Do aquatic fungal environmental DNA assemblages reflect the surrounding terrestrial sporocarp communities?

The relationship between aquatic environmental DNA (eDNA) assemblages in rivers and the surrounding terrestrial fungal communities has been poorly investigated. Here, we focused on fungi that form soft sporocarps (soft fungi). Two years of sporocarp and aquatic eDNA sampling were conducted at a fragmented forest site, and the soft-fungal assemblages and their temporal dynamics were compared between these two sample types. Aquatic eDNA yielded approximately 1.5 times the operational taxonomic units (OTUs) compared to sporocarps and covered approximately half of the OTUs from sporocarp samples. Lineages that seldom form sporocarps or form inconspicuous sporocarps were successfully detected from aquatic eDNA. Although the OTU composition differed between sporocarp and aquatic eDNA, their temporal dynamics were similar, with both showing a 1-year periodicity. Aquatic eDNA provides insights into fungal diversity and temporal dynamics, but does not fully reflect terrestrial fungi diversity.