南沙群岛现代滨珊瑚骨骼Sr/Ca、δ^(18)O和δ^(13)C对极端高温事件响应  

The Responses of Sr/Ca, δ^(18)O, and δ^(13)C in the Porites Coral Skeleton to Extreme Thermal Events in the Nansha Islands

作　　者：徐潇峰 余克服 陈天然 陶士臣[1] 严宏强[1] 陈特固 Xu Xiaofeng;Yu Kefu;Chen Tianran;Tao Shichen;Yan Hongqiang;Chen Tegu(Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,China;University of Chinese Academy of Sciences,Beijing 100049,China;Guangxi Laboratory on the Study of Coral Reefs in the South China Sea,Coral Reef Research Center of China,School of Marine Sciences,Guangxi University,Nanning 530004,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519080,China)

机构地区：[1]中国科学院边缘海与大洋地质重点实验室,南海海洋研究所,广州510301 [2]中国科学院大学,北京100049 [3]广西大学珊瑚礁研究中心,广西南海珊瑚礁研究重点实验室,广西大学海洋学院,南宁530004 [4]南方海洋科学与工程实验室,广东珠海519080

出　　处：《热带地理》2022年第11期1771-1782,共12页Tropical Geography

基　　金：国家自然科学基金(42030502、42090041)。

摘　　要：以南沙群岛永暑礁的现代滨珊瑚YSL24(生长时间为1985-1999年)与YSL2A(生长时间为1971-1999年)为材料,通过对其骨骼开展高分辨率的Sr/Ca、^(18)δO和^(13)δC分析,探讨其对极端高温事件的响应特征。有记录表明,1971-1999年,南海南部在1973、1983和1998年发生了极端高温事件,滨珊瑚骨骼Sr/Ca序列清楚地记录了这3次高温事件,其相应条带Sr/Ca周期数值显著低于序列其他年份。而^(18)δO对高温事件的响应不太明显,其原因可能与^(18)δO序列同时受温度和盐度变化的影响有关。^(13)δC在这3个高温年份均在夏季发生了异常负偏,应该是由高温胁迫下共生藻光合作用强度下降所致。因此,珊瑚骨骼的Sr/Ca和^(13)δC对南沙群岛高温胁迫具有明显的响应,可作为记录过去白化事件的可靠指标。In recent years, extreme thermal events have become one of the main reasons for coral reef degradation. Determining the variation of coral skeletal geochemical proxies in response to extreme thermal events would be vital evidence for reconstructing historical extreme thermal events using corals. In this study,cores from modern Porites corals YSL24 that lived in 1987-1999 and YSL2A that lived in 1971-1999 were collected from the Yongshu Reef, Nansha Islands, southern South China Sea(SCS) for high-resolution analysis of skeletal Sr/Ca, ^(18)δO, and ^(13)δC to determine the responses of these geochemical proxies to past extreme warming events. There is evidence that extreme warming events occurred in 1973, 1983 and 1998 in the southern SCS during the period 1971-1999. The Sr/Ca ratios in the Porites corals showed a significant negative correlation with the variation in local sea surface temperature(SST), and the values in the bands of these three years were much lower. This suggested a clear record of higher temperatures than other years in response to the warming events in these episodes. Compared with the Sr/Ca ratios, skeletal ^(18)δO proxies in the two Porites corals also revealed a negative correlation with SST, but the ^(18)δO values in these three bands were likely to be less sensitive to the thermal events. This is mainly because the variation in this proxy was controlled by both local SST and sea surface salinity, while the two factors had opposite effects on the seasonal variation of coral ^(18)δO in the SCS. After the removal of the SST contributions, the ^(18)δO series of the Porites corals showed clear annual cycles and a negative correlation with seasonal precipitation, but the records in the bands of those warming years did not reveal clear anomalous shifts due to thermal stress, which might be an inappropriate proxy for identifying extreme warming episodes. In the skeletal ^(13)δC series of Porites corals, an abnormal negative shift was detected during the summers of 1973, 1983, and 1998. This

关 键 词：滨珊瑚骨骼 地化指标 珊瑚白化 高温事件 δ^(13)C负偏 南沙群岛 

分 类 号：P597[天文地球—地球化学]