Department of Oceanography, Federal University of Pernambuco (UFPE), Recife, PE, Brazil.
Oceanographic Institute at the University of São Paulo (IO-USP), São Paulo, SP, Brazil.
Geobiology. 2021 Jan;19(1):63-74. doi: 10.1111/gbi.12414. Epub 2020 Sep 15.
Coccolithophores are a key functional phytoplankton group and produce minute calcite plates (coccoliths) in the sunlit layer of the pelagic ocean. Coccoliths significantly contribute to the sediment record since the Triassic and their geometry have been subject to palaeoceanographic and biological studies to retrieve information on past environmental conditions. Here, we present a comprehensive analysis of coccolith, coccosphere and cell volume data of the Southern Ocean Emiliania huxleyi ecotype A, subject to gradients of temperature, irradiance, carbonate chemistry and macronutrient limitation. All tested environmental drivers significantly affect coccosphere, coccolith and cell volume with driver-specific sensitivities. However, a highly significant correlation emerged between cell and coccolith volume with V = 0.012 ± 0.001 * V + 0.234 ± 0.066 (n = 23, r = .85, p < .0001, σ = 0.127), indicating a primary control of coccolith volume by physiological modulated changes in cell volume. We discuss the possible application of fossil coccolith volume as an indicator for cell volume/size and growth rate and, additionally, illustrate that macronutrient limitation of phosphorus and nitrogen has the predominant influence on coccolith volume in respect to other environmental drivers. Our results provide a solid basis for the application of coccolith volume and geometry as a palaeo-proxy and shed light on the underlying physiological reasons, offering a valuable tool to investigate the fossil record of the coccolithophore E. huxleyi.
颗石藻是一种关键的功能浮游植物群，在海洋的光照层中产生微小的方解石板（颗石）。自三叠纪以来，颗石显著地贡献了沉积物记录，其几何形状已经成为古海洋学和生物学研究的主题，以获取过去环境条件的信息。在这里，我们对南大洋 Emiliania huxleyi 生态型 A 的颗石、颗石球和细胞体积数据进行了全面分析，这些数据受到温度、光照、碳酸盐化学和大量营养物质限制的梯度影响。所有测试的环境驱动因素都显著影响颗石球、颗石和细胞体积，具有特定的驱动敏感性。然而，细胞和颗石体积之间出现了高度显著的相关性，V = 0.012 ± 0.001 * V + 0.234 ± 0.066（n = 23，r =.85，p <.0001，σ = 0.127），表明颗石体积主要受到细胞体积变化的生理调节控制。我们讨论了将化石颗石体积作为细胞体积/大小和生长率的指标的可能应用，并进一步说明磷和氮的大量营养物质限制对颗石体积的影响超过其他环境驱动因素。我们的结果为颗石体积和几何形状作为古代理化指标的应用提供了坚实的基础，并阐明了潜在的生理原因，为研究化石记录中的 Emiliania huxleyi 颗石藻提供了有价值的工具。
