Browne Nicola, Braoun Christina, McIlwain Jennifer, Nagarajan Ramasamy, Zinke Jens
Molecular and Life Sciences, Curtin University, Perth, WA, Australia.
Curtin Malaysia Research Institute, Curtin University, Miri, Sarawak, Malaysia.
PeerJ. 2019 Aug 14;7:e7382. doi: 10.7717/peerj.7382. eCollection 2019.
For reefs in South East Asia the synergistic effects of rapid land development, insufficient environmental policies and a lack of enforcement has led to poor water quality and compromised coral health from increased sediment and pollution. Those inshore turbid coral reefs, subject to significant sediment inputs, may also inherit some resilience to the effects of thermal stress and coral bleaching. We studied the inshore turbid reefs near Miri, in northwest Borneo through a comprehensive assessment of coral cover and health in addition to quantifying sediment-related parameters. Although Miri's Reefs had comparatively low coral species diversity, dominated by massive and encrusting forms of , , , , and , they were characterized by a healthy cover ranging from 22 to 39%. We found a strong inshore to offshore gradient in hard coral cover, diversity and community composition as a direct result of spatial differences in sediment at distances <10 km. As well as distance to shore, we included other environmental variables like reef depth and sediment trap accumulation and particle size that explained 62.5% of variation in benthic composition among sites. Miri's reefs showed little evidence of coral disease and relatively low prevalence of compromised health signs including bleaching (6.7%), bioerosion (6.6%), pigmentation response (2.2%), scars (1.1%) and excessive mucus production (0.5%). Tagged colonies of and suffering partial bleaching in 2016 had fully (90-100%) recovered the following year. There were, however, seasonal differences in bioerosion rates, which increased five-fold after the 2017 wet season. Differences in measures of coral physiology, like that of symbiont density and chlorophyll for , and , were not detected among sites. We conclude that Miri's reefs may be in a temporally stable state given minimal recently dead coral and a limited decline in coral cover over the last two decades. This study provides further evidence that turbid coral reefs exposed to seasonally elevated sediment loads can exhibit relatively high coral cover and be resilient to disease and elevated sea surface temperatures.
在东南亚，快速的土地开发、环境政策不足以及执法不力的协同效应导致水质恶化，沉积物和污染增加，珊瑚健康受到损害。那些受到大量沉积物输入影响的近岸浑浊珊瑚礁，可能也继承了一些对热应激和珊瑚白化影响的恢复力。我们通过全面评估珊瑚覆盖率和健康状况，以及量化与沉积物相关的参数，对婆罗洲西北部美里附近的近岸浑浊珊瑚礁进行了研究。尽管美里的珊瑚礁珊瑚物种多样性相对较低，主要由块状和覆盖状的 、 、 、 、 和 组成，但它们的健康覆盖率在22%至39%之间。我们发现，由于距离<10公里处沉积物的空间差异，硬珊瑚覆盖率、多样性和群落组成存在明显的近岸到近海梯度。除了离岸距离外，我们还纳入了其他环境变量，如礁体深度、沉积物捕集器积累量和颗粒大小，这些变量解释了各站点底栖生物组成变化的62.5%。美里的珊瑚礁几乎没有珊瑚疾病的迹象，健康受损迹象的发生率相对较低，包括白化（6.7%）、生物侵蚀（6.6%）、色素沉着反应（2.2%）、伤疤（1.1%）和过多黏液分泌（0.5%）。2016年部分白化的标记 和 群体在次年完全（90 - 100%）恢复。然而，生物侵蚀率存在季节性差异，在2017年雨季过后增加了五倍。在各站点之间未检测到珊瑚生理学指标的差异，如 、 和 的共生体密度和叶绿素 。我们得出结论，鉴于最近死亡珊瑚极少，且在过去二十年中珊瑚覆盖率下降有限，美里的珊瑚礁可能处于暂时稳定状态。这项研究进一步证明，暴露于季节性沉积物负荷升高的浑浊珊瑚礁可以表现出相对较高的珊瑚覆盖率，并且对疾病和海面温度升高具有恢复力。
