Impacts of CO₂-driven seawater acidification on survival, egg production rate and hatching success of four marine copepods

Ecological experiments were conducted to examine the effects of seawater containing elevated partial pressure of carbon dioxide (p_CO2 800×10^-6, 2 000×10^-6, 5 000×10^-6 and 10 000×10^-6) on the survival and reproduction of female Acartia pacifica, Acartia spinicauda, Calanus sinicus and Centropages tenuiremis, which are the dominant copepods in the southern coastal waters of China. The results show that the effects of elevated p_CO2 on the survival rates of copepods were speciesspecific. C. sinicus, which was a macro-copepod, had a higher survival rate (62.01%-71.96%) than the other three species (5.00%-26.67%) during the eight day exposure. The egg production rates of C. sinicus, A. spinicauda and C. tenuiremis were significantly inhibited by the increased p_CO2 and the exposure time duration. There were significantly negative impacts on the egg hatching success of A. spinicauda and C. tenuiremis in the p_CO2 2 000×10^-6 and 10 000×10^-6 groups, and, in addition, the exposure time had noticeably impacts on these rates too. This study indicates that the reproductive performances of copepods were sensitive to elevated p_CO2, and that the response of different copepod species to acidified seawater was different. Furthermore, the synergistic effects of seawater acidification and climate change or other pollutant stresses on organisms should be given more attention.