Environmental DNA: A Preliminary Characterization of Invertebrate Biodiversity in a Sicilian River

Freshwater ecosystems are undergoing rapid species loss due to climate change and human impact. In this context, biomonitoring has become essential for species censusing and biodiversity conservation. In recent years, environmental DNA (eDNA) metabarcoding has emerged as a powerful, non-invasive alternative to traditional sampling and morphological identification methods. This study is the first to apply eDNA analysis to the characterization of invertebrate communities in the Oreto River, Sicily (Italy). Water samples were collected at three points of the river (upstream, midstream, downstream), and eDNA was extracted for metabarcoding. Overall, the analysis identified 40 species belonging to different phyla, including Annelida, Arthropoda, Cnidaria, Mollusca, Porifera and Rotifera. Twelve species appear to be newly recorded in Sicily, including confirmed identifications (Simulium trifasciatum, Rotaria rotatoria, Euchlanis dilatata, Lecane clostero-cerca) and other potential new identifications (Microchironomus tener, Micropsectra pallidula, Tinodes dives, Philodina flaviceps, Buchholzia appendiculata, Lecane bulla, Drosophila incompta, Corynoneura coronata). The study also confirmed the presence of alien species (Physella acuta, Craspedacusta sowerbii). Furthermore, species composition varied among the three sampling points, with most taxa detected in the upstream section. These results provide a preliminary snapshot of the biodiversity of river invertebrates, highlighting the potential of eDNA to complement traditional methods.