Responses of Takifugu obscurus fertilized eggs and larvae to increased ammonia exposure
2015
Wang, Jun | Li, Jiajia | Xu, Nuo | Li, Jing | Li, Ziheng | Chen, Yafen | Yang, Zhou
Ammonia is a common toxicant in aquatic systems; this substance has become a critical threat to fish, especially in early life stages. This study aimed to evaluate the effects of unionized ammonia (NH₃-N: 0, 0.068, 0.138, 0.206, 0.275, 0.343, 0.412, and 0.481 mg L⁻¹) on fertilized eggs and larvae of obscure puffer Takifugu obscurus, a fish species with potential economic value. Results showed that hatch time was significantly retarded and hatch rate was significantly decreased as NH₃-N concentrations increased; newly hatched larvae exhibited high rate of abnormalities and low viability. The survival rate of larvae also decreased significantly as NH₃-N concentrations increased; larvae could tolerate NH₃-N to a less extent than embryos. NH₃-N also caused a significant decrease in superoxide dismutase (SOD) and Na⁺/K⁺ ATPase activities but not in malondialdehyde (MDA) levels of larvae. Two-way ANOVA indicated that there was a statistically significant interaction between NH₃-N concentrations and exposure times on SOD activity but not on Na⁺/K⁺ ATPase activity. Such responses indicated that an increase in ammonia concentration in surface water may negatively affect the early development of T. obscurus and thus likely impair population recruitment and persistence of this fish species.
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