Buck Julia C, Rohr Jason R, Blaustein Andrew R
Texas Research Institute for Environmental Studies, Sam Houston State University, Huntsville, TX, U.S.A.
Department of Integrative Biology, Oregon State University, Corvallis, OR, U.S.A.
Freshw Biol. 2016 Jan;61(1):110-120. doi: 10.1111/fwb.12685. Epub 2015 Sep 23.
Anthropogenic stressors may influence hosts and their pathogens directly or may alter host-pathogen dynamics indirectly through interactions with other species. For example, in aquatic ecosystems, eutrophication may be associated with increased or decreased disease risk. Conversely, pathogens can influence community structure and function and are increasingly recognised as important members of the ecological communities in which they exist.In outdoor mesocosms, we experimentally manipulated nutrients (nitrogen and phosphorus) and the presence of a fungal pathogen, (Bd), and examined the effects on Bd abundance on larval amphibian hosts (: Hylidae), amphibian traits and community dynamics. We predicted that resource supplementation would mitigate negative effects of Bd on tadpole growth and development and that indirect effects of treatments would propagate through the community.Nutrient additions caused changes in algal growth, which benefitted tadpoles through increased mass, development and survival. Bd-exposed tadpoles metamorphosed sooner than unexposed individuals, but their mass at metamorphosis was not affected by Bd exposure. We detected additive rather than interactive effects of nutrient supplementation and Bd in this experiment.Nutrient supplementation was not a significant predictor of infection load of larval amphibians. However, a structural equation model revealed that resource supplementation and exposure of amphibians to Bd altered the structure of the aquatic community. This is the first demonstration that sublethal effects of Bd on amphibians can alter aquatic community dynamics.
人为压力源可能直接影响宿主及其病原体，也可能通过与其他物种的相互作用间接改变宿主 - 病原体动态。例如，在水生生态系统中，富营养化可能与疾病风险的增加或降低有关。相反，病原体可以影响群落结构和功能，并且越来越被视为它们所存在的生态群落的重要成员。在室外中型生态系统中，我们通过实验操纵了养分（氮和磷）以及一种真菌病原体（蛙壶菌，Bd）的存在，并研究了其对两栖类幼虫宿主（雨蛙科）上Bd丰度、两栖动物特征和群落动态的影响。我们预测资源补充将减轻Bd对蝌蚪生长和发育的负面影响，并且处理的间接影响将在群落中传播。添加养分导致藻类生长发生变化，这通过增加体重、发育和存活率使蝌蚪受益。暴露于Bd的蝌蚪比未暴露的个体更早变态，但其变态时的体重不受Bd暴露的影响。在本实验中，我们检测到养分补充和Bd的相加效应而非交互效应。养分补充并不是两栖类幼虫感染负荷的显著预测因子。然而，结构方程模型表明，资源补充和两栖动物暴露于Bd改变了水生群落的结构。这是首次证明Bd对两栖动物的亚致死效应可改变水生群落动态。
