The production and fate of fish-derived carbonate crystals in tropical shallow marine environments

热带浅海环境中鱼源碳酸盐晶体的产生和归宿

• 批准号: NE/G010617/1
• 负责人: Christopher Perry
• 金额: $ 9.23万
• 依托单位: Manchester Metropolitan University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG010617%2F1
• 关键词: production; fate; fish; derived; carbonate

A major component of the marine-atmospheric carbon cycle is the precipitation and dissolution of calcium carbonate in seawater. Calcium carbonate is the mineral that makes up rocks such as limestone and chalk. Detailed knowledge of this component is important to our understanding of the global carbon cycle, and to the earth system as a whole. This proposal aims to explore recent findings that represent a fundamental and previously unexpected change to our understanding of the marine inorganic carbon budget. Large amounts of calcium carbonate are produced in the global oceans by marine plankton and, specifically, by microscopic organisms such as coccolithophores and foraminifera. However, recent research by part of the research team here has highlighted the significant additional contribution to oceanic carbonate production by marine bony fish. These all ingest seawater and are now known to also produce calcium carbonate within their guts and excrete these precipitates at very high rates as part of their normal functioning in seawater. This previously unrecognised source of marine carbonate is significant in its own right but, when combined with new estimates of global fish biomass, it is clear that it makes a major contribution to carbonate production in particular regions of the ocean, and a smaller but significant contribution globally. Following excretion, these carbonate precipitates sink in the open oceans (along with other pelagic carbonates) and, once they reach the chemical lysoclines for carbonate (the depth at which ocean waters become undersaturated with respect to calcium carbonate), much of this material will dissolve. Thus the likely fate of these crystals in the open oceans is to dissolve at depth. In contrast, the fate of fish-derived precipitates in shallow tropical marine waters, whilst unknown, may be very different. Because fish production of calcium carbonate is positively correlated with seawater temperature, higher marine temperatures in the tropics will result in highest rates of precipitate production by fish. In addition, the shallow warm waters of tropical platform and shelf environments are typically saturated with respect to calcium carbonate, thus allowing substantial carbonate preservation and sediment accumulation to occur. Thus in these settings, with both high production rates and less potential for crystal dissolution, we hypothesise that fish-derived carbonates are making an important, but previously unrecognised, contribution to shallow water tropical carbonate sediment budgets and, especially, to the fine-grained (carbonate mud) fractions that are often volumetrically important in tropical carbonate depositional environments. It is significant to note that where attempts have been made to quantify fine-grained carbonate sediment fraction sources a significant proportion of the mud fraction remains of unknown origin (e.g. between 10 and 40% in Bahamian sediments) but is morphologically distinct from that attributable to any previously considered biogenic or inorganic source. This project will test the hypothesis that fish carbonates make up a substantial portion of this unknown fraction of carbonate mud. We will undertake an assessment of the ultrastructural and elemental characteristics of crystals that are produced by four representative shallow water tropical fish species and determine whether such crystals are contributing to carbonate sediment accumulation in these environments. If this material is indeed accumulating in these environments this would represent a previously unrecognised (and potentially volumetrically important) source for tropical shallow water carbonate sediments.

海洋 - 大气碳循环的主要组成部分是碳酸钙在海水中的沉淀和溶解。碳酸钙是构成石灰石和粉笔等岩石的矿物质。对该组件的详细了解对于我们对全球碳循环的理解以及整个地球系统很重要。该提案旨在探索最近的发现，代表了我们对海洋无机碳预算的理解的基本和意外变化。海洋浮游生物在全球海洋中产生了大量碳酸钙，具体来说是微观生物（例如coccolithophophores和foraminifera）。但是，这里研究小组的最新研究强调了海洋骨鱼对海洋碳酸盐生产的重大贡献。这些都吸收了海水，现在众所周知，它们在其肠道内产生碳酸钙，并以很高的速度排泄这些沉淀物，这是它们在海水中正常功能的一部分。以前未被认可的海洋碳酸盐来源本身具有重要意义，但是当与全球鱼类生物量的新估计结合在一起时，很明显，它对海洋特别地区的碳酸盐产量做出了重大贡献，并且在全球范围内做出了较小但重大的贡献。排泄后，这些碳酸盐会沉淀在开阔的海洋中（以及其他浮力碳酸盐），一旦它们到达化学的溶血层以碳酸盐（碳酸钙相对于碳酸钙），这些材料就会溶解。因此，这些晶体在开阔的海洋中的可能命运是在深度溶解。相比之下，在浅的热带海水中，鱼来源的降水量的命运可能会大不相同。由于碳酸钙的鱼类生产与海水温度呈正相关，因此热带地区的海洋温度较高将导致鱼类沉淀的最高生产率。另外，相对于碳酸钙，热带平台和货架环境的浅温水通常饱和，从而使大量的碳酸盐保存和沉积物的积累发生。因此，在这些情况下，既有较高的生产率又降低了晶体溶解的潜力，我们假设鱼类衍生的碳酸盐使得对浅水热带碳酸盐沉积物预算的重要副作用，尤其是对良好的（碳酸盐泥）通常在热带碳酸盐含量中大量重要的含量。值得注意的是，在尝试量化细粒碳酸盐沉积物量源的尝试中，很大一部分的泥浆含量是未知来源（例如，在巴哈马沉积物中的10％至40％之间），但在形态上与以前认为的任何生物原性或无线或无机源可归因于形态上不同。该项目将检验以下假设：鱼碳酸盐占该未知部分碳酸盐泥的很大一部分。我们将评估由四种代表性浅水热带鱼类产生的晶体的超微结构和元素特征，并确定这些晶体是否在这些环境中累积了碳酸盐沉积物。如果在这些环境中确实积累了这种材料，则代表了热带浅水碳酸盐沉积物的先前未识别的（潜在的体积重要）来源。

项目成果

Phase heterogeneity in carbonate production by marine fish influences their roles in sediment generation and the inorganic carbon cycle.

• DOI: 10.1038/s41598-017-00787-4
• 发表时间: 2017-04-10
• 期刊: Scientific reports
• 影响因子: 4.6
• 作者: Salter MA;Harborne AR;Perry CT;Wilson RW
• 通讯作者: Wilson RW

Size fraction analysis of fish-derived carbonates in shallow sub-tropical marine environments and a potentially unrecognised origin for peloidal carbonates

浅亚热带海洋环境中鱼类来源的碳酸盐的尺寸分数分析以及可能未被识别的球状碳酸盐的来源

• DOI: 10.1016/j.sedgeo.2014.10.005
• 发表时间: 2014
• 期刊: Sedimentary Geology
• 影响因子: 2.8
• 作者: Salter M

Production of mud-grade carbonates by marine fish: Crystalline products and their sedimentary significance

海鱼生产泥级碳酸盐：结晶产物及其沉积意义

• DOI: 10.1111/j.1365-3091.2012.01339.x
• 发表时间: 2012
• 期刊: Sedimentology
• 影响因子: 3.5
• 作者: SALTER M