School of Biological Sciences, University of Essex, Colchester, UK.
Glob Chang Biol. 2013 Apr;19(4):1007-16. doi: 10.1111/gcb.12105. Epub 2013 Jan 18.
The production of the marine trace gas dimethyl sulfide (DMS) provides 90% of the marine biogenic sulfur in the atmosphere where it affects cloud formation and climate. The effects of increasing anthropogenic CO2 and the resulting warming and ocean acidification on trace gas production in the oceans are poorly understood. Here we report the first measurements of DMS-production and data on growth, DMSP and DMS concentrations in pH-stated cultures of the phytoplankton haptophyte Emiliania huxleyi. Four different environmental conditions were tested: ambient, elevated CO2 (+CO2 ), elevated temperature (+T) and elevated temperature and CO2 (+TCO2 ). In comparison to the ambient treatment, average DMS production was about 50% lower in the +CO2 treatment. Importantly, temperature had a strong effect on DMS production and the impacts outweighed the effects of a decrease in pH. As a result, the +T and +TCO2 treatments showed significantly higher DMS production of 36.2 ± 2.58 and 31.5 ± 4.66 μmol L(-1) cell volume (CV) h(-1) in comparison with the +CO2 treatment (14.9 ± 4.20 μmol L(-1) CV h(-1) ). As the cultures were aerated with an air/CO2 mixture, DMS was effectively removed from the incubation bottles so that concentration remained relatively low (3.6-6.1 mmol L(-1) CV). Intracellular DMSP has been shown to increase in E. huxleyi as a result of elevated temperature and/or elevated CO2 and our results are in agreement with this finding: the ambient and +CO2 treatments showed 125 ± 20.4 and 162 ± 27.7 mmol L(-1) CV, whereas +T and +TCO2 showed significantly increased intracellular DMSP concentrations of 195 ± 15.8 and 211 ± 28.2 mmol L(-1) CV respectively. Growth was unaffected by the treatments, but cell diameter decreased significantly under elevated temperature. These results indicate that DMS production is sensitive to CO2 and temperature in E. huxleyi. Hence, global environmental change that manifests in ocean acidification and warming may not result in decreased DMS as suggested by earlier studies investigating the effect of elevated CO2 in isolation.
海洋痕量气体二甲基硫（DMS）的产生提供了大气中 90%的海洋生源硫，它影响云的形成和气候。人们对不断增加的人为 CO2 以及由此产生的变暖与海洋酸化对海洋中痕量气体产生的影响知之甚少。本文首次报道了在 pH 值设定的海洋浮游植物甲藻哈氏藻培养物中 DMS 产生的测量值和数据，以及 DMSP 和 DMS 浓度。测试了四种不同的环境条件：自然条件、高 CO2（+CO2）、高温（+T）和高温与 CO2（+TCO2）。与自然处理相比，+CO2 处理中 DMS 的平均产生量约低 50%。重要的是，温度对 DMS 的产生有很强的影响，其影响超过了 pH 值降低的影响。结果，+T 和 +TCO2 处理的 DMS 产生量明显更高，分别为 36.2±2.58 和 31.5±4.66 μmol L-1 细胞体积（CV）h-1，而+CO2 处理为 14.9±4.20 μmol L-1 CV h-1。由于培养物用空气/CO2 混合物通气，DMS 从孵育瓶中有效去除，因此浓度保持相对较低（3.6-6.1 mmol L-1 CV）。已经证明，在甲藻中，由于温度升高和/或 CO2 升高，细胞内 DMSP 增加，我们的结果与这一发现一致：自然和+CO2 处理的细胞内 DMSP 浓度分别为 125±20.4 和 162±27.7 mmol L-1 CV，而+T 和+TCO2 处理的细胞内 DMSP 浓度则显著升高，分别为 195±15.8 和 211±28.2 mmol L-1 CV。处理对生长没有影响，但在高温下细胞直径显著减小。这些结果表明，在甲藻中，DMS 的产生对 CO2 和温度敏感。因此，与早期研究孤立地研究升高的 CO2 的影响相比，全球环境变化表现为海洋酸化和变暖，可能不会导致 DMS 的减少。
