Improvement of recovery yield of macro-organismal environmental DNA from seawater samples

In recent years, environmental DNA (eDNA) technology has been used in a variety of water environments. Environmental DNA concentrations in marine samples tend to be lower than those in freshwater samples, and few studies have explored methods to improve the recovery yields of eDNA from seawater samples. In this study, we compared different seawater preservation solutions (RNAlater or ATL) to improve eDNA yields. The eDNA concentrations of vertebrate and invertebrate species were compared using species-specific eDNA assays, and the number of detected fish and their compositions were compared using metabarcoding analysis. ATL treatment resulted in significantly higher eDNA yields for both vertebrate and invertebrate species than RNAlater treatment. Metabarcoding analysis revealed non-significant effects of preservation on the number of detected species and species composition. These results suggest that ATL treatment improves DNA yields without changing the species composition compared with the commonly used RNAlater treatment. The findings of this study will reduce false-negative outcomes and provide highly reliable results in future biological surveys. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s44211-023-00280-1.