USING EDNA METABARCODING TO ASSESS INVERTEBRATE BIODIVERSITY OF EELGRASS (ZOSTERA MARINA) BEDS ACROSS NOVA SCOTIA

Abstract

Eelgrass (Zostera marina) beds are a common feature of Atlantic coastlines and represent diverse, productive marine communities that are highly valued for their ecosystem services. As near-shore communities, however, eelgrass beds are under threat from a host of anthropogenic factors and require regular monitoring to measure biodiversity levels and to track changes with time. Environmental DNA (eDNA) metabarcoding is a relatively new approach for monitoring aquatic biodiversity, yet its ability to provide a comprehensive assessment of invertebrate eelgrass communities relative to more standard methods (e.g., visual surveys/sediment cores) remains to be determined. In this study, eDNA cytochrome c oxidase subunit I (COI) metabarcoding was used to characterize invertebrate biodiversity in 17 eelgrass beds spanning the breadth of Nova Scotia, from Chebogue to Aspy Bay. Three 1L water samples and one field control collected at each site underwent eDNA extraction, PCR amplification, clean-up, and multiplexing before being sequenced for taxonomic assignment. Across the 17 sites, 168 invertebrate species were identified with a taxonomic probability assignment of >95%. Of the species reported, only 57 (34%) were detected in standard surveys. Conversely, 71 taxa historically recorded using standard methods were not found in eDNA analyses. eDNA was successful, however, in detecting 18 of the 23 most common invertebrate taxa based on published species records from 11 Nova Scotian eelgrass beds. While eDNA clearly represents an exciting new monitoring tool for eelgrass communities, further work is needed to establish the limitations of this approach in documenting species’ presence based on factors such as taxonomic affiliation, ecology (infaunal/epifaunal), body size, and abundance.