DISTRIBUTION OF ENVIRONMENTAL DNA IN RIVER CROSS SECTION AND DECOMPOSITION RATE DURING FLOWING-DOWN

Abstract

 Environmental DNA (eDNA) analysis is becoming widespread to reduce the effort for fish survey in fish friendly river works. However, the sampling method for obtaining a representative sample in cross-section, and eDNA flow-down distance are unknown. In this study, by performing metabarcoding analysis at 6 points per one cross-section, sampling method was examined. Then by performing the qMiFish method at 10 cross-sections in a river, cases of fish species detected upstream but not detected downstream were collected. Using these data, eDNA decomposition coefficient was determined, and flow-down distance was estimated. It was shown that to acquire a representative sample at a cross-section, sampling surface water at three points or more in a cross-section was necessary. eDNA decomposition coefficient was 3.55 [hr^-1], and the flow-down distance varied from 0.1 to 3.5 km depending on eDNA concentration and flow velocity.