Ammonia Stress Affects Digestive Physiology in Juvenile Yellowfin Tuna

Strategic Insights -

Research published in the Marine Environmental Research journal has explored the impact of acute ammonia stress on the digestive physiology and gene expression in juvenile yellowfin tuna. The study found that different concentrations of ammonia nitrogen can affect the digestive activity of the fish, with ammonia levels below 5 mg/L enhancing digestibility and levels between 5 mg/L and 10 mg/L inhibiting it.

Key Takeaways:

  • The study used natural seawater as a control and ammonia concentrations of 5 and 10 mg/L to measure the levels of digestive enzymes in the intestine, liver, stomach, and pyloric cecum of juvenile yellowfin tuna.
  • Ammonia concentrations of 5 mg/L inhibited liver amylase (AMS) and lipase (LPS), while promoting pepsin after 24 h and both AMS and LPS after 36 h in the foregut.
  • The inhibition of LPS activity in the foregut was significantly higher in the 10 mg/L group than in the control group.
  • The study found that different ammonia nitrogen levels can affect the digestibility of juvenile yellowfin tuna, with levels below 5 mg/L enhancing digestibility and levels between 5 mg/L and 10 mg/L inhibiting it.
  • The research showed that different concentrations of ammonia nitrogen can affect the digestive activity of juvenile yellowfin tuna, with significant increases in interleukin 6 receptor (IL-6r) levels and marked reductions in interleukin 10 (IL-10) levels.
  • The study provides a scientific foundation for the recirculating water culture of juvenile yellowfin tuna and helps to promote the development of its aquaculture industry.

Statistics:

  • Ammonia concentrations of 5 mg/L inhibited liver amylase (AMS) and lipase (LPS) after 24 h, resulting in a 50% reduction in LPS activity.
  • Ammonia concentrations of 10 mg/L inhibited LPS activity in the foregut by 70% compared to the control group.
  • Ammonia concentrations of 5 mg/L significantly increased relative expression of the superoxide dismutase 2 (SOD2) gene by 150% at 6 and 24 h.
  • Ammonia concentrations of 10 mg/L significantly increased interleukin 6 receptor (IL-6r) levels by 300% compared to the control group.

Sources:

  • Mechanism of digestion enzymes and related genes in response to acute ammonia-nitrogen stress in juvenile yellowfin tuna (Thunnus albacares). Marine Environmental Research, 2025;209:107165.
  • Zhengyi Fu, Yongyue Sun, and Zhenhua Ma. Marine Environmental Research, 2025;209:107165.