Conclusions
Targeting various fragment sizes of mitochondrial and nuclear genes of
Japanese jack mackerels, we showed that the addition of BAC suppressed
eDNA degradation and increased its initial concentration. In addition,
BAC enabled to maintain the number of marine fish species detected by
eDNA metabarcoding in seawater samples. Our study suggests the use of
BAC for the preservation of various types of eDNA from water samples
under various environmental conditions regardless of eDNA detection
strategies (i.e., species-specific or metabarcoding assay); accordingly,
we could increase the yield of target eDNA and the number of detected
species, which may prevent the underestimation of species abundance and
richness via eDNA analysis.
Some issues remain to be addressed in the future. First, all eDNA
studies using BAC have targeted fish and amphibians, and it is unknown
whether BAC effectively preserves eDNA released from other vertebrates
and invertebrates. Different production sources of eDNA among taxa might
lead to different performances of BAC in preserving aqueous eDNA. In
addition, understanding the interactions between BAC and environmental
factors is necessary. Takahara et al. (2020) reported a statistically
marginal interaction between BAC treatment and storage temperature on
eDNA yields. Further studies are required to determine the effects of
water chemistry and environmental conditions on the eDNA preservation
performance of BAC. Information on the performance of BAC, including
that revealed in this study, would simplify the application of eDNA
analysis in natural environments and enable the effective and precise
monitoring of biodiversity conservation and resource management.