Statistical analysis
We performed Gaussian Type II regression models with the standardized major axis method to determine the relationship between the log10 eDNA abundances obtained from qSeq and dPCR analyses with the ”sma” function of the ”smatr” ver. 3.4.8 package in R ver. 3.6.0 (R Core Team, 2019). For the Gaussian Type II regression model, we ignored the zero values for the modelling. We employed the Gaussian Type II model because our preliminary evaluation found higher R2 values for Type II regression models with a Gaussian distribution than with a logarithmic distribution in all cases. We compared the differences in the coefficient values by overlapping the 95% confidence interval (CI) ranges.