Assessing Invertebrate Biodiversity in Marine Eelgrass Beds in Nova Scotia

Eelgrass (Zostera marina) meadows are a common feature of marine coastlines, and are highly valued for their ecosystem services. These ecosystems are however threatened by climate change, disease, and human activities, and as such are of significant conservation interest. In order to monitor this widespread habitat, environmental DNA metabarcoding can be used to identify animals and other organisms that live within eelgrass beds. In this study, we use apply metabarcoding of the COI marker from eDNA samples taken from 17 eelgrass beds across Nova Scotia, Canada. eDNA samples were extracted from 0.22um filters, and sequenced on an Illumina MiSeq platform. We identified over 160 invertebrate species inhabiting eelgrass beds from Nova Scotia's south coast to Cape Breton, including several invasive species. We find that eDNA detects the majority of the most common invertebrates recorded in eelgrass beds by visual surveys, and show a significant decline in species richness with latitude in our study area. Our results reinforce using eDNA as a biomonitoring tool in the marine coastal zone, which can reveal the richness of animals living in these important habitats and emphasise their importance to the general public and stakeholders. Further investigation of the impacts of tides, time of day, and water volume filtered should be undertaken to develop a best-practice for monitoring eelgrass beds in Canada.