Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA.
Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA.
Environ Pollut. 2022 Dec 15;315:120349. doi: 10.1016/j.envpol.2022.120349. Epub 2022 Oct 4.
Road deicing salts are frequently used in northern regions of the world during the winter and early spring months. As a result, a significant portion of road runoff into surrounding aquatic habitats contains road deicing salts. Previous studies found road salt contaminations in vernal pools that pond-breeding amphibians commonly use, including spotted salamanders (Ambystoma maculatum) and wood frogs (Lithobates sylvaticus). Studies have examined the impact of road salt on both amphibian species, but to our knowledge no previous studies have examined how road salt impacts the interspecific competition between both amphibians. We hypothesized that road salt would negatively impact growth and survivorship of both amphibian species. During the spring and summer of 2017, we conducted an outdoor mesocosm experiment in which we created eight experimental conditions with three main factors: presence/absence of NaCl (1000 mg/L Cl), presence/absence of interspecific competition between the two amphibian species (A. maculatum and L. sylvaticus), and presence/absence of predatory dragonfly larvae (Family Libellulidae). Our experiment revealed that salt delayed hatching and increased deformity in spotted salamander hatchlings. Additionally, salt reduced salamander survivorship by 62% and frog survivorship by 30%. Wood frog tadpoles and road salt interacted to diminish salamander survivorship a further 80% beyond salt alone, likely through an increase in interspecific competition. Road salt increased the larval period of salamanders and decreased the proportion metamorphosed by the end of the experiment. Dragonfly larvae reduced salamander survivorship by 35%, whereas they increased wood frog tadpole development rates. Dragonfly larvae and salt interacted to alter tadpole denticle size, with salt negating the impact of dragonfly larvae. Thus, we found that salt interfered with aquatic predatory chemical cues. Overall, the results of this study suggest that management strategies should be implemented in order to reduce the impact of road salts on freshwater aquatic ecosystems.
道路除冰盐在世界北部地区的冬季和早春季节经常被使用。因此，大量进入周围水生栖息地的道路径流含有道路除冰盐。先前的研究发现，在春池（pond-breeding amphibians 常见的池塘）中存在道路盐污染，包括斑点钝口螈（Ambystoma maculatum）和林蛙（Lithobates sylvaticus）。研究已经检查了道路盐对这两个两栖物种的影响，但据我们所知，以前没有研究检查道路盐对这两个两栖物种之间种间竞争的影响。我们假设道路盐会对这两个两栖物种的生长和存活率产生负面影响。在 2017 年的春季和夏季，我们进行了一项户外中尺度实验，在该实验中，我们创建了八个实验条件，三个主要因素：存在/不存在 NaCl（1000mg/L Cl），存在/不存在两个两栖物种（斑点钝口螈和林蛙）之间的种间竞争，以及存在/不存在蜻蜓幼虫（蜻蜓科）的捕食。我们的实验表明，盐会延迟斑点钝口螈幼体的孵化并增加畸形。此外，盐使蝾螈的存活率降低了 62%，青蛙的存活率降低了 30%。林蛙蝌蚪和盐相互作用，使蝾螈的存活率进一步降低了 80%，这可能是由于种间竞争加剧。道路盐延长了蝾螈的幼虫期，并减少了实验结束时变态的比例。蜻蜓幼虫使蝾螈的存活率降低了 35%，而增加了林蛙蝌蚪的发育速度。蜻蜓幼虫和盐相互作用改变了蝌蚪的齿状突起大小，而盐则消除了蜻蜓幼虫的影响。因此，我们发现盐干扰了水生捕食化学线索。总的来说，这项研究的结果表明，应该实施管理策略，以减少道路盐对淡水水生生态系统的影响。
