Dispersion and degradation of environmental DNA from caged fish in a marine environment

Abstract

Environmental DNA (eDNA) consists of DNA fragments shed from organisms into the environment, and can be used to identify species presence and abundance. This study aimed to reveal the dispersion and degradation processes of eDNA in the sea. Caged fish were set off the end of a pier in Maizuru Bay, the Sea of Japan, and their eDNA was traced at sampling stations located at the cage and 10, 30, 100, 300, 600 and 1000\xa0m distances from the cage along two transect lines. Sea surface water was collected at each station at 0, 2, 4, 8, 24 and 48\xa0h after setting the cage, and again after removing the cage. Quantitative PCR analyses using a species-specific primer and probe set revealed that the target DNA was detectable while the cage was present and for up to 1\xa0h after removing the cage, but not at 2\xa0h or later. Among the 57 amplified samples, 45 (79%) were collected within 30\xa0m from the cage. These results suggest that eDNA can provide a snapshot of organisms present in a coastal marine environment.