Rhodoliths built by crustose coralline algae (CCA) are ecosystem engineers of global importance. In the Arctic photic zone, their three‐dimensional growth emulates the habitat complexity of coral reefs but with a far slower growth rate, growing at micrometers per year rather than millimeters. While climate change is known to exert various impacts on the CCA's calcite skeleton, including geochemical and structural alterations, field observations of net growth over decade‐long timescales are lacking. Here, we use a temporally explicit model to show that rising ocean temperatures over nearly 100 years were associated with reduced rhodolith growth at different depths in the Arctic. Over the past 90 years, the median growth rate was 85 μm year−1 but each °C increase in summer seawater temperature decreased growth by a mean of 8.9 μm (95% confidence intervals = 1.32–16.60 μm °C−1, p < .05). The decrease was expressed for rhodolith occurrences in 11 and 27 m water depth but not at 46 m, also having the shortest time series (1991–2015). Although increasing temperatures can spur plant growth, we suggest anthropogenic climate change has either exceeded the population thermal optimum for these CCA, or synergistic effects of warming, ocean acidification, and/or increasing turbidity impair rhodolith growth. Rhodoliths built by calcitic CCA are important habitat providers worldwide, so decreased growth would lead to yet another facet of anthropogenic habitat loss.

中文翻译：

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与北极气候变化相关的原位红石生长减少

由壳状珊瑚藻 (CCA) 形成的红石是具有全球重要性的生态系统工程师。在北极光区，它们的三维生长模仿了珊瑚礁的栖息地复杂性，但生长速度要慢得多，每年生长微米而不是毫米。虽然已知气候变化会对 CCA 的方解石骨架产生各种影响，包括地球化学和结构变化，但缺乏对长达十年时间尺度的净增长的现场观察。在这里，我们使用时间显式模型来表明近 100 年来海洋温度的上升与北极不同深度红宝石生长的减少有关。过去90年，中位增长率为每年85微米−1但夏季海水温度每升高 1°C，生长速度平均就会降低 8.9 μm（95% 置信区间 = 1.32–16.60 μm °C）−1,p< .05)。 11 和 27 m 水深的红石榴石出现量有所减少，但 46 m 水深则不然，时间序列也最短（1991-2015 年）。尽管温度升高可以刺激植物生长，但我们认为人为气候变化要么超过了这些CCA的种群温度最佳值，要么变暖、海洋酸化和/或浊度增加的协同效应损害了红石榴的生长。由方解石 CCA 建造的红石是全世界重要的栖息地提供者，因此生长减少将导致人为栖息地丧失的另一个方面。