With coral cover declining on most tropical reefs, efforts are intensifying to understand the mechanisms by which environmental stressors are driving populations into demographic deficit. Here, the population dynamics of sexual cohorts of small corals (≤ 4 cm diameter) in St. John, US Virgin Islands were used to test the hypothesis that the association of vital rates with environmental conditions has changed over 22 yr. The annual fate of 3999 corals at six sites and 7–9 m depth were used to populate Leslie Matrices and calculate assemblage growth rates (λ, without recruitment), mortality of the smallest corals, and graduation from the largest size class. Vital rates were tested for associations with temperature, the number of days with seawater warmer than 29.4°C (i.e., hot days), and rainfall. Transition probabilities varied among years, and usually more corals remained in their original size class than moved among size classes. Corals in the smallest size class had the highest mortality rate (42% yr⁻¹), λ had a grand mean of 0.688, and there were trends for λ to vary with the number of hot days and rainfall through quadratic relationships. The linear dependence of λ on rainfall over consecutive 3‐yr periods declined over two decades, suggesting that this colony size‐defined coral assemblage has undergone phenotypic change in their responsiveness to varying environmental conditions.

中文翻译：

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小珊瑚礁的生命率与气候变化有关

随着大多数热带礁石上珊瑚覆盖率的下降，人们正在加紧努力来了解环境压力源驱使人们陷入人口赤字的机制。在这里，美属维尔京群岛圣约翰的小珊瑚（≤4厘米直径）性种群的种群动态用于检验以下假设：生命率与环境条件之间的关系在22年内发生了变化。六个地点和7–9 m深度的3999条珊瑚每年的命运被用来填充Leslie矩阵并计算组合生长率（λ（无需招募），最小的珊瑚的死亡率以及从最大规格的珊瑚中毕业。测试了重要率与温度，海水温度高于29.4°C的天数（即高温）和降雨的相关性。过渡概率随年份的不同而变化，通常在原始大小级别中保留的珊瑚要多于在大小级别之间移动的珊瑚。最小尺寸类别的珊瑚具有最高的死亡率（42％yr ^-1），λ的平均平均值为0.688，并且λ的趋势随高温天数和降雨的二次关系而变化。λ的线性关系 连续三年的降雨量下降超过了二十年，这表明这种由群落大小决定的珊瑚组合在对变化的环境条件的响应能力方面已经发生了表型变化。