Accretion patterns of Belize barrier and atoll reefs: an archive of environmental change during the Holocene

由于气候变暖、海洋酸化、污染和疾病，热带珊瑚礁的状况一直在下降（Pandolfi et al. 2003, 2011; Hughes et al. 2017; Eyre et al. 2018）。这在加勒比海地区的珊瑚礁中也很明显，活珊瑚覆盖面积减少（Gardner等人，2003年），许多珊瑚礁不再由珊瑚主导，而是由肉质藻类主导（Hughes 1994年），造礁的acroporid珊瑚和大型faviid珊瑚数量减少，取而代之的是杂草丛生的一般分类群（Perry等人，2015年；Kuffner和Toth 2016年），珊瑚礁增加潜力下降（Perry等人，2018年）。由于数以百万计的人生活在热带海岸和珊瑚礁岛屿上，并且由于这些人在社会经济上依赖珊瑚礁，因此这个问题并非纯粹的科学问题。对从现代珊瑚礁中提取的钻芯材料的研究，可以根据沉积学、古生态学和地质年代学分析，详细重建全新世的环境条件。基于这些数据，可以重建以前的生态和环境变化，从而可以决定当前的下降是否前所未有，并作为未来预测的基础。建议重新审视伯利兹屏障和环礁（大西洋最大的珊瑚礁系统）现有的核心材料，并进行额外的年龄测定，以限制珊瑚礁增生模式，确定动物变化的日期，并确定可能的珊瑚礁间隙。这将通过定量分析珊瑚礁组成和从22个岩心（全新世总长度213.4米）的珊瑚中获得约50个新的U/ th日期来实现，并将这些日期添加到58个现有的年龄日期中。作为一个有价值的副作用，伯利兹的区域全新世海平面曲线可以根据新时代数据进行精化。

The status of tropical coral reefs has been declining due to warming, ocean acidification, pollution, and disease (Pandolfi et al. 2003, 2011; Hughes et al. 2017; Eyre et al. 2018). This is also visible in reefs of the Caribbean realm in that live coral cover has diminished (Gardner et al. 2003), many reefs are no longer dominated by corals but fleshy algae (Hughes 1994), reef-building acroporid and massive faviid corals are reduced in abundance and replaced by weedy, generalistic taxa (Perry et al. 2015; Kuffner and Toth 2016), and reef accretion potential has decreased (Perry et al. 2018). As millions of people are living along tropical coasts and on reef islands and because these people are dependent on coral reefs socio-economically, this issue is not purely scientific. The study of drill core material extracted from modern coral reefs allows detailed reconstructions of environmental conditions during the Holocene based on sedimentological, paleoecological, and geochronological analyses. Based on these data, previous ecological and environmental changes can be reconstructed that may allow to decide whether or not current declines are unprecedented and serve also as basis for future predictions. It is proposed to revisit existing core material from Belize barrier and atoll reefs, the largest reef system in the Atantic, and to perform additional age dating to constrain patterns of reef accretion, date faunal changes, and identify possible reef gaps. This will be achieved by quantitatively analyzing reef composition and by obtaining some 50 new U/Th-dates from corals in 22 drill cores (total Holocene length 213.4 m) and to add these to 58 existing age dates. As a valuable side-effect, the regional Holocene sea-level curve of Belize can be refined based on the new age data.