1. Proliferative kidney disease (PKD) caused by the myxozoan parasite Tetracapsuloides bryosalmonae is an emerging salmonid disease implicated in recent declines in salmonid populations. Laboratory experiments have shown that the clinical symptoms of PKD exacerbate with increasing temperature. However, empirical evidence for a relationship between climate change and PKD driven declines in wild salmonid stocks is scarce.
2. The current study uses both empirical data and ecological niche modelling to extrapolate future changes in temperature and precipitation on the spread of PKD in relation to changes in suitability of rivers for its primary bryozoan and secondary salmonid hosts.
3. A 20‐year dataset on brown trout density using standardised method shows a decline of more than 50% in the population of the river Wutach, south‐western Germany at 536–755 m elevation. The decline coincides with higher prevalence of PKD. This decline was temperature related and driven by reduced local survival of parr to yearlings. Kidney hyperplasia was highest at low elevations and correlated negatively with trout density.
4. Niche models based on state‐wide data show strong overlap in the areas suitable for T. bryosalmonae and its primary bryozoan hosts, and a strong link with temperature. Projections based on moderate to high emission‐case climate change scenarios predict a 50%–82% decrease in the area suitable for salmonids within this century, linked to PKD.
5. The empirical data identify temperature‐mediated PKD as the underlying cause of the population decline. This relationship was corroborated by the niche modelling results. The highest losses are expected in projected salmonid suitable areas where salmonid habitats currently overlap with areas suitable for T. bryosalmonae.
6. With ongoing climate change, both current and future populations are at severe risk to T. bryosalmonae and its associated disease PKD. Conservation efforts of salmonid stocks are dependent on climate mitigation and measures to help salmonids adapt to the disease.

中文翻译：

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在预测的气候变化下，寄生性四环囊藻苔藓沙门氏菌（引起增生性肾脏疾病）对中欧鲑鱼种群的当前和预期影响

1. 由粘虫寄生虫四囊藻苔藓小单胞菌引起的增生性肾脏疾病（PKD）是一种新兴的鲑鱼病，与鲑鱼种群的近期减少有关。实验室实验表明，PKD的临床症状会随着温度的升高而加剧。但是，缺乏关于气候变化与公钥簿驱动的野生鲑鱼种群下降之间关系的经验证据。
2. 当前的研究使用经验数据和生态位模型来推断未来温度和降水变化对PKD扩散的影响，这与河流对其主要苔藓动物和次要鲑鱼宿主的适应性变化有关。
3. 使用标准化方法进行的20年褐鳟鳟鱼密度数据集显示，海拔536–755 m，德国西南部的Wutach河人口减少了50％以上。下降与PKD患病率较高相吻合。这种下降与温度有关，是由于幼鸽到一岁幼鸽的局部存活率降低。肾脏增生在低海拔时最高，与鳟鱼密度呈负相关。
4. 基于全州范围数据的生态位模型显示，在适合于苔藓沙门氏菌及其主要苔藓动物宿主的区域中存在强烈的重叠，并且与温度有着密切的联系。根据中度至高排放量气候变化情景的预测，与公钥簿相关的本世纪内适合鲑鱼的面积将减少50％至82％。
5. 经验数据确定温度介导的PKD是人口下降的根本原因。生态位建模结果证实了这种关系。预计在预计的鲑鱼适宜地区，其中鲑鱼栖息地目前与适于苔藓假单胞菌的地区重叠的地区，损失最大。
6. 随着气候变化的持续进行，当前和未来的人群都面临着苔藓沙门氏菌及其相关疾病PKD的严重威胁。鲑鱼种群的养护工作取决于气候减缓和帮助鲑鱼适应疾病的措施。