Eawag Dübendorf Switzerland

1 Introduction Despite being frequently studied in isolation, aquatic and terrestrial communities are known to interact and establish combined aquatic-terrestrial food webs (McFadden et al. 2022), in which predators are key in underpinning the functions of both ecosystems and underlying services (e.g., pollination, herbivory, pest control; Knight et al. 2005; Wang and Brose 2018; Shipley et al. 2024).

1 INTRODUCTION River networks are universally characterized by a fractal signature, i.e., with each part being similar to the whole (Mandelbrot, 1983; Rodriguez-Iturbe & Rinaldo, 2001; Tarboton et al., 1988).

1 INTRODUCTION Environmental DNA (eDNA, i.e., DNA isolated from environmental samples; Pawlowski et al., 2020; Taberlet et al., 2012) has revolutionized ecological research, allowing for fast, cost-effective and taxonomically broad biodiversity assessments, especially in aquatic media (Beng & Corlett, 2020; Deiner et al., 2017; Thomsen & Willerslev, 2015; Valentini et al., 2016).