| The detected pattern of environmental DNA (eDNA) in a river channel derived from unnatural marine fishes wasverified by a regular interval metabarcoding (MB) assay to estimate the detectable range of eDNA-containingsubstances. Water samples were collected from 82 points in the Kumozu River, Mie, at 0.2 km intervalsfrom the rivermouth to 16.2 km. In the MB assay, 30/364 organizational taxonomic units (OTUs) of marine fishes, including twomigratory fishes that do not live in the Kumozu River. The 30 OTUs were detected at 246 points and were dividedinto 74 clusters consisting of 1-28 points based on the continuity of the detection points. According to the frequencydistribution, 5 clusters containing more than 11 points (> 2.2 km) were excluded as outliers, and 69 clusters of 1?8points (0.2-1.6 km) were selected as the significant range (p < 0.01) based on the Smirnov?Grubbs test. Thus, thedetectable range of an eDNA-containing substance from a single source is about 1.6 km in the lower reaches of theriver. However, if a remarkable source exists upstream, the range would extend several kilometers. |
