Influence of salinity on juvenile obscure puffer Takifugu obscures

摘要

ABSTRACT Salinity tolerance of juvenile obscure puffer Takifuge obscurus was investigated at salinities of 0, 8, 16, 24 and 32 parts per thousand (ppt). In consequence, the juveniles of obscure puffer were able to survive and grow well at salinities from freshwater (0?￠????ppt) to 32?￠????ppt. In addition, the effects of salinity on serum osmolality, morphology of chloride cells in gill filaments, and branchial NKT (Na + /K + -ATPase) activity and expression were also assessed. At the beginning of the trial (day 15), the serum osmolality, NKT activity and expression in fish reared at salinities all increased, followed by decreases in serum osmolality and NKT activity, and slight change in NKT expression. Besides, the chloride cells became larger and denser with increasing salinity at the end of the trial. Our results demonstrate that the juveniles can osmoregulate in a wide range of salinity and provide indirect evidence that chloride cells and NKT in gill are responsible for excretion of excess salt from body in hyperosmotic environments. The ability for juvenile obscure puffer to maintain homeostasis and grow well in a wide range of salinities, from 0 to 32?￠????ppt, supports the hypothesis that the juveniles of obscure puffer are suitable for both freshwater and seawater aquaculture.