Effects of increased temperature and CO2 on photosynthesis, growth, and elemental ratios in marine Synechococcus and Prochlorococcus (Cyanobacteria)
Effects of increased temperature and CO2 on photosynthesis, growth, and elemental ratios in marine Synechococcus and Prochlorococcus (Cyanobacteria)
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DOI：
10.1111/j.1529-8817.2007.00355.x
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发表时间：
2007-06-01
影响因子：
2.9
通讯作者：
Hutchins, David A.
中科院分区：
文献类型：
--
作者：
Fu, Fei-Xue;Warner, Mark E.;Hutchins, David A.
人们对未来二氧化碳和温度升高对海洋微微蓝细菌生长和生理的综合影响知之甚少。我们在当前 (380 ppm) 或预测的 2100 年二氧化碳水平 (750 ppm) 下，以及在正常温度与高温 (+4°C) 下的半连续培养中培养聚球藻和原绿球藻。温度升高刺激了聚球藻的细胞分裂率，但不刺激原绿球藻的细胞分裂率。加倍的二氧化碳与升高的温度相结合，使聚球藻的最大叶绿素标准化光合速率相对于对照增加了四倍。温度还改变了聚球藻的其他光合参数（α、Phi(max)、E-k 和 Delta F/F-m'），但原绿球藻没有观察到这些变化。增加CO2 和温度都会增加聚球藻中藻胆蛋白和叶绿素a 的含量，而仅升高温度会增加原绿球藻中二乙烯基叶绿素a 的含量。随着聚球藻中 CO2 的升高，细胞碳 (C) 和氮 (N) 配额增加，但磷 (P) 配额不增加，导致 C:P 和 N:P 比率增加约 20%。相比之下，原绿球藻的元素组成仍然不受二氧化碳的影响，但细胞体积和元素配额随着温度的升高而增加一倍，同时保持恒定的化学计量。与原绿球藻相比，聚球藻对大多数测量参数的二氧化碳和温度升高的反应要大得多。我们的结果表明，全球变化可能会影响聚球藻和原绿球藻生态型的主导地位，并可能对寡营养食物网结构产生影响。然而，个别微微蓝藻菌株对未来二氧化碳和温度升高的反应可能截然不同，在概括它们对海洋全球变化的反应时需要谨慎。
Little is known about the combined impacts of future CO2 and temperature increases on the growth and physiology of marine picocyanobacteria. We incubated Synechococcus and Prochlorococcus under present-day (380 ppm) or predicted year-2100 CO2 levels (750 ppm), and under normal versus elevated temperatures (+4 degrees C) in semicontinuous cultures. Increased temperature stimulated the cell division rates of Synechococcus but not Prochlorococcus. Doubled CO2 combined with elevated temperature increased maximum chl a-normalized photosynthetic rates of Synechococcus four times relative to controls. Temperature also altered other photosynthetic parameters (alpha, Phi(max), E-k, and Delta F/F-m') in Synechococcus, but these changes were not observed for Prochlorococcus. Both increased CO2 and temperature raised the phycobilin and chl a content of Synechococcus, while only elevated temperature increased divinyl chl a in Prochlorococcus. Cellular carbon (C) and nitrogen (N) quotas, but not phosphorus (P) quotas, increased with elevated CO2 in Synechococcus, leading to similar to 20% higher C:P and N:P ratios. In contrast, Prochlorococcus elemental composition remained unaffected by CO2, but cell volume and elemental quotas doubled with increasing temperature while maintaining constant stoichiometry. Synechococcus showed a much greater response to CO2 and temperature increases for most parameters measured, compared with Prochlorococcus. Our results suggest that global change could influence the dominance of Synechococcus and Prochlorococcus ecotypes, with likely effects on oligotrophic food-web structure. However, individual picocyanobacteria strains may respond quite differently to future CO2 and temperature increases, and caution is needed when generalizing their responses to global change in the ocean.