Seawater carbonate chemistry and processes during experiments with seaurchins Hemicentrotus pulcherrimus and Echinometra mathaei, 2004

Increased carbon dioxide (CO2) concentration in the atmosphere will change the balance of the components of carbonate chemistry and reduce the pH at the ocean surface. Here, we report the effects of increased CO2 concentration on the early development of the sea urchins Hemicentrotus pulcherrimus and Echinometra mathaei. We examined the fertilization, early cleavage, and pluteus larval stage to evaluate the impact of elevated CO2 concentration on fertilization rate, cleavage rate, developmental speed, and pluteus larval morphology. Furthermore, we compared the effects of CO2 and HCl at the same pH in an attempt to elucidate any differences between the two. We found that fertilization rate, cleavage rate, developmental speed, and pluteus larval size all tended to decrease with increasing CO2 concentration. Furthermore, CO2-seawater had a more severe effect than HCl-seawater on the fertilization rate. By contrast, the effects on cleavage rate, developmental speed, and pluteus larval morphology were similar for CO2- and HCl-seawater. Our results suggest that both decreased pH and altered carbonate chemistry affect the early development and life history of marine animals, implying that increased seawater CO2 concentration will seriously alter marine ecosystems. The effects of CO2 itself on marine organisms therefore requires further clarification.

大气中二氧化碳（CO₂）浓度升高会改变碳酸盐化学成分的平衡，并降低海洋表层pH值。本文报道了CO₂浓度升高对海胆Hemicentrotus pulcherrimus和Echinometra mathaei早期发育的影响。我们通过检测受精、早期卵裂及长腕幼虫阶段，评估了CO₂浓度升高对受精率、卵裂率、发育速度及长腕幼虫形态的影响。此外，我们比较了相同pH条件下CO₂和盐酸（HCl）的作用，试图阐明两者之间的差异。研究发现，随着CO₂浓度升高，受精率、卵裂率、发育速度及长腕幼虫体型均呈下降趋势。此外，CO₂海水对受精率的影响比HCl海水更为严重。相比之下，CO₂海水与HCl海水对卵裂率、发育速度及长腕幼虫形态的影响相似。我们的结果表明，pH降低和碳酸盐化学改变均会影响海洋动物的早期发育及生活史，这意味着海水CO₂浓度升高将严重改变海洋生态系统。因此，CO₂本身对海洋生物的影响仍需进一步阐明。