Environmental Science and Studies Program, Towson University, Towson, MD, 21252, USA; Department of Environmental Toxicology, The Institute of Environmental and Human Health, Texas Tech University, Lubbock, TX, 79409, USA.
Environmental Science and Studies Program, Towson University, Towson, MD, 21252, USA; Department of Biological Sciences, Towson University, Towson, MD, 21252, USA.
Environ Pollut. 2020 Nov;266(Pt 1):115188. doi: 10.1016/j.envpol.2020.115188. Epub 2020 Jul 16.
A chemical contaminant of growing concern to freshwater aquatic organisms, including many amphibians, is chloride ion. The salinization of freshwater ecosystems is likely caused, in part, by the application of massive amounts of road de-icing salts to roadways during winter months. The issue of freshwater salinization has become the subject of many toxicity studies and is often investigated in conjunction with other chemical stressors. However, few published studies attempt to investigate the interactions of elevated chloride concentration and increased temperature. Further, no studies have investigated the gap between the recommended feeding conditions typically used in standard toxicity tests and those that may exist in natural amphibian habitats. This study addressed the critical issues of elevated chloride, increased temperature, and variation in food quality. We conducted a 96-h acute toxicity test to investigate acute chloride toxicity as impacted by different diets, as well as a chronic toxicity test to investigate the impacts of chloride, temperature, and resource quality on the survival and development of larval Lithobates sylvaticus (wood frogs). Chloride LCs ± 1 SE were 3769.22 ± 589.05, 2133.00 ± 185.95, and 2644.69 ± 209.73 mg Cl/L were for non-fed, low-protein diet, and high-protein diet, respectively. For the chronic toxicity study, elevated chloride decreased tadpole survival. Increased temperature, and lower resource quality, were found negatively impacted survival of tadpoles and altered time-to-metamorphosis. This study shows that environmentally relevant concentrations of chloride, temperatures, and the protein content of the diet all exert critical effects on larval wood frogs.
一种日益引起淡水水生生物（包括许多两栖动物）关注的化学污染物是氯离子。淡水生态系统的盐化部分可能是由于冬季大量使用道路除冰盐来处理道路造成的。淡水盐化问题已成为许多毒性研究的主题，并经常与其他化学胁迫因素一起进行调查。然而，很少有发表的研究试图调查氯化物浓度升高和温度升高之间的相互作用。此外，没有研究调查推荐的标准毒性测试中常用的摄食条件与自然两栖动物栖息地中可能存在的摄食条件之间的差距。本研究解决了氯化物升高、温度升高和食物质量变化等关键问题。我们进行了为期 96 小时的急性毒性试验，以研究不同饮食对急性氯化物毒性的影响，以及慢性毒性试验，以研究氯化物、温度和资源质量对 Lithobates sylvaticus （林蛙）幼虫存活和发育的影响。非摄食、低蛋白饮食和高蛋白饮食的氯化物 LC50 ± 1 SE 分别为 3769.22 ± 589.05、2133.00 ± 185.95 和 2644.69 ± 209.73 mg Cl/L。对于慢性毒性研究，升高的氯化物降低了蝌蚪的存活率。升高的温度和较低的资源质量被发现对蝌蚪的存活有负面影响，并改变了变态时间。本研究表明，环境相关浓度的氯化物、温度和饮食中的蛋白质含量都会对林蛙幼虫产生关键影响。
