Researchers at Aarhus University have demonstrated that a simple adjustment to water filtration methods can dramatically improve the detection of marine animal DNA when using advanced, PCR-free sequencing. This methodological optimization could help clear a major bottleneck in aquatic biomonitoring and marine conservation efforts. The study is published in Metabarcoding and Metagenomics.

Over the past two decades, environmental DNA (eDNA) analysis has become a crucial tool for monitoring aquatic ecosystems. The most common method, metabarcoding, relies on PCR amplification of a smaller genetic region to identify specific taxa. However, PCR can lead to “significant taxonomic bias” because it often amplifies the DNA of different organisms unequally, making quantitative estimates difficult.

To avoid this, scientists have increasingly explored “shotgun sequencing”—a broad approach that sequences the DNA in a sample much more broadly—across the entire tree of life and across the genome.