| Abstract: | The objective of this study was to investigate the effects of ammonia nitrogen on the embryonic development of the cuttlefish Sepia pharaonis . Embryos were exposed to different concentrations (0, 1, 3, and 5 mg/L) of total ammonia–nitrogen (TAN) during incubation. The developmental rate, malformations, mortality, hatching rate, incubation period, yolk utilization efficiency ratio, and weight of the newly hatched cuttlefish were determined. The results showed that ammonia nitrogen significantly inhibited the development of S. pharaonis embryos and induced malformations and even death. Hatching was delayed, the hatching rate was reduced, mortality and the incubation period increased, and the yolk utilization efficiency ratio and weight of the newly hatched cuttlefish significantly decreased in a dose‐dependent manner after the embryos were exposed to more than 1 mg/L TAN for prolonged period. These variables could be used as an integrative biomarker or indicator of aquatic environmental ammonia contamination. In summary, our results indicated that ammonia caused toxicity in the embryos. When the concentration of TAN is greater than 1 mg/L, ammonia levels should be reduced to prevent toxic effects on embryonic development. |
