有孔虫指数(Foram Index,FI)是利用珊瑚礁区沉积物中底栖有孔虫功能组(藻类共生种、机会种、非自养种)的含量评估珊瑚礁区生态环境健康状况的指标,迄今中国对该指标的应用还较少。文章以西沙群岛羚羊礁的潟湖中钻取的LYJ2岩芯为材料(全...有孔虫指数(Foram Index,FI)是利用珊瑚礁区沉积物中底栖有孔虫功能组(藻类共生种、机会种、非自养种)的含量评估珊瑚礁区生态环境健康状况的指标,迄今中国对该指标的应用还较少。文章以西沙群岛羚羊礁的潟湖中钻取的LYJ2岩芯为材料(全长287 cm,底部对应的年代为2665 a BP),以0.5 cm的间隔取样,在显微镜下鉴定有孔虫功能组,计算FI值。结果显示:1)近2600年的FI变化范围为4.1~7.9,均值为5.9。2)FI成波动变化的模式,具体可分为3个上升期:2380―1628,1212―572和252―92 a BP;3个快速下降期:1628―1212,572―252和92 a BP至今及1个小幅下降期:2665―2380 a BP;3)FI在长期变化趋势上叠加不同尺度的年代际波动,具有66.7、54.4 a等周期。基于FI值对珊瑚礁健康状况的评估标准,推测近2600年来西沙羚羊礁的生态环境总体是健康的;基于FI值与海表温度对比分析,推测羚羊礁FI值主要受海表温度影响,与气候变化具有一致性,FI高值与中世纪暖期、罗马暖期大致对应,而低值与小冰期、黑暗时代冷期大致对应;FI值具有3次快速下降阶段,前两者(1628―1404,572―252 a BP)与黑暗时代冷期、小冰期相对应,可能是由于冷期冬季风增强导致大气粉尘物质增多、降雨增加、羚羊礁海域营养物质增加所致;后者(92 a BP至今)与近40年来西沙群岛珊瑚礁生态系统的快速退化相对应,可能是由人类活动加剧、大气氮沉降通量增加等导致的羚羊礁海域营养浓度升高所致。文章揭示了有孔虫指数可大体记录南海珊瑚礁的健康状况,可用于对地质历史时期珊瑚礁健康状况的评估。展开更多
Coral reefs are in terminal decline.For conservation to be effective,naturally depauperate reefs must be distinguished from those recently degraded by humans.Traditional reef monitoring is time consuming and lacks the...Coral reefs are in terminal decline.For conservation to be effective,naturally depauperate reefs must be distinguished from those recently degraded by humans.Traditional reef monitoring is time consuming and lacks the longevity to make this distinction.Success in using foraminifera as bioindicators for reef health has hitherto levered their response to nutrients.Because ocean heat waves are the dominant driver of coral bleaching and death,there is compelling motivation to develop new foraminiferal bioindicators that inform on temperature stress over meaningful timescales.This study focuses on identifying which foraminifera respond systematically to the temperature stress that kills corals.Statistical models were used to compare endosymbiont-bearing foraminiferal families,collected along a heat-stress gradient spanning the Solomon Islands and New Caledonia,to live coral cover at the same sites.Results indicate that Amphisteginidae foraminifera and coral cover show a significant decline in abundance as heat stress increases along the transect sites.Furthermore,ocean productivity and salinity,both recognized environmental influences on foraminifera,are shown to be subordinate to temperature in their sway of this ecological patterning.These findings indicate the potential for using foraminifera to develop new indices capable of quantifying long-term thermal impacts on reefs.展开更多
文摘有孔虫指数(Foram Index,FI)是利用珊瑚礁区沉积物中底栖有孔虫功能组(藻类共生种、机会种、非自养种)的含量评估珊瑚礁区生态环境健康状况的指标,迄今中国对该指标的应用还较少。文章以西沙群岛羚羊礁的潟湖中钻取的LYJ2岩芯为材料(全长287 cm,底部对应的年代为2665 a BP),以0.5 cm的间隔取样,在显微镜下鉴定有孔虫功能组,计算FI值。结果显示:1)近2600年的FI变化范围为4.1~7.9,均值为5.9。2)FI成波动变化的模式,具体可分为3个上升期:2380―1628,1212―572和252―92 a BP;3个快速下降期:1628―1212,572―252和92 a BP至今及1个小幅下降期:2665―2380 a BP;3)FI在长期变化趋势上叠加不同尺度的年代际波动,具有66.7、54.4 a等周期。基于FI值对珊瑚礁健康状况的评估标准,推测近2600年来西沙羚羊礁的生态环境总体是健康的;基于FI值与海表温度对比分析,推测羚羊礁FI值主要受海表温度影响,与气候变化具有一致性,FI高值与中世纪暖期、罗马暖期大致对应,而低值与小冰期、黑暗时代冷期大致对应;FI值具有3次快速下降阶段,前两者(1628―1404,572―252 a BP)与黑暗时代冷期、小冰期相对应,可能是由于冷期冬季风增强导致大气粉尘物质增多、降雨增加、羚羊礁海域营养物质增加所致;后者(92 a BP至今)与近40年来西沙群岛珊瑚礁生态系统的快速退化相对应,可能是由人类活动加剧、大气氮沉降通量增加等导致的羚羊礁海域营养浓度升高所致。文章揭示了有孔虫指数可大体记录南海珊瑚礁的健康状况,可用于对地质历史时期珊瑚礁健康状况的评估。
基金supported by the National Science Foundation(NSF)(No.EAR-2035135)。
文摘Coral reefs are in terminal decline.For conservation to be effective,naturally depauperate reefs must be distinguished from those recently degraded by humans.Traditional reef monitoring is time consuming and lacks the longevity to make this distinction.Success in using foraminifera as bioindicators for reef health has hitherto levered their response to nutrients.Because ocean heat waves are the dominant driver of coral bleaching and death,there is compelling motivation to develop new foraminiferal bioindicators that inform on temperature stress over meaningful timescales.This study focuses on identifying which foraminifera respond systematically to the temperature stress that kills corals.Statistical models were used to compare endosymbiont-bearing foraminiferal families,collected along a heat-stress gradient spanning the Solomon Islands and New Caledonia,to live coral cover at the same sites.Results indicate that Amphisteginidae foraminifera and coral cover show a significant decline in abundance as heat stress increases along the transect sites.Furthermore,ocean productivity and salinity,both recognized environmental influences on foraminifera,are shown to be subordinate to temperature in their sway of this ecological patterning.These findings indicate the potential for using foraminifera to develop new indices capable of quantifying long-term thermal impacts on reefs.
