Century-scale records of coral growth rates indicate that local stressors reduce coral thermal tolerance threshold
Century-scale records of coral growth rates indicate that local stressors reduce coral thermal tolerance threshold
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DOI：
10.1111/j.1365-2486.2009.02043.x
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发表时间：
2010-04-01
影响因子：
11.6
通讯作者：
McField, Melanie
中科院分区：
文献类型：
--
作者：
Carilli, Jessica E.;Norris, Richard D.;McField, Melanie
珊瑚白化，即珊瑚失去共生的鞭毛藻，在频率和地理范围上似乎都在增加，并且通常与异常高的水温和太阳辐照度有关。珊瑚礁生态学中的一个关键问题是，局部压力是否降低了珊瑚的热耐受阈值，从而导致白化发生率增加。利用树木年轮技术，我们制作了主要的珊瑚礁建造者——巨大的蒙塔斯特拉珊瑚——在过去75-150年间的生长速度的主年表，这些珊瑚来自中美洲珊瑚礁。我们的记录表明，1998年的大规模白化事件在上个世纪是前所未有的，尽管有证据表明，该地区的水温和太阳辐照度与近几十年来一样高或更高。我们测试了人口和热应力的相互作用对珊瑚扩展率的影响，这里用温度加热月（DHM）计算。我们发现，当考虑到以人口为代表的慢性局部压力因素的影响时，近期扩展率的下降比使用DHM作为唯一预测因子更能解释。因此，1998年中美洲珊瑚礁大规模白化的发生似乎源于慢性局部应激源的协同影响导致的热耐受性降低。
Coral bleaching, during which corals lose their symbiotic dinoflagellates, appears to be increasing in frequency and geographic extent, and is typically associated with abnormally high water temperatures and solar irradiance. A key question in coral reef ecology is whether local stressors reduce the coral thermal tolerance threshold, leading to increased bleaching incidence. Using tree-ring techniques, we produced master chronologies of growth rates in the dominant reef builder, massive Montastraea faveolata corals, over the past 75-150 years from the Mesoamerican Reef. Our records indicate that the 1998 mass bleaching event was unprecedented in the past century, despite evidence that water temperatures and solar irradiance in the region were as high or higher mid-century than in more recent decades. We tested the influence on coral extension rate from the interactive effects of human populations and thermal stress, calculated here with degree-heating-months (DHM). We find that when the effects of chronic local stressors, represented by human population, are taken into account, recent reductions in extension rate are better explained than when DHM is used as the sole predictor. Therefore, the occurrence of mass bleaching on the Mesoamerican reef in 1998 appears to stem from reduced thermal tolerance due to the synergistic impacts of chronic local stressors.