Data from: Stability of environmental DNA methylation and its utility in tracing spawning of fish

The use of environmental DNA (eDNA) as a new method of ecological
monitoring is widely applied. Although eDNA can provide important
information on the distribution and biomass of particular taxa, an
organism’s DNA sequences remain unaltered throughout its existence, which
complicates identifying crucial events, including reproduction, with high
accuracy. We thus examined DNA methylation as a novel source of
information from eDNA, considering that methylation patterns of eggs and
sperm released during reproduction differ from those of somatic tissues.
Despite its potential applications, little is known about eDNA
methylation, including its stability and methods for detection and
quantification. Therefore, we conducted tank experiments and performed
methylation analysis targeting 18S rDNA through bisulfite amplicon
sequencing. Methylation of eDNA was not affected by degradation and was
equivalent to the rate of genomic DNA from somatic tissues. Unmethylated
DNA, which is abundant in the ovary, was detected in eDNA during
reproductive activity of fish. These results indicate that eDNA
methylation is a stable signal reflecting genomic methylation and
demonstrate that germ cell-specific methylation patterns can be used as
markers for detecting reproductive activity.