Fresh insights into Mediterranean biodiversity: Environmental DNA reveals spatio-temporal patterns of stream invertebrate communities on Sicily

Here, we present the first eDNA metabarcoding study from one stream catchment on Sicily, the largest Mediterranean island. We aimed to, aiming to i) investigate general diversity of macroinvertebrate communities across different stream sections, ii) assess seasonal changes in community composition, and iii) check if dispersal barriers can be identified. Water samples were taken at 27 different sampling sites in two seasons (autumn and winter 2019/2020) and eDNA metabarcoding performed using the mitochondrial cytochrome c oxidase subunit I (COI) gene. In total, we detected 98 macroinvertebrate species, including 28 taxa potentially new taxa for Sicily. By comparing Exact sequence variant (ESV) and species composition data showed, we observed that diversity differedwas generally different between seasons with less taxa detected in winter. We could also detected a dispersal barrier, which had a stronger effect on macroinvertebrate community structure in autumn. Our findings showindicate that eDNA metabarcoding provides valuable new information on Sicilian freshwater biodiversity through space and time, data going beyond descriptive species inventories. Thus, we encourage its application particularly for remote and understudied regions to provide a better understanding of the state and dynamics of freshwater biodiversity freshwater ecosystem functioning.