<b>Living in a multi-stressor world: nitrate pollution and thermal stress interact to affect amphibian larvae</b>

The interaction of widespread stressors such as nitrate pollution and increasing temperatures associated with climate change are likely to affect aquatic ectotherms such as amphibians. The metamorphic and physiological traits of amphibian larvae during the critical onset of metamorphosis are particularly susceptible to these stressors. We used a crossed experimental design subjecting <i>Rana temporaria </i>larvae to four constant rearing temperatures (18, 22, 26, 28 °C) crossed with three environmentally relevant nitrate concentrations (0, 50, 100 mg × L^-1) to investigate the interactive and individual effects of these stressors on metamorphic (i.e., growth and development) and physiological traits (i.e., metabolism and heat tolerance) at the onset of metamorphosis. Larvae exposed to elevated nitrate concentrations and thermal stress displayed increased metabolic rates but decreased developmental rate, highlighting interactive effects of these stressors. However, nitrate pollution alone had no effect on either metamorphic or physiological traits, suggesting that detoxification processes were sufficient to maintain homeostasis but not in combination with increased rearing temperatures. Furthermore, larvae exposed to nitrate displayed diminished abilities to exhibit temperature-induced plasticity in metamorphosis timing and heat tolerance, as well as reduced acclimation capacity in heat tolerance and an increased thermal sensitivity of metabolic rate to higher temperatures. These results highlight the importance of considering the exposure to multiple stressors when investigating how natural populations respond to global change.

诸如硝酸盐污染与气候变化相关的升温等广泛存在的胁迫因子，大概率会对两栖类等水生变温动物造成影响。两栖类幼体在变态关键启动阶段的变态与生理性状，对这类胁迫因子尤为敏感。本研究采用析因实验设计，将林蛙（*Rana temporaria*）幼体置于4种恒定饲养温度（18、22、26、28 ℃）与3种环境相关硝酸盐浓度（0、50、100 mg·L⁻¹）的交叉处理组中，以探究两类胁迫因子在变态启动阶段对变态相关性状（即生长与发育）及生理性状（即代谢速率与耐热性）的交互效应与独立效应。研究发现，暴露于高浓度硝酸盐与热胁迫的幼体，其代谢速率升高但发育速率降低，这凸显了两类胁迫因子的交互效应。然而，单独的硝酸盐污染对变态或生理性状均无显著影响，这表明机体的解毒过程足以维持内稳态，但在饲养温度升高的联合胁迫下则无法奏效。此外，暴露于硝酸盐环境的幼体，其变态时间与耐热性的温度诱导可塑性能力出现减弱，同时耐热性的驯化能力下降，且代谢速率对更高温度的热敏感性升高。本研究结果凸显了在探究自然种群如何响应全球变化时，考虑多重胁迫因子暴露的重要性。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于硝酸盐污染和热应激对两栖动物幼体的交互影响研究。通过交叉实验设计，考察了不同温度和硝酸盐浓度对Rana temporaria幼虫变态和生理特征的影响，发现交互作用导致代谢率升高但发育速率下降，而单独硝酸盐无显著效应。研究结果强调了多重应激因素在评估全球变化对自然种群影响中的重要性。