses.
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Publication Date：2025-11-10
Online Publishing Date：2025-12-04(First online date of this platform, not the publication date of the document)
Pages：2( 27-28 )