Re-analyses of relationships between size-fractioned eDNA and fish abundance
With regard to the size-fractionated eDNA (CX), the 95% CIs of the relative R2 values at the 0.8–3 µm size fraction were markedly lower than those at the >10 µm size fraction and did not include R2 = 1 (relative R2 = 0.389 [−0.026, 0.804]; Figure 3a). Linear mixed models displayed that theR2 values and slopes (i.e., the interaction between fish biomass and size fraction) were significantly lower at 0.8–3 µm than at >10 µm size fractions (both P< 0.01) (Tables 3a & 4a; Figures S1 & S2). On the one hand, regarding the upside-cumulative eDNA (UCX), the 95% CIs of the relative R2 values at the >3 µm size fraction were substantially higher than those at the >10 µm size fraction and without includingR2 = 1 (relative R 2 = 1.257 [1.020, 1.495]; Figure 3b). Additionally, linear mixed models showed that the R2 values were marginally higher at >3 µm than at >10 µm size fractions (P = 0.065) and the slope was slightly lower at >0.8 µm than at >10 µm size fractions (P = 0.090) (Tables 3b & 4b; Figures S3 & S4). On the other hand, regarding the downside-cumulative eDNA (DCX), the 95% CIs of the relative R2 values at the 0.4–3 µm size fraction were considerably lower than those at the >0.4 µm size fraction and did not include R2 = 1 (relative R2 = 0.587 [0.376, 0.797]; Figure 3c). The linear mixed models showed that the R2values were significantly lower at 0.4–3 µm than at >0.4 µm size fractions (P < 0.01), with no significant interactions between fish biomass and size fractions (Tables 3c & 4c; Figures S5 & S6).