National Coral Reef Monitoring Program: Erosion data from bioerosion monitoring units (BMUs) deployed at select coral reef sites in the Pacific Ocean

The erosion rates provided in this collection were gathered from bioerosion monitoring units (BMUs) retrieved at existing long-term monitoring sites at Wake Island and the Hawaiian and Mariana Archipelagos during NOAA Pacific Islands Fisheries Science Center (PIFSC), Coral Reef Ecosystem Program (CREP) led National Coral Reef Monitoring Program (NCRMP) missions. The samples were analyzed at NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML), as part of NOAA's ongoing NCRMP. BMUs are constructed from clean coral skeletons and left on the reef for a period of 3 years. This collection of data contains the first run of BMUs that has ever been produced, and as such, the protocol established at the time was shortly thereafter amended in order to give a more thorough picture of bioerosion rates. Early analysis procedures utilized a benchtop micro computed tomography scanner (microCT, Bruker) for initial scans (pre-deployment), while post collection analyses (including those in this collection) were analyzed by a larger Computed Tomography device (CT scanner, Siemens).

BMUs are CT scanned for changes in density, volume and mass in which rates of bioerosion can be assessed. Annual erosion and accretion rates can be determined from these data in terms of loss of reef structure volume as well as mass in grams of calcium carbonate. Accretion rates given in this collection are determined by finding the volume of non-original carbonate material found on the external surface of the BMUs divided by the number of years the BMU was deployed on the reef. These rates can detect accretion signals when calcifying organisms, such as corals or algae, have grown on their exteriors. Rates of macroboring were determined by changes in the internal volume of the BMUs (e.g., that removed by bore holes) divided by the number of years the BMU was deployed on the reef. Macroboring can occur from eroders such as clionaid sponges, annelids and other macroboring fauna.

本数据集收录的侵蚀速率数据，来源于在威克岛、夏威夷群岛与马里亚纳群岛的现有长期监测站点回收的生物侵蚀监测单元（bioerosion monitoring unit, BMU），这些数据采集自由美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）太平洋岛屿渔业科学中心（Pacific Islands Fisheries Science Center, PIFSC）珊瑚礁生态系统项目（Coral Reef Ecosystem Program, CREP）主导的国家珊瑚礁监测计划（National Coral Reef Monitoring Program, NCRMP）科考任务。所有样本均在美国国家海洋和大气管理局大西洋海洋与气象实验室（Atlantic Oceanographic and Meteorological Laboratory, AOML）完成分析，作为美国国家海洋和大气管理局持续推进的NCRMP项目的一部分。BMU采用洁净的珊瑚骨骼制作，部署于珊瑚礁上的时长为3年。本数据集收录的是首批制作完成的BMU相关数据，因此当时制定的监测规程在后续不久即进行了修订，以更全面地反映生物侵蚀速率情况。早期分析流程采用台式微型计算机断层扫描仪（microCT，布鲁克（Bruker））完成部署前的初始扫描，而样本回收后的分析（包括本数据集收录的分析工作）则使用了更大尺寸的计算机断层扫描设备（CT扫描仪，西门子（Siemens））。

通过对BMU进行CT扫描，可以获取其密度、体积与质量的变化情况，以此评估生物侵蚀速率。基于本数据集，可以通过珊瑚礁结构体积损失量以及碳酸钙质量（单位：克）损失量，计算得到年度侵蚀速率与堆积速率。本数据集收录的堆积速率，通过计算BMU外表面附着的非原生碳酸盐物质的体积，再除以BMU在珊瑚礁上的部署时长得到。当珊瑚、藻类等钙化生物在BMU外部生长时，该方法可以检测到堆积速率信号。大型钻孔侵蚀速率则通过BMU内部体积的变化量（例如被钻孔通道移除的体积）除以BMU部署时长计算得到。大型钻孔侵蚀可由穿海绵（clionaid sponges）、环节动物（annelids）及其他大型钻孔动物等侵蚀生物引发。