The combined effect of temperature and pH on embryonic development of obscure puffer Takifugu obscurus and its ecological implications

• Time to 50% hatch was significantly shortened with increase in temperature.
• Time to 50% hatch was significantly delayed at pH 5 than at pH 6–8.
• Significant interaction was detected between temperature and pH on incubation time.
• Both high temperature and low pH negatively affected hatch success.
• No significant interaction was found between temperature and pH on hatch success.

Rising temperature and decreasing pH caused by climate change may affect the development of fish. The objective of this study was to determine the combined effects of temperature (19, 22, 25, 28 °C) and pH (5, 6, 7, 8) on incubation time, total hatch rate, abnormal rate, and viability of newly hatched larvae 24 h post-hatch of obscure puffer Takifugu obscurus fertilized eggs. The results showed that incubation time was significantly shortened with increase in temperature and delayed at low pH. Significant interaction was detected between temperature and pH on incubation time. Both temperature and pH significantly affected the total hatch rate, abnormal rate, and the viability of newly hatched larvae, but no significant interaction was detected. Such results indicated that fluctuations in temperature and decreasing pH in waters during the spawning season of this anadromous species may have substantially negative impacts on its population recruitment and persistence.