Biogeochemical implications of comparative growth rates of Emiliania huxleyi and Coccolithus species
Biogeochemical implications of comparative growth rates of Emiliania huxleyi and Coccolithus species
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DOI：
10.5194/bg-11-6915-2014
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发表时间：
2014-01-01
期刊：
影响因子：
4.9
通讯作者：
Poulton, A. J.
中科院分区：
文献类型：
--
作者：
Daniels, C. J.;Sheward, R. M.;Poulton, A. J.
颗石藻是一种多样的浮游植物，对远洋方解石的生产和出口做出了重要贡献，但除了无处不在的Emiliania huxleyi外，其他物种的比较地球化学作用还知之甚少。不同颗石藻种对方解石总产量的贡献受混合群落中细胞方解石、生长速率和相对丰度的种间差异控制。在这项研究中，我们研究了E。huxleyi和两个Coccolithus物种在每日方解石生产方面。培养实验比较了E. huxleyi（北极和温带菌株）、Coccolithus pelagicus（新北极菌株）和Coccolithus braarudii（温带菌株）。尽管假设E. huxleyi是一种快速生长的物种，在相同的温度和光照条件下，三个物种之间的生长速率大致相当（0.16-0.85 d（-1））。Emiliania huxleyi的平均生长速度仅比C. pelagicus，比C. braarudii。C. pelagicus和C. braarudii通常比E. huxleyi，可比的增长率表明，Coccolithus物种有可能成为混合种群中的主要方解石生产者。为了进一步探索这些结果，我们设计了一个简单的模型，比较了椰子树和E. huxleyi在一个现实的相对丰度范围和一个广泛的相对增长率。利用我们的培养研究中生长率的相对差异，我们发现C。若E. huxleyi到C.浮游动物比例低于34：1。2010年春季和夏季从北大西洋野外采集的相对丰度数据表明，C. pelagicus主导方解石生产的69%的网站抽样。在生长率上有一个更极端的差异，其中C。pelagicus的生长速度是E. huxleyi，C. pelagicus仍然在14%的油田中主导方解石生产。这些结果表明，在评估不同颗石藻对远洋方解石生产的贡献时，有必要考虑种间生长速率、细胞方解石和相对丰度差异之间的相互作用。在C. pelagicus，我们发现，有很强的潜力，这个物种作出重大贡献，方解石生产在北大西洋，虽然从外地的相对增长率的估计，需要确认我们的结论。
Coccolithophores, a diverse group of phytoplankton, make important contributions to pelagic calcite production and export, yet the comparative biogeochemical role of species other than the ubiquitous Emiliania huxleyi is poorly understood. The contribution of different coccolithophore species to total calcite production is controlled by inter-species differences in cellular calcite, growth rate and relative abundance within a mixed community. In this study we examined the relative importance of E. huxleyi and two Coccolithus species in terms of daily calcite production. Culture experiments compared growth rates and cellular calcite content of E. huxleyi (Arctic and temperate strains), Coccolithus pelagicus (novel Arctic strain) and Coccolithus braarudii (temperate strain). Despite assumptions that E. huxleyi is a fast-growing species, growth rates between the three species were broadly comparable (0.16-0.85 d(-1)) under identical temperature and light conditions. Emiliania huxleyi grew only 12% faster on average than C. pelagicus, and 28% faster than C. braarudii. As the cellular calcite content of C. pelagicus and C. braarudii is typically 30-80 times greater than E. huxleyi, comparable growth rates suggest that Coccolithus species have the potential to be major calcite producers in mixed populations. To further explore these results we devised a simplistic model comparing daily calcite production from Coccolithus and E. huxleyi across a realistic range of relative abundances and a wide range of relative growth rates. Using the relative differences in growth rates from our culture studies, we found that C. pelagicus would be a larger source of calcite if abundances of E. huxleyi to C. pelagicus were below 34:1. Relative abundance data collected from North Atlantic field samples (spring and summer 2010) suggest that, with a relative growth rate of 88 %, C. pelagicus dominated calcite production at 69% of the sites sampled. With a more extreme difference in growth rates, where C. pelagicus grows at 1 / 10th of the rate of E. huxleyi, C. pelagicus still dominated calcite production in 14% of the field. These results demonstrate the necessity of considering interactions between inter-species differences in growth rates, cellular calcite and relative abundances when evaluating the contribution of different coccolithophores to pelagic calcite production. In the case of C. pelagicus, we find that there is strong potential for this species to make major contributions to calcite production in the North Atlantic, although estimates of relative growth rates from the field are needed to confirm our conclusions.