Seawater carbonate chemistry, nutrients, particulate carbon and growth rate of Emiliania huxleyi (AC472), Calcidiscus leptoporus (AC370) and Syracosphaera pulchra (AC418) during experiments, 2011

The response of Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler, Calcidiscus leptoporus (G. Murray et V. H. Blackman) J. Schiller, andSyracosphaera pulchra Lohmann to elevated partial pressure of carbon dioxide (pCO2) was investigated in batch cultures. We reported on the response of both haploid and diploid life stages of these three species. Growth rate, cell size, particulate inorganic carbon (PIC), and particulate organic carbon (POC) of both life stages were measured at two different pCO2 (400 and 760 parts per million [ppm]), and their organic and inorganic carbon production were calculated. The two life stages within the same species generally exhibited a similar response to elevated pCO2, the response of the haploid stage being often more pronounced than that of the diploid stage. The growth rate was consistently higher at elevated pCO2, but the response of other processes varied among species. Calcification rate of C. leptoporusand of S. pulchra did not change at elevated pCO2, whereas it increased in E. huxleyi. POC production and cell size of both life stages of S. pulchra and of the haploid stage of E. huxleyi markedly decreased at elevated pCO2. It remained unaltered in the diploid stage of E. huxleyi and C. leptoporus and increased in the haploid stage of the latter. The PIC:POC ratio increased in E. huxleyi and was constant in C. leptoporus and S. pulchra. Elevated pCO2 has a significant effect on these three coccolithophore species, the haploid stage being more sensitive. This effect must be taken into account when predicting the fate of coccolithophores in the future ocean.

本研究调查了Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler、Calcidiscus leptoporus (G. Murray et V. H. Blackman) J. Schiller和Syracosphaera pulchra Lohmann对二氧化碳部分压力升高（pCO2）的响应，该研究在批量培养中完成。我们报告了这三种物种单倍体和二倍体生命阶段的响应。在两种不同的pCO2（400和760百万分之几 [ppm]）下，测量了两个生命阶段的生长速率、细胞大小、颗粒无机碳（PIC）和颗粒有机碳（POC），并计算了它们的有机和无机碳产量。同一物种的两个生命阶段通常对升高的pCO2表现出相似的反应，其中单倍体阶段的反应通常比二倍体阶段更为显著。在升高的pCO2下，生长速率始终较高，但其他过程的变化在各物种间存在差异。C. leptoporus和S. pulchra的钙化速率在升高的pCO2下没有变化，而E. huxleyi的钙化速率则有所增加。S. pulchra和E. huxleyi单倍体阶段两个生命阶段的POC产量和细胞大小在升高的pCO2下明显降低。在E. huxleyi和C. leptoporus的二倍体阶段以及后者的单倍体阶段，这一变化保持不变，而在后者中有所增加。PIC:POC比率在E. huxleyi中增加，而在C. leptoporus和S. pulchra中保持恒定。升高的pCO2对这三种硅藻有显著影响，其中单倍体阶段更为敏感。在预测未来海洋中硅藻的命运时，必须考虑这一影响。