Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada.
PLoS One. 2020 Mar 27;15(3):e0230569. doi: 10.1371/journal.pone.0230569. eCollection 2020.
Different morphotypes of the abundant marine calcifying algal species Emiliania huxleyi are commonly linked to various degrees of E. huxleyi calcification, but few studies have been done to validate this assumption. This study investigated therefore whether E. huxleyi morphotypes can be related to coccolithophore calcification and coccolith mass. Samples from January (high productivity) and September (low productivity) 1997 at an open ocean and a coastal site near the Canary Islands were analysed using a combination of thickness measurements (Circular Polarizer Retardation estimates (CPR) method), Scanning Electron Microscope imaging, and Markov Chain Monte Carlo (MCMC) models. Mean E. huxleyi coccolith mass varied from a maximum of 2.9pg at the open ocean station in January to a minimum of 1.7pg in September at both stations. In contrast, overall calcite produced by E. huxleyi (assuming 23 coccoliths/cell) varied from a maximum of 2.6 μgL-1 at the coastal station in January to a minimum of 0.5 μgL-1 in September at the open ocean site. The relative abundance of "Overcalcified" Type A, Type A, Group B and malformed coccoliths was determined from SEM images. The mean coccolith mass of "Overcalcified" Type A was 2.0pg using the CPR-method, while mean mass of Type A and Group B coccoliths was determined using coccolith length measurements from SEM images and MCMC models relating thickness measurements to morphotype relative abundance. Type A cocccolith mass varied from a 1.6pg to 2.6pg and Group B coccolith mass varied from 1.5pg to 2.0pg. These results demonstrate that the coccolith mass of Type A, "Overcalcified" Type A, and Group B do not differ systematically and there is no systematic relationship between relative abundance of a morphotype and the overall calcite production of E. huxleyi. Therefore, morphotype appearance and relative abundance can not be uniformly used as reliable indicators of E. huxleyi calcification or calcite production.
丰富的海洋钙化藻类物种 Emiliania huxleyi 的不同形态通常与不同程度的 E. huxleyi 钙化有关，但很少有研究对此假设进行验证。因此，本研究调查了 E. huxleyi 形态是否可以与颗石藻钙化和颗石质量相关。1997 年 1 月（高生产力）和 9 月（低生产力）在开放海域和加那利群岛附近的沿海站点采集的样品使用厚度测量（Circular Polarizer Retardation estimates (CPR) 方法）、扫描电子显微镜成像和马尔可夫链蒙特卡罗 (MCMC) 模型的组合进行分析。最大的 2.9pg 在 1 月的开放海域站，最小的 1.7pg 在 9 月的两个站。相比之下，E. huxleyi 产生的总方解石量（假设每个细胞 23 个颗石藻）从 1 月沿海站的最大值 2.6 μgL-1 到开放海域站 9 月的最小值 0.5 μgL-1。从 SEM 图像中确定了“过度钙化”A 型、A 型、B 组和畸形颗石藻的相对丰度。使用 CPR 方法，“过度钙化”A 型的平均颗石质量为 2.0pg，而 A 型和 B 组颗石的平均质量是使用 SEM 图像中的颗石长度测量值和将厚度测量值与形态相对丰度相关的 MCMC 模型确定的。A 型颗石质量变化范围为 1.6pg 至 2.6pg，B 型颗石质量变化范围为 1.5pg 至 2.0pg。这些结果表明，A 型、“过度钙化”A 型和 B 型颗石的质量没有系统差异，形态的相对丰度与 E. huxleyi 总方解石产量之间没有系统关系。因此，形态出现和相对丰度不能统一用作 E. huxleyi 钙化或方解石产量的可靠指标。
