Tiny Fossils-Big Data: microplankton and their ecology in the climate system

中生代海洋革命将海洋中碳酸盐的保存地点从大陆架转移到深海，从而稳定了地球的气候。这种转变在很大程度上是由于两类不同的微型浮游生物--钙质超微化石和浮游有孔虫。这些类群将大量的碳固定在海底；今天，近40%的海底被来自这些分类群的钙质淤泥覆盖。其他重要的基团主要生产硅质材料。异养浮游有孔虫产生碳酸盐测试，异养放射虫分泌硅质测试，钙质超微化石(包括球藻)是自养生物，自养硅藻产生硅质小树枝。由于这些生物形成了海底的大部分沉积物，它们的演化与海洋沉积记录之间存在联系。它们的进化受生物(例如，依赖多样性)和非生物(气候和海洋学)因素的混合控制。然而，在我们对这些因素和这些群体的演变之间的联系的理解上存在差距。例如，方解石补偿深度(CCD)，即碳酸盐(CaCO3)被保存并因此储存二氧化碳的深度，是海相碳酸盐循环中最重要的单一阈值。它被认为是由全球气候、地球化学循环(例如，大陆的风化)、钙质浮游生物生产力、海平面和环流决定的。尽管有证据表明，当地的CaCO3通量影响了CCD值，但在讨论过去的CCD值波动时，通常不包括生态或进化变化。气候和生物地球化学模型通常忽略了浮游微生物的关键方面：它们的进化、生态、丰度、季节性生产力或通量，甚至它们的壳或壳的大小。我的小组将解决这个关键问题：浮游生物生态如何影响远洋碳酸盐和硅质生产动态？这四个主要的矿化微化石群提供了一个很好的实验装置。对它们的联合研究使我们能够检验不同类群之间的差异成功，它们的演变，以及它们对气候和海洋沉积物的影响(S)。在文献中，除了孤立地研究这些群体之外，很少研究这些群体。即使当它们被放在一起研究时，它们的空间分布、种群动态、季节性或它们作为沉积物生产者的作用通常是单独研究的--我们只考虑每一组的宏观进化成功。这项研究计划将通过利用新的合成数据汇编的新方法来解决这些弱点。这项研究计划将使用一个整体的方法来研究这些生物在过去2亿年中的生态成功和空间格局。

The Mesozoic marine revolution stabilized Earth's climate by shifting the locus of carbonate preservation in the ocean from continental shelves to the deep-sea. The shift was largely due to the two different groups of microplankton, calcareous nannofossils and the planktic foraminifera. These groups sequester carbon on the seafloor in substantial amounts; nearly 40% of the seafloor today is covered by calcareous ooze derived from these taxa. Other important groups primarily produce siliceous material. The heterotrophic planktic foraminifera produce carbonate tests, heterotrophic radiolarians secrete siliceous tests, the calcareous nannofossils (inc. coccolithophorids) are autotrophs, and the autotrophic diatoms produce siliceous frustules. Because these organisms form much of the sediment on the seafloor, there is a connection between their evolution and the marine sedimentary record. Their evolution is controlled by a mix of biotic (e.g., diversity dependence) and abiotic (climate and oceanography) factors. There are, however, gaps in our understanding of the connections between these factors and the evolution of these groups. For example, the calcite compensation depth (CCD), the depth above which carbonate (CaCO3) is preserved and thus CO2 stored, is the most important single threshold in the marine carbonate cycle. It is thought to be governed by global climate, geochemical cycles (e.g., weathering of the continents), calcareous plankton productivity, sea level, and circulation. Ecological or evolutionary changes are generally not included when discussing past CCD fluctuations, despite evidence that local CaCO3 flux influences the CCD. Climate and biogeochemical models generally ignore key aspects of pelagic microorganisms: their evolution, ecology, abundances, seasonal productivity or flux, or even the size of their shells or liths. My group will address this key question: How does plankton ecology affect pelagic carbonate and siliceous production dynamics? The four main mineralized microfossil groups provide an excellent experimental set up. Studying them in tandem allows us to examine the differential success among the different groups, their evolution, and the impact(s) they have on climate and marine sediments. Within the literature, it is rare to examine these groups other than in isolation. Even when they are examined together, typically their spatial distribution, population dynamics, seasonality, or their role as sediment producers are studied in isolation - we only think of each groups' macroevolutionary success. This research program will address these weaknesses by using novel approaches utilizing a new synthetic data compilation. This program of study will use a holistic approach to look at the ecological success and spatial patterns of these organisms over the past 200 million years.