U.S. Geological Survey, Northern Rocky Mountain Science Center, West Glacier, Montana, USA.
Department of Ecology, Montana State University, Bozeman, Montana, USA.
Glob Chang Biol. 2024 Jul;30(7):e17387. doi: 10.1111/gcb.17387.
Climate change is anticipated to cause species to shift their ranges upward and poleward, yet space for tracking suitable habitat conditions may be limited for range-restricted species at the highest elevations and latitudes of the globe. Consequently, range-restricted species inhabiting Arctic freshwater ecosystems, where global warming is most pronounced, face the challenge of coping with changing abiotic and biotic conditions or risk extinction. Here, we use an extensive fish community and environmental dataset for 1762 lakes sampled across Scandinavia (mid-1990s) to evaluate the climate vulnerability of Arctic char (Salvelinus alpinus), the world's most cold-adapted and northernly distributed freshwater fish. Machine learning models show that abiotic and biotic factors strongly predict the occurrence of Arctic char across the region with an overall accuracy of 89 percent. Arctic char is less likely to occur in lakes with warm summer temperatures, high dissolved organic carbon levels (i.e., browning), and presence of northern pike (Esox lucius). Importantly, climate warming impacts are moderated by habitat (i.e., lake area) and amplified by the presence of competitors and/or predators (i.e., northern pike). Climate warming projections under the RCP8.5 emission scenario indicate that 81% of extant populations are at high risk of extirpation by 2080. Highly vulnerable populations occur across their range, particularly near the southern range limit and at lower elevations, with potential refugia found in some mountainous and coastal regions. Our findings highlight that range shifts may give way to range contractions for this cold-water specialist, indicating the need for pro-active conservation and mitigation efforts to avoid the loss of Arctic freshwater biodiversity.
预计气候变化将导致物种向更高和更北的纬度和海拔迁移，但对于分布范围有限的物种而言，在全球最高海拔和纬度地区，跟踪适宜栖息地条件的空间可能有限。因此，栖息在全球变暖最明显的北极淡水生态系统中的分布范围有限的物种面临着应对生物和非生物条件变化或面临灭绝风险的挑战。在这里，我们使用了一个广泛的鱼类群落和环境数据集，该数据集涵盖了在斯堪的纳维亚半岛（上世纪 90 年代中期）采样的 1762 个湖泊，以评估北极茴鱼（Salvelinus alpinus）的气候脆弱性，北极茴鱼是世界上最耐寒和分布最北的淡水鱼类。机器学习模型表明，生物和非生物因素强烈预测了该地区北极茴鱼的出现，整体准确率为 89%。在夏季温度较高、溶解有机碳水平较高（即褐变）和存在北方狗鱼（Esox lucius）的湖泊中，北极茴鱼出现的可能性较小。重要的是，气候变暖的影响通过生境（即湖泊面积）得到缓和，同时被竞争物种和/或捕食者（即北方狗鱼）放大。在 RCP8.5 排放情景下的气候变暖预测表明，到 2080 年，81%的现存种群极有可能灭绝。在其分布范围内，特别是在南部分布范围的限制和较低的海拔地区，存在高度脆弱的种群，在一些山区和沿海地区可能存在避难所。我们的研究结果表明，对于这种冷水专家来说，可能会出现范围收缩而不是范围转移，这表明需要采取积极的保护和缓解措施，以避免北极淡水生物多样性的丧失。
