Are foraminifera what they eat?

他们吃的是有孔虫吗？

• 批准号: NE/K00087X/1
• 负责人: Babette Hoogakker
• 金额: $ 5.3万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FK00087X%2F1
• 关键词: foraminifera; what; they; eat

In the oceans microscopic plants called phytoplankton use carbon dioxide, light and nutrients to produce organic matter, which provides the basis of the marine food-chain. The process where carbon dioxide is converted into organic matter is termed photosynthesis. The element carbon occurs on earth in three forms, with the same amount of protons, but increasing neutrons: 99% of carbon exists like carbon-12 (6 protons, 6 neutrons), ~1% as carbon-13 (6 protons, 7 neutrons), and a minute fraction of carbon-14 (6 protons, 8 neutrons). Plants actively discriminate against the heavier carbon-13 during photosynthesis (it is easier to incorporate the smaller atom) causing relative enrichment in carbon-12. Comparison of the ratio of carbon-13 over carbon-12 (=carbon isotope) of the carbon in carbon dioxide and that of organic matter provides a measure of fractionation. Within the Atlantic Ocean the carbon isotope ratio of phytoplankton generally tracks productivity, with phytoplankton from high productivity regions having considerably higher carbon isotopic ratios compared with low productivity regions. If we could measure phytoplankton organic carbon isotopes on geological samples we might be able to obtain information of past productivity changes in the area. The problem is that (1) many of the proteins that form the organic material may degrade after burial in sediments, (2) the organic material extracted from bulk sediments (it is not possible to just extract organic material from phytoplankton material) may be sourced from several other sources (including terrestrial plants, or old material carried by a deep sea current from somewhere else), and so may not represent actual surface water conditions. This research proposal will test whether planktonic foraminifera (zooplankton that live near the sea surface and eats phytoplankton) organic carbon isotopes also track productivity, to assess it's application for historical reconstructions of marine productivity.

在海洋中，被称为浮游植物的微小植物利用二氧化碳、光和营养物质来产生有机物质，有机物质为海洋食物链提供了基础。二氧化碳转化为有机物的过程称为光合作用。碳元素在地球上以三种形式存在，质子数量相同，但中子数量增加：99%的碳以碳12（6个质子，6个中子）的形式存在，约1%的碳以碳13（6个质子，7个中子）的形式存在，还有一小部分碳14（6个质子，8个中子）。植物在光合作用过程中积极地排斥较重的碳-13（更容易结合较小的原子），导致碳-12相对富集。比较二氧化碳中碳的碳13与碳12（=碳同位素）的比率和有机物中的碳13与碳12的碳同位素的比率提供了分馏的量度。在大西洋内，浮游植物的碳同位素比率通常追踪生产力，与低生产力区域相比，高生产力区域的浮游植物具有相当高的碳同位素比率。如果我们能测量地质样品中浮游植物的有机碳同位素，我们也许能够获得该地区过去生产力变化的信息。问题在于：（1）许多形成有机物质的蛋白质在被沉积物掩埋后可能会降解，（2）从大量沉积物中提取的有机物质（不可能只从浮游植物中提取有机物质）可能来自其他几个来源（包括陆地植物，或由深海水流从其他地方携带的旧物质），因此可能不代表实际的地表水条件。这项研究计划将测试浮游有孔虫（生活在海面附近并以浮游植物为食的浮游动物）的有机碳同位素是否也能追踪生产力，以评估其在海洋生产力历史重建中的应用。