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热带海洋学报

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西沙珊瑚礁浅层与中光层有孔虫碳、氧同位素特征及其连通性指示意义

陈天然1, 周雯1, 林先智1, 李淑2, 吴静淇3, 王子洋4, 刘胜1

  

  1. 1. 中国科学院南海海洋研究所, 热带海洋环境与岛礁生态全国重点实验室, 广东 广州 510301;

    2. 中国科学院南海海洋研究所, 边缘海与大洋地质实验室, 广东 广州 510301;

    3. 广州市第三中学, 广东 广州 510120;

    4. 北京师范大学广州实验学校, 广东 广州 510700


  • 收稿日期:2026-08-28 修回日期:2026-09-07 接受日期:2026-10-15
  • 通讯作者: 刘胜
  • 基金资助:

    科技基础资源调查专项(2022FY100600); 热带海洋环境与岛礁生态全国重点实验室自主项目(E6YQ2A0203)

Carbon‑Oxygen Isotope Signatures of Benthic Foraminifera and Their Implications for Vertical Connectivity Between Shallow‑Water and Upper‑Mesophotic Zones of Xisha Coral Reefs

CHEN Tianran1, ZHOU Wen1, LIN Xianzhi1, LI Shu2, WU Jingqi3, WANG Ziyang4, LIU Sheng1    

  1. 1.  State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;

    2.  Laboratory of Marginal Sea and Ocean Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;

    3.  Guangzhou No. 3 Middle School, Guangzhou 510120, China;

    4.  Guangzhou Experimental School Affiliated to Beijing Normal University, Guangzhou 510700, China



  • Received:2026-08-28 Revised:2026-09-07 Accepted:2026-10-15
  • Supported by:

    : Science & Technology Fundamental Resources Investigation Program (2022FY100600); Project of State Key Laboratory of Tropical Oceanography (E6YQ2A0203)

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摘要： 中光层珊瑚生态系统（mesophotic coral ecosystems，MCEs）被视为浅水珊瑚面对气候变暖的潜在 “深礁避难所”，但其功能实现高度依赖浅水区与上部中光层之间的水体交换与垂直物质连通。目前垂直连通性研究多聚焦种群遗传学，而礁坡物质连通的直接地球化学证据仍然不足。本文以西沙群岛羚羊礁和赵述岛向海礁坡表层沉积物中的单种底栖有孔虫（Amphisorus sp.）为记录载体，获取浅水（3 20 m）与上部中光层（35 48 m）共48 组壳体δ¹³C和δ¹⁸O同位素数据。结果表明：浅水与上部中光层δ¹³C 没有显著统计学差异，两组数据高度重叠，未检测到显著DIC碳库的空间分异；δ¹⁸O 随水深增加显著偏正，经协方差分析（ANCOVA）控制水深效应后，δ¹⁸O 组间效应接近但未达到预设α=0.05 的统计显著水平，说明氧同位素差异主要来源于连续水深-温度梯度。同位素证据表明，西沙礁坡浅水 上部中光层可能存在较强的跨水深水体与物质交换。本研究利用底栖有孔虫碳、氧同位素，提供礁坡碳库连通的原位地球化学证据，补充了传统遗传连通研究之外的物质连通视角。同时，本文为西沙有孔虫古环境代用指标重建提供现代过程校正参考，也为西沙中光层珊瑚生态系统的保护与管理提供科学依据。

关键词: 西沙群岛, 中光层珊瑚礁, 底栖有孔虫, 碳、氧稳定同位素, 垂直连通性

Abstract: Mesophotic coral ecosystems (MCEs) are regarded as potential “deep‑reef refugia” for shallow‑water corals under climate warming. However, their functional integrity largely relies on water‑mass exchange and vertical material connectivity between shallow‑water and upper‑mesophotic zones. Previous studies on vertical connectivity have primarily focused on population genetics, whereas direct geochemical evidence for material connectivity across reef slopes remains limited. In this study, we employed monospecific benthic foraminifera (Amphisorus sp.) extracted from surface sediments on the fore‑reef slopes of Lingyang Reef and Zhaoshu Island, Xisha Archipelago, as geochemical archives. A total of 48 paired δ¹³C and δ¹⁸O isotopic datasets were obtained, comprising 24 samples from the shallow‑water zone (3‑20 m) and 24 from the upper‑mesophotic zone (35‑48 m). The results show that δ¹³C exhibits no statistically significant difference between the shallow‑water and upper‑mesophotic groups, with substantial overlap of datasets, indicating no significant spatial differentiation of DIC isotopic signals. In contrast, δ¹⁸O increases significantly with water depth. After controlling for depth effects via analysis of covariance (ANCOVA), the between‑group effect on δ¹⁸O approaches but does not reach the pre‑set significance level of α = 0.05, suggesting that the δ¹⁸O discrepancy mainly arises from the continuous depth‑dependent temperature gradient. Isotopic evidence supports the hypothesis of vertical material connectivity and implies likely intense cross‑depth water‑mass exchange on Xisha reef slopes. This study provides in‑situ geochemical evidence for carbon‑pool connectivity based on benthic foraminiferal isotopes, offering a material‑based perspective complementary to conventional genetic‑connectivity research. Furthermore, it supplies modern‑process calibration references for paleoenvironmental reconstruction using fossil foraminifera from Xisha coral reefs, and provides scientific support for the conservation and management of mesophotic coral ecosystems in the Xisha Archipelago. Key words: Xisha Islands; mesophotic coral reefs; benthic foraminifera; carbon and oxygen stable isotopes; vertical connectivity

Key words: Xisha Islands, mesophotic coral reefs, benthic foraminifera, carbon and oxygen stable isotopes, vertical connectivity