Evidence of very rapid reef accretion and reef growth under high turbidity and terrigenous sedimentation
Evidence of very rapid reef accretion and reef growth under high turbidity and terrigenous sedimentation
复制标题
高浊度和陆源沉积条件下珊瑚礁快速增生和生长的证据
作者：
C. Perry;S. Smithers;P. Gulliver;N. Browne
全球范围内珊瑚礁健康状况的恶化预计将导致造礁潜力逐步下降，最终导致珊瑚礁净侵蚀状态。这些转变可能是由各种人类干扰和气候变化驱动的；然而，人们普遍认为，人类改造的沿海集水区增加的陆地沉积物和养分产量是一个主要威胁。随着水质恶化，珊瑚覆盖率和物种多样性通常被推断为减少，珊瑚礁增加率降低和珊瑚礁发育受损是假定的后果。在这里，我们展示了详细的年代地层生长历史，受40个加速器质谱仪放射性碳测年的限制，中礁是澳大利亚大堡礁上的近岸浑浊带珊瑚礁，这挑战了高陆地沉积物输入内在地限制了珊瑚礁增长速度和抑制珊瑚礁发育的假设。我们发现，中礁在过去700多年里以8.3myr⁻？的平均速度在垂直方向上快速增长。珊瑚礁的沉积速率在不同的时期有所不同，但值得注意的是，最快速的沉积时期(平均13.0mm yr⁻？)与以细粒陆屑沉积沉积为主的生物礁发育阶段相吻合。我们认为，这在很大程度上是陆源沉积物快速堆积的作用，有助于珊瑚骨骼材料的死后保存。在过去9000年里，该区域大多数清水礁、中陆架和外陆架珊瑚礁的最大增长率和站点平均增长率都达到或超过了记录的增长率，而同期印度洋和太平洋上许多珊瑚礁的增长率也达到或超过了记录的增长率。虽然近岸珊瑚礁在短期内因过度陆地沉积而退化的例子显然存在，但其他珊瑚礁显然可以容忍高度的沉积和浑浊，我们的数据证实，在这些环境中，珊瑚礁的持续和长期快速生长是可能的。
Global-scale deteriorations in coral reef health are projected to lead to a progressive decline in reef-building potential and ultimately to states of net reef erosion. These transitions may be driven by various human disturbances and by climate change; however, increased terrestrial sediment and nutrient yields from anthropogenically modified coastal catchments are widely recognized as a major threat. As water quality deteriorates, reduced coral cover and species diversity are commonly inferred, and lower reef accretion rates and impaired reef development are assumed consequences. Here we present a detailed chronostratigraphic growth history, constrained by 40 accelerator mass spectrometry radiocarbon dates for Middle Reef, an inshore turbid-zone reef on Australia's Great Barrier Reef, that challenges the assumption that high terrestrial sediment inputs inherently restrict reef accretion rates and inhibit reef development. We establish that Middle Reef has vertically accreted very rapidly for more than 700 yr, at an average rate of 8.3 mm yr⁻¹. Accretion rates varied across the reef at different times, but it is significant that the periods of most rapid accretion (averaging 13.0 mm yr⁻¹) coincide with phases of reef development dominated by fine-grained terrigenoclastic sediment accumulation. We suggest that this is in large part a function of a high rate of terrigenous sediment accumulation aiding the postmortem preservation of coral skeletal material. Both maximum and site-averaged accretion rates match or exceed those documented for most clear-water, mid- and outer-shelf reefs in the region over the past 9000 yr, and those determined for many reefs throughout the Indian and Pacific Oceans over the same period. While examples of inshore coral reefs that have been degraded in the short term by excessive terrestrial sedimentation clearly exist, others clearly tolerate high sedimentation and turbidity, and our data confirm that sustained and long-term rapid reef growth is possible in these environments.
全新世晚期海平面高位期间浑浊带珊瑚礁间歇性“开启”和“关闭”的证据
影响因子：
5.8
作者：
Perry C
通讯作者：
Perry C