Instituto de Investigación en Recursos Cinegéticos CSIC-UCLM-JCCM, Ciudad Real, Spain.
Environ Toxicol Chem. 2011 Jun;30(6):1440-6. doi: 10.1002/etc.523. Epub 2011 Apr 2.
Agriculture-related pollution is among the major causes of global amphibian population declines. The multiple stressors to which amphibians are exposed in the field, such as predation pressure, can make agrochemicals far more deadly than when they act in isolation. Even within a small area, diffuse agricultural pollution does not affect all aquatic environments equally, which could account for local differences in amphibian sensitivity to agrochemicals. We examined the combined effects of ammonium nitrate fertilizer (0 to 45.2 mg N-NH 4(+)/L) and predator stress on larval Western spadefoot toad (Pelobates cultripes), using adult caged male marbled newts (Triturus marmoratus) as predators. We compared the interaction between both stressors in tadpoles from two ponds separated by 3 km. No significant mortality was observed (survival > 80% in all cases). Local differences were detected when analyzing larval growth, with a significant interaction between factors for one of the two populations tested (Fornillos de Fermoselle). Although tadpoles exposed to 45.2 mg N-NH 4(+)/L were 7% smaller than controls, the presence of predators from a foreign community resulted in animals 15% larger than those raised without predators after 15 d of experiment. Interestingly, predators from the same community as the tadpoles did not affect larval growth. The length of the tadpoles from a nearby location (Mámoles) was unaffected after exposure to ammonium nitrate and predatory stress.
农业相关的污染是全球两栖动物数量减少的主要原因之一。两栖动物在野外面临的多种胁迫因素，如捕食压力，会使农用化学品的杀伤力比单独作用时大得多。即使在小范围内，农业扩散污染也不会平等地影响所有水生环境，这可能是导致两栖动物对农用化学品敏感性存在局部差异的原因。我们使用成年笼养的大理石蝾螈（Triturus marmoratus）作为捕食者，研究了硝酸铵肥料（0 至 45.2mg N-NH₄(+)/L）和捕食压力对西部铲足蟾（Pelobates cultripes）幼体的综合影响。我们比较了来自相隔 3 公里的两个池塘的蝌蚪之间的两种胁迫因素之间的相互作用。在所有情况下，观察到的死亡率均不高（存活率均超过 80%）。当分析两个受测种群之一（Fornillos de Fermoselle）的幼虫生长时，检测到了本地差异，两个因素之间存在显著的相互作用。尽管暴露于 45.2mg N-NH₄(+)/L 的蝌蚪比对照组小 7%，但来自外来社区的捕食者会导致动物在 15 天的实验后比没有捕食者的对照组大 15%。有趣的是，与蝌蚪来自同一社区的捕食者不会影响幼体的生长。来自附近（Mámoles）的蝌蚪在暴露于硝酸铵和捕食压力后长度没有变化。
