Cycles of coral reef 'turn-on', rapid growth and 'turn-off' over the past 8500 years: a context for understanding modern ecological states and trajectories
Cycles of coral reef 'turn-on', rapid growth and 'turn-off' over the past 8500 years: a context for understanding modern ecological states and trajectories
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DOI：
10.1111/j.1365-2486.2010.02181.x
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发表时间：
2011-01-01
影响因子：
11.6
通讯作者：
Smithers, Scott G.
中科院分区：
文献类型：
--
作者：
Perry, Chris T.;Smithers, Scott G.
人类活动威胁着全球的珊瑚礁生态系统，迫使生态变化的速度和规模在全新世被认为是前所未有的。这些变化是如此深刻，以至于许多人认为，停止珊瑚礁增生（珊瑚礁“关闭”）和珊瑚礁结构的净侵蚀是最终和即将发生的轨迹。在这里，我们使用一个区域规模的珊瑚礁生长数据集，根据76个核心记录（211放射性日期的约束）从22个珊瑚礁沿着和整个大陆架的大堡礁，澳大利亚，检查时间的不同阶段的珊瑚礁启动（“打开”），增长和“关闭”在全新世。该数据集描绘了过去8500年来两个时间离散的造礁事件：第一个与全新世海侵早期高位期[类似于8.5-5.5 k校准年bp（cal ybp）];第二个与2.3 k cal ybp相似。在这两个时期，珊瑚礁迅速增生到海平面，然后进入晚期进化状态-状态自然的特点是减少珊瑚覆盖和低增生潜力-和一个明确的间隙发生在这些造礁事件之间，没有记录的珊瑚礁的启动存在。这些过渡模仿目前的环境扰动制度下的预测，但已完全由自然强迫因素驱动。我们的研究结果表明，即使在全新世晚期，珊瑚礁的健康和增长波动周期独立的人为强迫。因此，退化的珊瑚礁状态事实上不能被认为自动反映了人为压力的增加。事实上，在许多情况下，退化或非增生的珊瑚礁群落可能反映了过去的珊瑚礁生长历史（由珊瑚礁生长-海平面相互作用决定）以及当代环境变化。认识到珊瑚礁状况的变化何时反映了这些自然的“开启”-生长-“关闭”周期，以及它们如何与持续的人类干扰相互作用，对于有效的珊瑚礁管理和了解未来的珊瑚礁生态轨迹至关重要。
Human activities threaten reef ecosystems globally, forcing ecological change at rates and scales regarded as unprecedented in the Holocene. These changes are so profound that a cessation of reef accretion (reef 'turn-off') and net erosion of reef structures is argued by many as the ultimate and imminent trajectory. Here, we use a regional scale reef growth dataset, based on 76 core records (constrained by 211 radiometric dates) from 22 reefs along and across the inner-shelf of the Great Barrier Reef, Australia, to examine the timing of different phases of reef initiation ('turn-on'), growth and 'turn-off' during the Holocene. This dataset delineates two temporally discrete episodes of reef-building over the last 8500 years: the first associated with the Holocene transgression-early highstand period [similar to 8.5-5.5 k calibrated years bp (cal ybp)]; the second since similar to 2.3 k cal ybp. During both periods, reefs accreted rapidly to sea level before entering late evolutionary states - states naturally characterized by reduced coral cover and low accretion potential - and a clear hiatus occurs between these reef-building episodes for which no records of reef initiation exist. These transitions mimic those projected under current environmental disturbance regimes, but have been driven entirely by natural forcing factors. Our results demonstrate that, even through the late Holocene, reef health and growth has fluctuated through cycles independent of anthropogenic forcing. Consequently, degraded reef states cannot de facto be considered to automatically reflect increased anthropogenic stress. Indeed, in many cases degraded or nonaccreting reef communities may reflect past reef growth histories (as dictated by reef growth-sea level interactions) as much as contemporary environmental change. Recognizing when changes in reef condition reflect these natural 'turn-on' - growth - 'turn-off' cycles and how they interact with on-going human disturbance is critical for effective coral reef management and for understanding future reef ecological trajectories.