Environmental DNA can be applied as a tool to detect low abundance organisms in both active and passive forms. Active eDNA surveys target individual species or groups of taxa for detection by using highly sensitive species-specific quantitative real-time PCR [27] or digital droplet PCR markers[28]. Passive eDNA surveys employ massively-parallel DNA sequencing to amplify all eDNA molecules in a sample with no a priori target in mind providing blanket DNA evidence of biotic community composition.[29]