Ecology. 2014 Apr;95(4):845-55. doi: 10.1890/13-0916.1.
Anthropogenic climate change will present both opportunities and challenges for pool-breeding amphibians. Increased water temperature and accelerated drying may directly affect larval growth, development, and survival, yet the combined effects of these processes on larvae with future climate change remain poorly understood. Increased surface temperatures are projected to warm water and decrease water inputs, leading to earlier and faster wetland drying. So it is often assumed that larvae will experience negative synergistic impacts with combined warming and drying. However, an alternative hypothesis is that warming-induced increases in metabolic rate and aquatic resource availability might compensate for faster drying rates, generating antagonistic larval responses. We conducted a mesocosm experiment to test the individual and interactive effects of pool permanency (permanent vs. temporary) and water temperature (ambient vs. (+) -3 degrees C) on three anurans with fast-to-slow larval development rates (Great Basin spadefoot [Spea intermontana], Pacific chorus frog [Pseudacris regilla], and northern red-legged frog [Rana aurora]). We found that although tadpoles in warmed pools reached metamorphosis 15-17 days earlier, they did so with little cost (< 2 mm) to size, likely due to greater periphyton growth in warmed pools easing drying-induced resource competition. Warming and drying combined to act antagonistically on early growth (P = 0.06) and survival (P = 0.06), meaning the combined impact was less than the sum of the individual impacts. Warming and drying acted additively on time to and size at metamorphosis. These nonsynergistic impacts may result from cotolerance of larvae to warming and drying, as well as warming helping to offset negative impacts of drying. Our results indicate that combined pool warming and drying may not always be harmful for larval amphibians. However, they also demonstrate that antagonistic responses are difficult to predict, which poses a challenge to proactive conservation and management. Our study highlights the importance of considering the nature of multiple stressor interactions as amphibians are exposed to an increasing number of anthropogenic threats.
人为引起的气候变化将为池塘繁殖的两栖动物带来机遇和挑战。水温升高和干燥加速可能直接影响幼虫的生长、发育和存活，但对于未来气候变化下的幼虫，这些过程的综合影响仍知之甚少。预计地表温度升高将使水温升高并减少水的输入，导致湿地更早更快地干涸。因此，人们通常认为幼虫将受到变暖与干燥相结合的负面影响。然而，另一种假设是，变暖引起的代谢率升高和水生资源的增加可能会弥补更快的干燥速度，从而产生拮抗的幼虫反应。我们进行了一个中观实验，以测试池塘永久性（永久性与临时性）和水温（环境温度与升高 3 摄氏度）对具有快速到缓慢幼虫发育率的三种蛙类（大盆地锹形虫 [Spea intermontana]、太平洋蛙 [Pseudacris regilla] 和北红蛙 [Rana aurora]）的单独和相互作用的影响。我们发现，尽管温暖池塘中的蝌蚪提前 15-17 天达到变态期，但对体型的影响很小（<2 毫米），这可能是由于温暖池塘中的附着生物生长更多，缓解了干燥引起的资源竞争。变暖与干燥结合对早期生长（P = 0.06）和存活率（P = 0.06）产生拮抗作用，这意味着联合影响小于单个影响的总和。变暖与干燥对变态时间和大小的影响是相加的。这种非协同作用的影响可能是由于幼虫对变暖与干燥的共耐受，以及变暖有助于抵消干燥的负面影响。我们的研究结果表明，池塘变暖与干燥的综合影响对于幼虫两栖动物并不总是有害的。然而，它们也表明，拮抗反应难以预测，这对主动保护和管理构成了挑战。我们的研究强调了在两栖动物面临越来越多的人为威胁时，考虑多种胁迫因素相互作用的性质的重要性。
