Wood Liza, Welch Allison M
Department of Biology, College of Charleston, Charleston, South Carolina, USA.
Environ Toxicol Chem. 2015 Mar;34(3):667-76. doi: 10.1002/etc.2861. Epub 2015 Jan 30.
Because habitats are increasingly exposed to multiple stressors simultaneously, assessing the interactive effects of stressors is crucial for understanding how populations respond to human-altered habitats. Salinization of freshwater habitats is increasing and has the potential to interact with other stressors. Chemical pollutants also contribute to habitat degradation in freshwater environments, and both salinity and various pesticides can harm amphibians. The present study used a factorial experiment to investigate the effect of elevated salinity alone and in combination with each of 3 pesticides-atrazine, carbaryl, and glyphosate-on life history and behavior of southern toad larvae (Anaxyrus terrestris). Tadpoles were negatively affected by elevated salinity and by exposure to the insecticide carbaryl, with the most deleterious outcomes associated with both stressors combined. Carbaryl exposure led to reduced survival as well as sublethal effects on growth, activity and feeding behavior, escape response swimming, and time to metamorphosis. Tadpoles reared at elevated salinity were also smaller and less active, and ultimately metamorphosed later and at smaller size. Together, carbaryl and elevated salinity had a synergistic effect, resulting in particularly poor growth, depressed activity and feeding, and sluggish escape swimming among tadpoles exposed to both stressors simultaneously. These results suggest that both elevated salinity and carbaryl represent threats for amphibian populations and that pesticide exposure in salinized habitats may pose a particularly high risk.
由于栖息地越来越多地同时受到多种压力源的影响，评估压力源的交互作用对于理解种群如何应对人类改变的栖息地至关重要。淡水栖息地的盐碱化正在加剧，并且有可能与其他压力源相互作用。化学污染物也会导致淡水环境中的栖息地退化，盐分和各种农药都会对两栖动物造成伤害。本研究采用析因实验，调查了盐度升高单独以及与三种农药（阿特拉津、西维因和草甘膦）中的每一种联合使用时，对南方蟾蜍幼体（地蟾蜍）生活史和行为的影响。蝌蚪受到盐度升高和接触杀虫剂西维因的负面影响，两种压力源共同作用时产生的有害结果最为严重。接触西维因导致存活率降低，以及对生长、活动和摄食行为、逃避反应游泳和变态时间产生亚致死效应。在盐度升高环境中饲养的蝌蚪也更小、活动更少，最终变态时间更晚且体型更小。西维因和盐度升高共同产生了协同效应，导致同时受到两种压力源影响的蝌蚪生长特别差、活动和摄食受到抑制，逃避游泳迟缓。这些结果表明，盐度升高和西维因都对两栖动物种群构成威胁，并且在盐碱化栖息地接触农药可能带来特别高的风险。
