Environmental DNA (eDNA) detection is a valuable conservation tool that can be used to identify and monitor imperiled or invasive species and wildlife pathogens. Batrachochytrium pathogens are of global conservation concern because they are a leading cause of amphibian decline. While eDNA techniques have been used to detect Batrachochytrium DNA in the environment, a systematic comparison of extraction methods across environmental samples is lacking. In this study, we first compared eDNA extraction methods and found that a soil extraction kit (Qiagen PowerSoil) was the most effective for detecting Batrachochytrium dendrobatidis in water samples. The PowerSoil extraction had a minimum detection level of 100 zoospores and had a two- to four-fold higher detection probability than other commonly used extraction methods (e.g., QIAamp extraction, DNeasy+Qiashredder extraction method, respectively). Next, we used this extraction method on field-collected water and sediment samples and were able to detect pathogen DNA in both. While field-collected water filters were equivalent to amphibian skin swab samples in detecting the presence of pathogen DNA, the seasonal patterns in pathogen quantity were different between skin swabs and water samples. Detection rate was lowest in sediment samples. We also found that detection probability increases with the volume of water filtered. Our results indicate that water filter eDNA samples can be accurate in detecting pathogen presence at the habitat scale but their utility for quantifying pathogen loads in the environment appears limited. We suggest that eDNA techniques be used for early warning detection to guide animal sampling efforts.

环境DNA（eDNA）检测是一种有价值的保护工具，可用于识别和监视受威胁或入侵的物种和野生生物病原体。梭菌属病原体引起全球保护，因为它们是两栖动物数量下降的主要原因。尽管已使用eDNA技术检测环境中的拟南芥（Batrachochytrium） DNA，但缺乏对环境样品中提取方法的系统比较。在这项研究中，我们首先比较了eDNA提取方法，发现土壤提取试剂盒（Qiagen PowerSoil）是检测树枝状杆菌（Batrachochytrium dendrobatidis）的最有效方法。在水样中。与其他常用提取方法（例如分别为QIAamp提取，DNeasy + Qiashredder提取方法）相比，PowerSoil提取的最低检测水平为100个游动孢子，并且检测概率高出两倍至四倍。接下来，我们对野外采集的水和沉积物样品使用了这种提取方法，并且能够检测到两者中的病原体DNA。尽管现场收集的滤水器在检测病原体DNA方面与两栖类拭子样本相当，但拭子和水样本之间病原体数量的季节性模式有所不同。沉积物样品的检出率最低。我们还发现，检测概率随过滤水量的增加而增加。我们的结果表明，滤水器eDNA样品可以在栖息地规模上准确检测病原体的存在，但其用于量化环境中病原体负荷的效用似乎有限。我们建议将eDNA技术用于预警检测，以指导动物采样工作。