A comparison of eDNA and community science as means of monitoring aquatic invertebrates in an urban ecosystem

Technological developments in the past decades have dramatically increased capacity for wildlife surveillance. As a result of rapidly evolving sequencing technologies, environmental DNA (eDNA) surveillance has become well established as a viable alternative to traditional sampling methods. Furthermore, the propagation of smart phone technology has made community-science biomonitoring efforts much more feasible. While community scientists have previously been recruited to assist in eDNA biomonitoring efforts, to our knowledge, there is little precedent for comparing eDNA results to observations from community scientists. To compare these two methods of biomonitoring, we used eDNA to document invertebrate biodiversity at 10 aquatic habitats (riverine and ponds) in urban Boise (Idaho, USA). We have also recruited volunteers to document the diversity of odonates in urban Boise through the app iNaturalist, and an organized odonate “bioblitz”. Although Odonates represent only a small portion of the invertebrates identified through eDNA sequencing, they are an important indicator species, and capture public attention, making them an ideal taxon for engaging the public. The Boise River watershed also represents an ideal system for such a study. It flows into the Boise metropolitan area in relatively pristine conditions, supports a high level of biodiversity, and is easily accessible to community scientists. Here, we discuss how these results compare, what they teach us about this urban riverine ecosystem, and the advantages and disadvantages of each approach.