Multiple environmental changes are thought to be contributing to the widespread decline of amphibians in montane regions, but interactions between drivers of decline are not well understood. It has been proposed previously that elevated ultraviolet-B radiation (UBVR) and low temperatures may interact in their negative effects on health, immune function and disease susceptibility in exposed amphibians. In the present study, we chronically exposed larvae of the striped-marsh frog (Limnodynastes peronii) to a factorial combination of high and low UVBR and high and low temperature to assess interactive effects on growth, survival and indices of immune function. The high UVBR treatment reduced growth and survival of larvae compared to the low UVBR treatment at both temperatures, but the effects were significantly enhanced at low temperature. High UVBR exposure also induced a chronic inflammatory response as evidenced by an increase in the leucocyte proportion of total cells and altered the ratio of neutrophils to lymphocytes in the blood, highlighting a potential mechanistic basis for increased disease susceptibility in amphibians living at high altitudes. Our findings stress the importance of investigating environmental factors in combination when assessing their effects and highlight the mechanistic basis for how key environmental drivers in montane regions affect amphibian health. Continuation of this work is necessary for the development of targeted conservation strategies that tackle the root causes of montane amphibian declines.

中文翻译：

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紫外线B辐射对生理，免疫功能和存活的影响取决于温度：对两栖动物数量下降的影响。

人们认为，多种环境变化是造成山地地区两栖动物普遍下降的原因，但下降驱动因素之间的相互作用尚不十分清楚。先前已经提出，紫外线-B辐射（UBVR）升高和低温可能会对暴露的两栖动物的健康，免疫功能和疾病易感性产生负面影响。在本研究中，我们长期暴露了条纹沼泽青蛙的幼虫（Limnodynastes peronii）将高和低UVBR和高和低温的因子组合结合起来，以评估对生长，存活和免疫功能指标的相互作用。与低UVBR处理相比，高UVBR处理在两个温度下均降低了幼虫的生长和存活率，但在低温下效果显着增强。高UVBR暴露还诱导了慢性炎症反应，如血液中白细胞总数的增加和血液中嗜中性粒细胞与淋巴细胞比例的改变所证明的那样，这突显了生活在高海拔两栖动物中疾病易感性增加的潜在机理基础。我们的发现强调评估环境因素在评估其影响时的重要性，并强调了山区环境中主要环境驱动因素如何影响两栖动物健康的机制基础。继续开展这项工作对于制定有针对性的保护战略，以解决山地两栖动物数量减少的根本原因是必要的。