Changes in the terrestrial environment and their effect on marine carbonates

与沿海开发相关的陆地径流增加导致悬浮在浅海水域的细颗粒，堵塞珊瑚骨架中的毛孔，减少到达珊瑚礁的阳光。与径流相关的过量营养物质也对珊瑚礁有害，因为它们对珊瑚宿主和它们的光合作用共生体之间的关系产生了负面影响。泥沙淤积和营养物质增加对珊瑚礁的直接影响是相当清楚的；然而，很少有研究考察加强风化的长期影响，或者非生物礁环境中产生碳酸盐的生物群如何受到这些压力因素的影响。这项研究计划的总体目标是评估陆地径流和相关营养物质在不同海洋环境中的影响，并通过一系列时间尺度进行评估。这项研究计划集中于两个主要目标：1)地球上最早的森林和土壤对泥盆纪(弗拉斯尼亚-380 Ma)生物礁的影响；2)现代非生物礁环境中径流的影响。弗拉斯尼亚时期森林的扩张和根系网络的发展，被称为斑点事件(Pe)，导致了世界上第一批土壤的形成。据推测，由于现代珊瑚礁的土壤径流增加，这一事件对世界海洋中产生碳酸盐的生物群产生了影响；然而，这一事件对弗拉斯尼亚珊瑚礁的影响尚未得到探索。这项拟议的研究考察了PE对加拿大西部沉积盆地保存完好的古代珊瑚礁的影响。这项研究还将涉及海洋页岩中生物来源的二氧化硅的相关性，这可能代表了与PE同时代的古代浮游植物水华，并对目前在世界范围内观察到的底层水缺氧加剧负有责任。这项研究建议的第二个方面调查了陆地径流、相关营养物质和重金属对两个现代环境中产生碳酸盐的生物群的影响：大开曼的一个泻湖和阿布扎比的一个内碳酸盐坡道。最近的沉积记录(&lt；1000年)将被询问有孔虫和沉积物的地球化学。有孔虫对营养水平的变化很敏感，与珊瑚相比，更大的共生有孔虫被多面手的分类群所取代。这些多面性分类群也与沉积物中的金属呈正相关。这项研究的最终目标是确定沿发达海岸线增加的径流如何影响非礁石环境中产生碳酸盐的海洋生物群，并制定标准，帮助我们认识古代环境中营养作用的影响。

Increased terrestrial runoff associated with coastal development results in fine particles suspended in shallow marine waters, which clogs pores in coral skeletons and reduces the amount of sunlight reaching the reefs. Excess nutrients associated with runoff are also harmful to reefs because they have negative impacts on the relationship between coral hosts and their photosynthetic symbionts. The immediate impacts of siltation and enhanced nutrients on reefs are fairly well understood; however, there are few studies examining the long-term effects of enhanced weathering or how carbonate producing biota in non-reef environments may be affected by these stressors. The overall objective of this research program is to evaluate the effects of terrestrial runoff and associated nutrients in various marine environments and through a range of timescales. This research proposal focuses on two main objectives that examine: 1) the effect the Earth's first forests and soils had on Devonian (Frasnian - 380 Ma) reefs; and 2) the effects of runoff in modern non-reef environments. The Frasnian expansion of forests and development of root networks, known as the punctata Event (pE), resulted in the world's first soils. It is assumed that this event had an effect on carbonate producing biota in the world's oceans since modern reefs suffer from increased soil runoff; however, the effects of this event on Frasnian reefs has not been explored. The proposed research examines the impact of the pE on ancient reefs that are well-preserved in the Western Canadian Sedimentary Basin. The research will also entail correlation of biogenically-sourced silicas in marine shales, which may represent ancient phytoplankton blooms, coeval with the pE, and responsible for enhanced bottom water anoxia observed worldwide at this time. The second aspect of this research proposal investigates the impact of terrestrial runoff, associated nutrients, and heavy metals on carbonate-producing biota in two modern settings: a lagoon in Grand Cayman and across an inner carbonate ramp in Abu Dhabi. The recent sedimentary record (<1000 years) will be interrogated for foraminifera and sediment geochemistry. Foraminifera are sensitive to changes in nutrient levels where, comparable to corals, larger symbiont-bearing foraminifera are replaced by generalist taxa. These generalist taxa also positively correlate with metals in sediments. The ultimate goal of this research is to determine how increased runoff along developed coastlines has impacted carbonate-producing marine biota in non-reef environments and develop criteria that may help us to recognize the effects of nutrification in ancient environments.