Nearshore Turbid-Zone Corals Exhibit High Bleaching Tolerance on the Great Barrier Reef Following the 2016 Ocean Warming Event
Nearshore Turbid-Zone Corals Exhibit High Bleaching Tolerance on the Great Barrier Reef Following the 2016 Ocean Warming Event
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DOI：
10.3389/fmars.2017.00224
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发表时间：
2017-07
影响因子：
3.7
通讯作者：
K. Morgan;C. Perry;J. Johnson;S. Smithers
中科院分区：
文献类型：
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作者：
K. Morgan;C. Perry;J. Johnson;S. Smithers
2015/2016年夏季，大堡礁（GBR）的高海面温度（SST）导致了大范围的珊瑚漂白，航空和水中调查证实了与漂白相关的高（但可变）珊瑚死亡率。相比之下，漂白对近岸浊流区珊瑚礁的影响，传统上被认为是更"边缘"的珊瑚栖息地，仍然很少有记录。这是因为在这些浑浊的水环境中进行快速的生态调查是困难的，并且用于量化干扰的基线珊瑚群落数据很少。然而，模型表明，近岸环境的极端环境条件（例如，海洋环境变化（包括浊度、光照和温度波动）可能使珊瑚适应与近海珊瑚礁漂白有关的热异常，尽管迄今为止实地证据的验证很少。在这里，我们提出了一个新的前（2013年6月/2014年）和变暖后（2016年8月）的浊流区珊瑚群落的评估，并检查珊瑚的反应，长期和急性热应力内的Paluma浅滩珊瑚礁复合体，位于中央GBR。我们分析了2，288个静态视频帧（约1，200平方米），其中包括11，374个珊瑚群落（24个珊瑚属），结果表明浊层珊瑚对漂白的耐受性很高，珊瑚覆盖率（前：48 ± 20%;后：55 ± 26%）或珊瑚群落结构（例如，Acropora，Montipora，Turbinaria，Porites）。事实上，只有一个珊瑚群落（Lobophyllia sp.）表现出完全的菌落漂白，只有1.5%的菌落表现出部分色素沉着损失（<20%的菌落表面）。特定类群对这一热应力事件的反应与清水评估形成对比，因为通常被报道为对清水珊瑚礁漂白非常敏感的鹿角珊瑚在Paluma Shoals受到的影响最小，这是在其他浑浊环境中观察到的现象。重要的是，实地调查证实，区域SST足够高，足以引起珊瑚漂白（即，近岸和近海地区的加热天数相当），但GBR中心近海站点的漂白严重程度要高得多。我们的研究结果可能暗示了一个比一般为GBR中部近岸珊瑚礁提供的更乐观的前景，这突出了这些有弹性但经常被忽视的珊瑚礁栖息地在气候相关干扰期间作为潜在避难所的重要性。
High sea surface temperatures (SSTs) on the Great Barrier Reef (GBR) during summer 2015/2016 caused extensive coral bleaching, with aerial and in-water surveys confirming high (but variable) bleaching-related coral mortality. In contrast, bleaching impacts on nearshore turbid-zone reefs, traditionally considered more “marginal” coral habitats, remain poorly documented. This is because rapid ecological surveys are difficult in these turbid water settings, and baseline coral community data from which to quantify disturbance are rare. However, models suggest that the extreme environmental conditions characteristic of nearshore settings (e.g., fluctuating turbidity, light and temperature) may acclimate corals to the thermal anomalies associated with bleaching on offshore reefs, although validation by field evidence has to-date been sparse. Here we present a novel pre- (June 2013/2014) and post-warming (August 2016) assessment of turbid-zone coral communities and examine the response of corals to prolonged and acute heat stress within the Paluma Shoals reef complex, located on the central GBR. Our analysis of 2,288 still video frames (~1,200 m2) which include 11,374 coral colonies (24 coral genera) suggest a high tolerance of turbid-zone corals to bleaching, with no significant changes in coral cover (pre: 48 ± 20%; post: 55 ± 26%) or coral community structure (e.g., Acropora, Montipora, Turbinaria, Porites) following the warming event. Indeed, only one coral colony (Lobophyllia sp.) exhibited full colony bleaching, and just 1.5% of colonies displayed partial pigmentation loss (<20% colony surface). Taxa-specific responses to this thermal stress event contrast with clear-water assessments, as Acropora corals which are normally reported as highly susceptible to bleaching on clear-water reefs were least impacted at Paluma Shoals, a phenomena that has been observed within other turbid settings. Importantly, field surveys confirm regional SSTs were sufficiently high to induce coral bleaching (i.e., comparable number of degree heating days in nearshore and offshore areas), but bleaching severity was much higher at central GBR offshore sites. A more optimistic outlook than is generally offered for nearshore reefs on the central GBR may be implied by our results, which highlights the importance of these resilient but often overlooked coral reef habitats as potential refugia during climate-related disturbances.