Supplementary material from "Estimating transport and detectability of Chironex fleckeri eDNA in an open coastal bay "

Environmental DNA (eDNA) has emerged as a powerful tool for species detection and monitoring; however, understanding of its dispersion and transport dynamics and how this influences detectability is essential to enhance accuracy of eDNA use. A biophysical model was used to investigate the spatiotemporal dispersion of Chironex fleckeri eDNA in an open coastal bay, in northern Australia. The model revealed that local hydrodynamics, geomorphology, and meteorological conditions shaped ‘detection shadows’, with eDNA detectability constrained from hundreds of meters to kilometres from seeding locations. These dispersion estimates closely aligned with empirical detections of C. fleckeri medusae and polyps, demonstrating the utility of biophysical models for estimating eDNA transport and dispersal dynamics. The findings highlight the influence of eDNA decay and dilution on detectability and provide valuable insights for interpreting detections of targeted taxa. Here we demonstrate the broader potential of combining biophysical modelling with eDNA sampling.