The utility of a metagenomics approach for marine biomonitoring

The isolation and analysis of environmental DNA (eDNA) for ecosystem assessment and monitoring has become increasingly popular. A majority of studies have taken a metabarcoding approach—that is, amplifying and sequencing one or more gene targets of interest. Shotgun sequencing of eDNA—also called metagenomics—while popular in microbial community analysis has not seen much adoption for the analysis of other groups of organisms. Especially in light of the existence of extremely high-capacity DNA sequencers, we decided to test the performance of a shotgun approach side-by-side with a metabarcoding approach on marine water samples obtained from offshore Newfoundland. We found that metabarcoding remains the most efficient technique, but that metagenomics also has significant power to reveal biodiversity patterns, and in fact can be treated as an independent confirmation of ecological gradients. Moreover, we show that metagenomics can also be used to infer factors related to ecosystem health and function.