School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia; School of Ecosystem and Forest Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia.
School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia.
Ecotoxicol Environ Saf. 2018 Oct;161:482-488. doi: 10.1016/j.ecoenv.2018.06.028. Epub 2018 Jun 14.
Global declines in amphibian populations are a significant conservation concern, and environmental contamination is likely a contributing driver. Although direct toxicity may be partly responsible, contaminants are often present at sub-lethal concentrations in the wild. Behavioural end-points are becoming an increasingly useful method to estimate the impact of contaminants, particularly if the behavioural responses manifest to affect individual fitness (i.e. survival, growth, or reproduction). In the wild, most animals are affected by multiple stressors, and determining how these interact to affect behaviour is critical for understanding the ecological implications of contaminant exposure. Here, we examined the individual and interactive effect of the heavy metal copper and the insecticide imidacloprid on mortality rates and anti-predator behaviours of spotted marsh frog (Limnodynastes tasmaniensis) tadpoles. This common species frequently occupies and breeds in contaminated stormwater and agricultural wetlands, where copper and imidacloprid are often present. These contaminants may alter behaviour via physiological and neurological pathways, as well as affecting how tadpoles respond to chemical cues. Tadpoles suffered unexpectedly high mortality rates when exposed to imidacloprid concentrations well below published LC50 concentrations. Only unexposed tadpoles significantly avoided predator cues. Copper and imidacloprid reduced swimming speed and distance, and escape responses, while increasing erratic swimming. We observed an interactive effect of imidacloprid and copper on erratic swimming, but in general imidacloprid and copper did not act synergistically. Our results suggest that as contaminants enter waterbodies, tadpoles will suffer considerable direct mortality, reduced foraging capacity, and increased susceptibility to predation. Our results provide the first evidence of imidacloprid affecting amphibian behaviour, and highlight both the adverse effects of copper and imidacloprid, and the importance of exploring the effect of multiple contaminants simultaneously.
全球范围内的两栖动物种群数量下降是一个严重的保护问题，而环境污染很可能是一个促成因素。尽管直接毒性可能部分是原因，但污染物在野外通常以亚致死浓度存在。行为终点正成为一种越来越有用的方法来估计污染物的影响，特别是如果行为反应表现为影响个体的适应性（即生存、生长或繁殖）。在野外，大多数动物受到多种胁迫因素的影响，确定这些因素如何相互作用以影响行为对于理解污染物暴露对生态的影响至关重要。在这里，我们研究了重金属铜和杀虫剂噻虫啉对斑腿树蛙（Limnodynastes tasmaniensis）蝌蚪死亡率和防御行为的单独和交互影响。这种常见的物种经常在受污染的雨水和农业湿地中栖息和繁殖，而这些地方通常存在铜和噻虫啉。这些污染物可能通过生理和神经途径改变行为，以及影响蝌蚪对化学线索的反应。当暴露于低于公布的 LC50 浓度的噻虫啉浓度下时，蝌蚪遭受了意外的高死亡率。只有未暴露的蝌蚪明显避免了捕食者的线索。铜和噻虫啉降低了游泳速度和距离，以及逃避反应，同时增加了不稳定的游泳。我们观察到噻虫啉和铜对不稳定游泳的交互作用，但一般来说，噻虫啉和铜没有协同作用。我们的结果表明，随着污染物进入水体，蝌蚪将遭受相当大的直接死亡、觅食能力降低和对捕食的易感性增加。我们的结果首次提供了噻虫啉影响两栖动物行为的证据，并强调了铜和噻虫啉的不利影响，以及同时探索多种污染物影响的重要性。
