A tale of two eras: Phytoplankton composition influenced by oceanic paleochemistry
A tale of two eras: Phytoplankton composition influenced by oceanic paleochemistry
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DOI：
10.1111/gbi.12290
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发表时间：
2018-09-01
期刊：
影响因子：
3.7
通讯作者：
Knoll, Andrew H.
中科院分区：
文献类型：
--
作者：
Giordano, Mario;Olivieri, Camilla;Knoll, Andrew H.
我们报告的结果，简单的实验，支持的假设，海洋化学的变化开始在中生代导致增加营养质量每摩尔的C和每细胞的浮游藻类生物量相比，早期的浮游植物。我们培养了蓝藻，硅藻，甲藻，和绿色藻在媒体模仿古生代和中生代-新生代海洋的化学方面。在古生代和中生代-新生代生长机制之间，藻类生物量的质量出现了实质性差异;这些差异受到种间相互作用的强烈影响（即，不同物种的共存改变了对介质化学性质的响应）。这种变化是在一个中新生代的生物量的方向丰富的蛋白质每摩尔碳，虽然细胞含有较少的碳整体。这将导致较低的C：N比。假设中新生代食草动物对总碳的同化作用与早期食草动物相似，则它们的食物在化学计量上更接近其C：N需要量。这一点，沿着大陆架浮游植物平均细胞大小的增加，可能有助于促进观察到的中生代海洋动物群的进化变化。反过来，增加放牧压力将作为一个选择性的力量，更好地配备了抗放牧能力（广义），广泛发现在浮游植物与生物矿化的浮游植物分支的辐射。我们的研究结果强调了海水化学变化，增加捕食压力和上升到生态优势的叶绿素a+c藻类在中生代海洋之间的潜在联系。实验还表明，海洋化学在海洋营养结构的变化从古生代到中生代晚期的潜在作用。
We report the results of simple experiments which support the hypothesis that changes in ocean chemistry beginning in the Mesozoic Era resulted in an increase in the nutritional quality per mole of C and per cell of planktonic algal biomass compared to earlier phytoplankton. We cultured a cyanobacterium, a diatom, a dinoflagellate, and a green alga in media mimicking aspects of the chemistry of Palaeozoic and Mesozoic-Cenozoic oceans. Substantial differences emerged in the quality of algal biomass between the Palaeozoic and Mesozoic-Cenozoic growth regimes; these differences were strongly affected by interspecific interactions (i.e., the co-existence of different species alters responses to the chemistry of the medium). The change was in the direction of a Mesozoic-Cenozoic biomass enriched in protein per mole C, although cells contained less carbon overall. This would lead to a lower C:N ratio. On the assumption that Mesozoic-Cenozoic grazers' assimilation of total C was similar to that of their earlier counterparts, their diet would be stoichiometrically closer to their C:N requirement. This, along with an increase in mean cell size among continental shelf phytoplankton, could have helped to facilitate observed evolutionary changes in the Mesozoic marine fauna. In turn, increased grazing pressure would have operated as a selective force for the radiation of phytoplankton clades better equipped with antigrazing capabilities (sensu lato), as found widely in phytoplankton with biomineralization. Our results emphasize potential links between changing seawater chemistry, increased predation pressure and the rise to ecological dominance of chlorophyll a+c algae in Mesozoic oceans. The experiments also suggest a potential role for ocean chemistry in changes of marine trophic structure from the Palaeozoic to the later Mesozoic Era.