School of Life Sciences, University of Essex, Colchester, UK.
Department of Mathematical Sciences, University of Essex, Colchester, UK.
Glob Chang Biol. 2020 Nov;26(11):6445-6456. doi: 10.1111/gcb.15324. Epub 2020 Sep 18.
Estimates of marine N fixation range from 52 to 73 Tg N/year, of which we calculate up to 84% is from Trichodesmium based on previous measurements of nifH gene abundance and our new model of Trichodesmium growth. Here, we assess the likely effects of four major climate change-related abiotic factors on the spatiotemporal distribution and growth potential of Trichodesmium for the last glacial maximum (LGM), the present (2006-2015) and the end of this century (2100) by mapping our model of Trichodesmium growth onto inferred global surface ocean fields of pCO , temperature, light and Fe. We conclude that growth rate was severely limited by low pCO at the LGM, that current pCO levels do not significantly limit Trichodesmium growth and thus, the potential for enhanced growth from future increases in CO is small. We also found that the area of the ocean where sea surface temperatures (SST) are within Trichodesmium's thermal niche increased by 32% from the LGM to present, but further increases in SST due to continued global warming will reduce this area by 9%. However, the range reduction at the equator is likely to be offset by enhanced growth associated with expansion of regions with optimal or near optimal Fe and light availability. Between now and 2100, the ocean area of optimal SST and irradiance is projected to increase by 7%, and the ocean area of optimal SST, irradiance and iron is projected to increase by 173%. Given the major contribution of this keystone species to annual N fixation and thus pelagic ecology, biogeochemistry and CO sequestration, the projected increase in the geographical range for optimal growth could provide a negative feedback to increasing atmospheric CO concentrations.
海洋固氮的估计范围为 52 至 73 Tg N/年，我们根据之前对 nifH 基因丰度的测量和我们对 Trichodesmium 生长的新模型，计算出其中高达 84%来自 Trichodesmium。在这里，我们通过将我们的 Trichodesmium 生长模型映射到推断出的全球表层海洋 pCO2、温度、光照和 Fe 场，评估了四个与气候变化相关的主要非生物因素对 Trichodesmium 时空分布和生长潜力的可能影响。在上个冰河时代（LGM）、现在（2006-2015 年）和本世纪末（2100 年）。我们的结论是，LGM 时低 pCO2 严重限制了生长速率，当前的 pCO2 水平不会显著限制 Trichodesmium 的生长，因此，未来 CO2 增加带来的潜在生长增加很小。我们还发现，从 LGM 到现在，海洋表层温度（SST）在 Trichodesmium 热区范围内的面积增加了 32%，但由于全球变暖的持续，SST 的进一步增加将使这一面积减少 9%。然而，赤道地区的范围缩小可能会被与铁和光可用性最佳或接近最佳的区域扩张相关的增强生长所抵消。在现在到 2100 年之间，最佳 SST 和辐照度的海洋面积预计将增加 7%，而最佳 SST、辐照度和铁的海洋面积预计将增加 173%。鉴于该关键物种对每年固氮以及浮游生态学、生物地球化学和 CO2 封存的重大贡献，最佳生长地理范围的预计增加可能会对大气 CO2 浓度的增加产生负反馈。
