Wetland plant communities are changing rapidly due to a wide range of human activities. The deposition of leaf litter from novel plant communities can alter both the chemical and physical habitat of aquatic ecosystems. Lesser understood are the ecological consequences of novel leaf litter inputs in aquatic communities. Toward this goal, we used two plant invasion scenarios (comparing native black huckleberry to exotic autumn olive and native swamp loosestrife to exotic purple loosestrife) to simulate a shift in wetland plant communities. In this study, we investigated the effects of novel leaf litter leachates on three aquatic ecological interactions: intraspecific competition, predation and parasitism. We examined how leaf litter leachates influence the interactions of American toad larvae (Anaxyrus americanus) with their conspecifics, a dragonfly predator (Anax spp.) and a trematode parasite (Echinostomatidae). We found that leaf litter type influenced competitive interactions only for the huckleberry versus autumn olive comparison. We did not detect any effects of leaf litter type on predator–prey interactions. Finally, litter type strongly influenced host–parasite interactions for both leaf litter comparisons, altering host susceptibility, parasite survival and net infection rates. These results highlight the breadth of potential ecological repercussions of shifting wetland plant communities for native ecosystems.

由于广泛的人类活动，湿地植物群落正在迅速变化。来自新植物群落的落叶沉积可以改变水生生态系统的化学和物理栖息地。鲜为人知的是水生群落中新型落叶物输入的生态后果。为实现这一目标，我们使用了两种植物入侵场景（将本地黑越橘与异国情调的秋季橄榄以及本地沼泽珍珠菜与异国情调的紫色珍珠菜进行比较）来模拟湿地植物群落的转变。在这项研究中，我们调查了新型落叶物渗滤液对三种水生生态相互作用的影响：种内竞争、捕食和寄生。我们研究了落叶垃圾渗滤液如何影响美洲蟾蜍幼虫 ( Anaxyrus americanus)的相互作用) 与它们的同类，蜻蜓捕食者 ( Anax spp. ) 和吸虫寄生虫 (Echinostomatidae)。我们发现落叶类型仅对越橘与秋季橄榄比较影响竞争性相互作用。我们没有检测到落叶类型对捕食者-猎物相互作用的任何影响。最后，凋落物类型强烈影响两种叶凋落物比较的宿主 - 寄生虫相互作用，改变宿主易感性、寄生虫存活率和净感染率。这些结果突出了湿地植物群落迁移对本地生态系统的潜在生态影响的广度。