National Coral Reef Monitoring Program: Water Chemistry of the Coral Reefs in American Samoa from Water Samples collected in 2015 (NCEI Accession 0157716)

Water samples are collected and analyzed to assess spatial and temporal variation in the seawater carbonate systems of coral reef ecosystems in the Hawaiian and Mariana Archipelagos, American Samoa, and the Pacific Remote Island Areas as part of the NOAA National Coral Reef Monitoring Program (NCRMP). Laboratory experiments reveal calcification rates of crustose coralline algae (CCA) are strongly correlated to seawater aragonite saturation state. Predictions of reduced coral calcification rates, due to ocean acidification, suggest that coral reef communities will undergo ecological phase shifts as calcifying organisms are negatively impacted by changing seawater chemistry. The data described here are from water samples collected at existing, long-term monitoring sites during NOAA Pacific Islands Fisheries Science Center (PIFSC), Coral Reef Ecosystem Program (CREP) led NCRMP mission around American Samoa in 2015. Two water samples are typically collected from each site—one at the reef and one at the surface directly above the reef—and a third sample may also be collected approximately 1 km offshore from the site. The samples are processed by CREP and sent to NOAA Pacific Marine Environmental Laboratory (PMEL) to be analyzed for total alkalinity (TA) and dissolved inorganic carbon (DIC). From these constituents, alongside temperature, salinity, and depth data, other constituents of the seawater carbonate system can be calculated. These monitoring data provide a baseline for tracking reef carbonate system changes due to globally increasing levels of atmospheric carbon dioxide.本数据集作为美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）国家珊瑚礁监测计划（National Coral Reef Monitoring Program, NCRMP）的一部分，通过采集并分析水样，以评估夏威夷群岛、马里亚纳群岛、美属萨摩亚以及太平洋偏远岛群的珊瑚礁生态系统中海水碳酸盐系统的时空变化特征。 实验室研究结果显示，结壳珊瑚藻（crustose coralline algae, CCA）的钙化速率与海水文石饱和度呈显著相关。因海洋酸化导致的珊瑚钙化速率降低的预测结果表明，随着钙化生物受到海水化学变化的负面影响，珊瑚礁群落将发生生态相转变。 本次所述数据集源自2015年美属萨摩亚周边，由美国国家海洋和大气管理局太平洋岛屿渔业科学中心（Pacific Islands Fisheries Science Center, PIFSC）珊瑚礁生态系统计划（Coral Reef Ecosystem Program, CREP）牵头实施的国家珊瑚礁监测计划科考任务中，采集自现有长期监测站点的水样。每个站点通常采集两份水样：一份取自礁体处，另一份取自礁体正上方的表层海水；部分站点还可额外采集第三份水样，采集位置距该站点约1公里的外海海域。采集的水样先由珊瑚礁生态系统计划进行预处理，随后送至美国国家海洋和大气管理局太平洋海洋环境实验室（Pacific Marine Environmental Laboratory, PMEL），开展总碱度（total alkalinity, TA）与溶解无机碳（dissolved inorganic carbon, DIC）的分析测试。结合上述检测得到的组分数据，以及温度、盐度与深度数据，可进一步计算得到海水碳酸盐系统的其他相关组分参数。本监测数据集可为追踪因全球大气二氧化碳浓度持续升高所引发的珊瑚礁碳酸盐系统变化提供基准参照。