Ocean acidification exacerbates the effect of UV radiation on the calcifying phytoplankter Emiliania huxleyi
Ocean acidification exacerbates the effect of UV radiation on the calcifying phytoplankter Emiliania huxleyi
复制标题
海洋酸化加剧了紫外线辐射对钙化浮游植物艾米利亚赫胥黎的影响
DOI：
10.4319/lo.2009.54.6.1855
复制
发表时间：
2009-11-01
影响因子：
4.5
通讯作者：
Helbling, E. Walter
中科院分区：
文献类型：
--
作者：
Gao, Kunshan;Ruan, Zuoxi;Helbling, E. Walter
大气中二氧化碳浓度的增加会影响大多数浮游钙化生物的钙化。高二氧化碳条件下钙化的减少或刺激在广泛分布的球石虫Emily huxleyi中都有报道。这可能通过改变球孢子层的厚度来影响细胞对光合作用有效辐射(PAR；400-700 nm)和紫外线(UVR；280-400 nm)的响应。在没有UVR的情况下，在较低的pH水平下(PHNBS分别为7.9和7.6；PCO2分别为81和178Pa或804和1759ppmv)，湖北龙须草的钙化速率降低，导致球粒石层变薄，而光合作用的碳固定在pH 7.9时略有增加，但在pH 7.6时保持不变。然而，除了PAR(88.5Wm-2)外，UVR(UV-A 19.5Wm-2，UV-B0.67Wm-2)对光合作用和钙化都有显著的抑制作用，并且随着酸化程度的增加，这些抑制作用进一步受到抑制。在pH值为7.9和7.6时，紫外线辐射和海水酸化的共同作用分别使钙化速率和光合作用的抑制率分别下降了96%和99%和6%和15%。这种对钙化和光合作用的不同抑制导致钙化与光合作用的比率显著降低。海水酸化通过球石层减少了31%，使有害紫外线的传播增加了约26%。我们的数据表明，高二氧化碳和低pH海洋对赫克斯莱伊的影响(因为与碳酸盐系统的变化相关的钙化减少)增强了UVR对主要远洋钙化生物的有害影响。
Increasing atmospheric CO2 concentration affects calcification in most planktonic calcifiers. Both reduced or stimulated calcification under high CO2 have been reported in the widespread coccolithophore Emiliania huxleyi. This might affect the response of cells to photosynthetically active radiation (PAR; 400‐700 nm) and ultraviolet radiation (UVR; 280‐400 nm) by altering the thickness of the coccolith layer. Here we show that in the absence of UVR, the calcification rates in E. huxleyi decrease under lowered pH levels (pHNBS of 7.9 and 7.6; pCO2 of 81 and 178 Pa or 804 and 1759 ppmv, respectively) leading to thinned coccolith layers, whereas photosynthetic carbon fixation was slightly enhanced at pH 7.9 but remained unaffected at pH 7.6. Exposure to UVR (UV‐A 19.5 W m‐2, UV‐B 0.67 W m‐2) in addition to PAR (88.5 W m‐2), however, results in significant inhibition of both photosynthesis and calcification, and these rates are further inhibited with increasing acidification. The combined effects of UVR and seawater acidification resulted in the inhibition of calcification rates by 96% and 99% and that of photosynthesis by 6% and 15%, at pH 7.9 and 7.6, respectively. This differential inhibition of calcification and photosynthesis leads to significant reduction of the ratio of calcification to photosynthesis. Seawater acidification enhanced the transmission of harmful UVR by about 26% through a reduction of the coccolith layer of 31%. Our data indicate that the effect of a high‐CO2 and low‐pH ocean on E. huxleyi (because of reduced calcification associated with changes in the carbonate system) enhances the detrimental effects of UVR on the main pelagic calcifier.