Positive effect of filtration additives for increasing environmental DNA detections in summer and winter oceanic waters

Abstract Environmental DNA (eDNA) is a convenient biodiversity monitoring tool, and many studies have focused on river coastal areas, while deep‐water oceanic surveys are rare. However, using eDNA techniques to learn about communities may also be useful approach. We tested methods enhance ocean collections adding four different materials (sediment, diatomite, zirconia bead, molecular sieve) in combination with 0.45‐μm pore size filter, compared 0.22‐μm five 2‐L volume replicates. The experiments were conducted off the Pacific coast of Hokkaido, Japan, summer winter. winter trial included larger water (10 L, duplicate) experimental treatment. added diatomite showed highest number detected operational taxonomic units (OTU) trial, sediment beads higher numbers GLM analysis that does not affect OTUs, season other additive significant effects. likely trapped more prevented it from passing through filters. 10‐L filtered sample had OTUs than combining replicates samples. Comparison among same revealed composition variable, species differed even sample. Species richness diversity summer, compositions between seasons. greater filtration additives suggest these could for surveys.