The influence of turbidity on ancient and modern coral reefs

通过两个新生代过热事件(全球变暖的时间间隔)，研究了浑浊水在珊瑚和珊瑚礁生存中所起的作用。长期以来，不同的珊瑚礁系统被认为是仅限于清水环境的现象。碎屑沉积物输入高的地区被认为对珊瑚有害，因为水透明度降低(珊瑚共生体减少光合作用)，细粒沉积物堵塞固着底栖动物的取食/呼吸装置，以及水柱中营养物质和颗粒有机物增加(这导致大规模藻类定居和珊瑚分类群窒息)。不幸的是，清澈的水环境并不能缓解水温升高和气候变暖导致的长期无云的强烈太阳辐射，因此，近年来广泛的漂白导致热带珊瑚和珊瑚礁的广泛死亡。最近的研究表明，适度的浑浊(云量)可能会通过保护珊瑚类群免受高太阳辐射的影响而降低珊瑚礁压力，而不是让珊瑚礁窒息。最近的几项研究发现，浑浊系统(浑浊水域)的珊瑚礁是珊瑚礁的避难所，在那里，珊瑚礁生物群可能会撤退并在环境危机中生存下来。尽管浑水珊瑚礁很重要，但相对于清水珊瑚礁，人们对它们的了解很少。这项研究计划的目标是调查浑浊水域珊瑚礁在高温事件期间在维持区域珊瑚礁健康和珊瑚礁动物多样性方面所发挥的作用。研究了两个超热区间。年代较早的是古新世-始新世最热(PETM)-早始新世气候最佳(EECO)时间段(约5600万至4900万年前)，其中包括直到今天地球上最热的时间段。新特提斯地区(现代南欧)最新的古新世至早始新世的生物礁是我研究的重点，因为这一地区是古近纪生物礁多样性的中心，通过纯碳酸盐和混合硅屑-碳酸盐序列可以获得厚厚的垂直连续的、有生物礁倾向的露头。考虑的较年轻的时间段是中更新世至现代。在这里，我的焦点是印度尼西亚Sumba的东北海岸。Sumba位于珊瑚三角，这是地球上最多样化的海洋生态系统，拥有世界76%的珊瑚物种和37%的珊瑚鱼类物种。大量的漂白导致了这些热带珊瑚和珊瑚礁的广泛灭绝。之所以选择松巴岛，是因为它包括一百万年来珊瑚礁隆起的记录，包括古代和现代的浊水和清水珊瑚礁，靠近沃拉西亚海峡的一个岛屿上(这是一个岛屿丰富的地区，位于萨胡尔和舜达陆架之间，在更新世期间被地下暴露)。

The role that turbid water has played in coral and coral reef survival through two Cenozoic hyperthermal events (temporal intervals of global warming) is investigated. Diverse coral reef systems were long considered to be phenomena limited to clear water settings. Areas of high clastic sediment input were considered to be harmful to corals due to reduced water transparency (reducing photosynthesis by coral symbionts), fine-grained sediment clogging the feeding / respiration apparatus of sessile benthic faunas and increased nutrients and particulate organics in the water column (which causes extensive algal colonization and smothering of coral taxa). Unfortunately, clear water settings provide no respite from increased water temperatures and prolonged, cloudless exposure to intense solar radiation that result from a warming climate and thus, in recent years extensive bleachings have resulted in the widespread demise of tropical corals and coral reefs. Recent studies have suggested that, rather than smothering reefs, moderate levels of turbidity (cloudiness) may lower reef stress by shielding coral taxa from high solar radiation. Several recent studies have identified turbid-system (murky water) coral reefs as refugia wherein reef biota may retreat and survive environmental crises. Despite the importance of turbid water coral reefs, they are poorly understood relative to their clear-water equivalents. The goal of this research program is to investigate the role that turbid water coral reefs play and have played in maintaining regional coral reef health and reef fauna diversity during hyperthermal events. Two hyperthermal intervals are investigated. The older interval is the Paleocene-Eocene Thermal Maximum (PETM) - Early Eocene Climate Optimum (EECO) interval (~56 to 49 million years ago), which includes the warmest interval on the earth up until the present day. Latest Paleocene to early Eocene reefs in the neoTethys region (modern southern Europe) are my focus for this research program as this area was the centre of reef diversity during the Paleogene and thick vertically continuous, reef-prone outcrop is available through both pure carbonate and mixed siliciclastic-carbonate successions. The younger interval considered is the Middle Pleistocene to Modern. Here my focus is on the northeastern coast of Sumba, Indonesia. Sumba occurs in the Coral Triangle, the most diverse marine ecosystem on the planet, hosting 76% of the world's coral species and 37% of coral fish species. extensive bleaching has resulted in the widespread demise of these tropical corals and coral reefs. The island of Sumba was chosen as it includes an one-million year record of uplifted coral reefs, includes ancient and modern turbid-water and clear-water coral reefs in close proximity and occurs on an island in the Wallacea straits (an island-rich region that occurs between the Sahul and Sunda shelves, which were subaerially exposed during the Pleistocene).