Dissolved inorganic carbon, total alkalinity, nitrate, phosphate, temperature and other variables collected from time series observations at Heron Island Reef Flat from 2010-06-01 to 2010-12-13 (NCEI Accession 0127256)

This dataset contains carbonate chemistry and environmental parameters data that were collected from a 200-day time series monitoring on the Heron Island reef flat near the Great Barrier Reef. Understanding the temporal dynamics of present thermal and pH exposure on coral reefs is crucial for elucidating reef response to future global change. Diel ranges in temperature and carbonate chemistry parameters coupled with seasonal changes in the mean conditions define periods during the year when a reef habitat is exposed to anomalous thermal and/or pH exposure. In this study we define anomalous conditions as pH and temperature values that exceed a threshold that we have operationally defined for each variable. We present a 200-day time series from June through December 2010 of carbonate chemistry and environmental parameters measured on the Heron Island reef flat. These data reveal that aragonite saturation state, pH, and pCO2 were primarily modulated by biologically-driven, changes in dissolved organic carbon (DIC) and total alkalinity (TA), rather than salinity and temperature. The largest diel temperature ranges occurred in austral spring, in October (1.5 - 6.6 degrees Celsius) and lowest diel ranges (0.9 - 3.2 degrees Celsius) were observed in July, at the peak of winter. We observed large diel total pH variability, with a maximum range of 7.7 - 8.5 total pH units, with minimum diel average pH values occurring during spring and maximum during fall. As with many other reefs, the nighttime pH minima on the reef flat were far lower than pH values predicted for the open ocean by 2100. DIC and TA both increased from June (end of Fall) to December (end of Spring). Using this high-resolution dataset, we developed exposure metrics of pH and temperature individually for intensity, duration, and severity of low pH and high temperature events, as well as a combined metric. Periods of anomalous temperature and pH exposure were asynchronous on the Heron Island reef flat, which underlines the importance of understanding the dynamics of co-occurrence of multiple stressors on coastal ecosystems.

本数据集收录了大堡礁（Great Barrier Reef）附近赫伦岛礁坪（Heron Island reef flat）为期200天的时序监测所获取的碳酸盐化学与环境参数数据。明晰当前珊瑚礁所经历的热胁迫与pH暴露的时间动态，对于阐释珊瑚礁对未来全球变化的响应至关重要。温度与碳酸盐化学参数的昼夜波动范围，叠加平均状态的季节变化，共同界定了一年中礁生境遭遇异常热胁迫和/或pH暴露的时段。本研究将异常条件定义为超出我们针对各变量操作设定阈值的pH与温度数值。本研究提供了2010年6月至12月期间在赫伦岛礁坪开展监测得到的200天碳酸盐化学与环境参数时序数据集。这些数据显示，文石饱和状态（aragonite saturation state）、pH与pCO₂主要受生物驱动的溶解有机碳（DIC）与总碱度（TA）变化所调控，而非盐度与温度。最大的昼夜温度波动幅度出现在南半球春季的10月（1.5~6.6摄氏度），而最低的昼夜波动幅度则出现在冬季峰值的7月（0.9~3.2摄氏度）。研究观测到显著的昼夜总pH波动，最大波动范围为7.7~8.5个pH单位；昼夜平均pH的最小值出现在春季，最大值则出现在秋季。与众多其他珊瑚礁一样，赫伦岛礁坪的夜间pH最小值远低于截至2100年开放海域的预测pH值。DIC与TA均从6月（秋季末）升至12月（春季末）。依托这套高分辨率数据集，我们分别针对低pH与高温事件的强度、持续时长与严重程度，构建了pH与温度的暴露评估指标，同时也构建了综合评估指标。赫伦岛礁坪上的异常热胁迫与pH暴露时段并不同步，这凸显了明晰沿海生态系统多胁迫因子协同出现动态的重要性。