Estimates of coral reef calcification and organic productivity provide valuable insight to community functionality and the response of an ecosystem to stress events. High-latitude coral reefs are expected to experience rapid changes in calcification rates and become refugia for tropical species following climate change and increasing bleaching events. Here, we estimate ecosystem-scale calcification and organic productivity at the world's southernmost coral reef using seawater carbon chemistry observations (Lord Howe Island, Australia). We reduce uncertainties in metabolic calculations by producing a detailed bathymetric model and deploying two current meters to refine residence time and volume estimates. Bathymetry-modelled transect depths ranged from 74% shallower to 20% deeper than depths averaged from reef crest/flat current meters, indicating that higher-resolution depth observations help to reduce uncertainties in reef metabolic calculations. Rates of ecosystem calcification were 56.6 ± 14.8 mmol m⁻² d⁻¹ in the winter and 125.3 ± 39.4 mmol m⁻² d⁻¹ in the summer. These rates are lower than most other high-latitude reefs according to our compilation of high-latitude coral ecosystem metabolism estimates. Coral cover ranged from 14.7 ± 2.3% in winter to 19.8 ± 2.1% in the summer. A concurrent bleaching event and cyclone occurred during summer sampling (February – March 2019), resulting in 47% of corals bleached at the study site and 2% mortality due to cyclonal damage. Therefore, it is likely that the summertime G_net rates underestimate baseline calcification. Our results enable future assessments of long-term change, but do not resolve the impact of bleaching at Lord Howe Island.

珊瑚礁钙化和有机生产力的估计值为社区功能以及生态系统对压力事件的响应提供了宝贵的见识。随着气候变化和漂白事件的增加，预计高纬度珊瑚礁的钙化速率会迅速变化，并成为热带物种的避难所。在这里，我们使用海水碳化学观测（澳大利亚豪勋爵岛）来估算世界最南端珊瑚礁的生态系统规模钙化和有机生产力。我们通过产生详细的测深模型并部署两个电流表来改善停留时间和体积估计，从而减少代谢计算的不确定性。测深模型所模拟的断面深度比礁顶/平流计的平均深度浅74％至深20％，表明高分辨率的深度观测有助于减少礁石代谢计算的不确定性。生态系统钙化速率为56.6±14.8 mmol·m^-2 ð ^-1在冬季和125.3±39.4毫摩尔米^-2 d ^-1在夏天。根据我们对高纬度珊瑚生态系统新陈代谢估计的汇编，这些比率低于大多数其他高纬度礁石。珊瑚覆盖率从冬季的14.7±2.3％到夏季的19.8±2.1％不等。在夏季采样（2019年2月至2019年3月）中，同时发生了漂白事件和旋风，导致研究地点的珊瑚发生了47％的漂白，而旋风造成的损害导致2％的死亡率。因此，夏季的G_净率很可能低估了基线钙化。我们的结果可以对未来的长期变化进行评估，但不能解决漂白现象对豪勋爵岛的影响。