奥陶纪生物大辐射作为地质历史时期最显著的生物辐射事件之一, 其启动机制始终是生物演化与古生物学领域的核心科学问题, 藻类演化与生物辐射启动的耦合关系并非局限于大气—大洋氧化作用这一单一过程, 其在维系生态系统稳定性方面扮演关键角色。作为生态系统食物链的初级生产者, 藻类对早奥陶世生物辐射早期阶段表现出差异化响应模式, 同时亦是解析古环境演变的重要生物学载体。为系统阐释藻类在生物辐射过程中的作用机制, 本文选取华南地区混积陆棚相将军岭剖面、浅水台地相观音桥剖面及黄花场剖面为研究对象, 通过生物碎屑定量统计与藻类分类学系统分析, 揭示出华南地区不同沉积环境背景下藻类辐射具有相对一致性的演化规律。研究共鉴定藻类3门5属, 包括蓝藻门葛万藻属、努亚藻属、波托马藻属, 绿藻门仙掌藻属及红藻门石植藻属。不同藻类的演替序列印证了大洋氧含量逐步攀升至较高水平, 为红藻等大型耗氧藻类的繁盛提供必要条件。多剖面对比研究表明, 在大洋富氧过程完成后, 藻类率先发生辐射效应, 当其生物量积累至阈值水平时, 可通过食物链传递为其他生物类群的辐射提供充足物质能量支撑, 进而驱动早奥陶世生物辐射事件的快速演进。基于黄花场剖面生物碎屑的统计数据, 对三叶虫、双壳类、腕足动物、苔藓虫及藻类的生物量变化趋势分析显示: 弗洛末期各类生物数量变化趋于稳定, 生态系统结构趋于完整, 这一特征标志着奥陶纪生物辐射第一幕的终结。该结果为生物辐射事件的幕次划分提供了新的方法论思路——即通过不同门类生物碎屑的定量统计数据, 结合其数量动态变化特征, 可作为生物事件幕次划分的辅助判别依据。

The Great Ordovician Biodiversification Event (GOBE) ranks among the most significant bioradiation events in geological history. Algal evolution played a pivotal role in this radiation, extending beyond atmospheric and oceanic oxygenation to encompass critical functions in maintaining ecological stability. However, research on the role of algal changes during the early stages of this event remains relatively scarce. As primary producers within ecosystems, algae exhibit diverse response mechanisms to the onset of the GOBE and serve as robust indicators of paleoenvironmental shifts. To investigate the role of algae in the early stages of the GOBE, this study examines three sections in South China: the Jiangjunling section, deposited in a mixed shelf environment; and the Guanyinqiao and Huanghuachang sections, both formed in shallow-water settings. Through biomass comparisons, algal taxonomic identification, and sedimentary environment analysis, we confirm the relative consistency of algal radiation across different environments in South China. A total of three phyla and five genera of algae are identified, including Cyanophyta (Girvanella, Nuia, and Botomaella), Chlorophyta (Halimeda), and Rhodophyta (Petrophyton). The evolutionary succession of these algal groups indicates a sustained decrease in temperature and a gradual increase in oceanic oxygen levels from the Tremadocian to the Floian, consistent with findings from previous studies. Comparisons among sections reveal that algae underwent radiation prior to other taxa following oceanic oxygenation. Once reaching a critical abundance threshold, they established a sufficient material and energy foundation, thereby driving the rapid diversification of other organisms. Analysis of biomass trends of the Huanghuachang section—including trilobites, bivalves, brachiopods, bryozoans, and algae—demonstrates that interspecific equilibrium was achieved, and that the ecosystem as a whole became structurally complete by the end of the Floian. This milestone marks the culmination of the first episode of the GOBE. The results offer a novel methodological approach: statistics of biomass of diverse taxa, combined with analyses of interspecific balance, can serve as a reliable basis for subdividing biological events.

国家自然科学基金项目(41702113)资助