Table 2.
Comparison of eDNA detection distances observed in caged fish experiments (Exp) or observational studies (Obs) and those predicted by simulation considering a value of the vertical transfer of FPOM from the water column to the riverbed (Vdep) computed from selected publications (median value ± interquartile range, see Supplementary Table 4) The maximal predicted detection distance is defined as the distance for which only one mtDNA copy of a hypothetical MOTU quantity released upstream is still present in the water column (see Method section for explanation).
| Reference | Method | DNA analysis | Waterflow (m3.s−1) | Wetted width (m) | Observed distance of detection | Predicted distance of detection (±Interquartile Q1–Q3) |
|---|---|---|---|---|---|---|
| Jane et al. (2015) | Exp | qPCR | 0.003 | 1.19 | >239.5 m | 128 m (54–283) |
| 0.031 | 3.35 | >239.5 m | 443 m (186–979) | |||
| Wilcox et al. (2016) | Exp | qPCR | 0.006 | 1.19 | 41 to 222 m | 235 m (98–518) |
| Exp | 0.010 | 3.35 | 72 to 1,459 m | 137 m (57–303) | ||
| Obs. | 0.059 | 2.88 | 100 to 900 m | 965 m (404–2131) | ||
| Civade et al. (2016) | Obs. | meta barcoding | 0.170 | 1.80 | 1.7 to 3.6 km | 4.5 km (1.9–9.9) |
| Deiner et Altermatt (2014) | Obs | qPCR | 3.520 | 14.00 | >9.1 km | 11.9 km (5–26.3) |
| 3.520 | 14.00 | >9.1 km | 12.8 km (5.4–28.3) | |||
| 3.790 | 14.00 | 1.6 to 9.1 km | 11.9 km (5–26.3) | |||
| This study | Obs | meta barcoding | 436.00 | 132.00 | 130.0 km (120.7–141.1) | 156.1 km (65.4–344.9) |
The water velocity (u) and the water depth (h) used to compute Sp and the maximal detection distance are approximated from the mean water flow (Q in m3) and the mean wetted width (w) considering a channel with a rectangular cross section.