Assessing Metropolitan Biodiversity Using Aquatic Environmental DNA Metabarcoding

Abstract

In recent years, metropolitan areas are expanding faster than ever, largely affecting neighboring biodiversity and even forming an ecosystem of its own inhabited by often peculiar fauna and flora. Ongoing urbanization is known to affect the metropolitan biodiversity by altering the available habitats, causing biotic homogenization and introducing alien, often invasive species. Urban freshwater ecosystems are particularly vulnerable, and since all cities heavily rely on healthy aquatic ecosystems, further understanding and recognition of metropolitan freshwater biodiversity is key for sustainable planning and management of freshwater ecosystem services. Thus, we here showcase the potential of using DNA-based methods, in particular environmental DNA (eDNA) metabarcoding, i.e. a technique for biodiversity assessment from DNA traces in the environment, for assessing the metropolitan diversity and evaluating potential threats to healthy aquatic ecosystems. We present the advantages as well as the shortcomings of eDNA metabarcoding and by evaluating several studies, we discuss pathways for its future application in routine biomonitoring of metropolitan freshwaters (fig. 1) while at the same time also engaging city inhabitants. With that, we show that environmental DNA is a very capable tracer of environmental change in aquatic ecosystems and can be a promising solution for future sustainable development of metropolitan ecosystems.