Effects of seawater acidification on early development of the sea urchin Hemicentrotus pulcherrimus

To explore the impact of CO 2 -induced seawater acidification on benthic echinoderms, Hemicentrotus pulcherrimus inhabiting intertidal coastal zone in north China was utilized to evaluate the effects of seawater acidification on fertilization, embryogenesis and early larval development. Based on the projection of IPCC, present natural seawater condition (pH = 8.06 ± 0.01) and three laboratory-controlled acidified conditions (OA 1 , ΔpH = −0.3 units; OA 2 , ΔpH = −0.4 units; OA 3 , ΔpH = −0.5 units) were set up. Results showed that: (1) seawater acidification had no effect on fertilization; (2) early embryonic cleavage tended to be delayed and the proportion of aberrant cleavage increased in a dose-dependent manner with decreased pH; (3) the hatching rate of blastulae and larvae survival rate were both decreased with pH decline; and (4) larval abnormalities including impaired symmetry, elongated skeletal elements and corroded spicules were observed in all OA treatments as compared to control. All data observed in this study support the concern that the response of echinoderms to seawater acidification varies among species, and further research is required to clarify the specific cellular mechanisms involved.