Bioconnection of airborne fungal diversity across the South Atlantic Ocean, sub-Antarctic and South Shetland Islands assessed using DNA metabarcoding

To better understand the long-distance dispersal of fungi between South America and Antarctica, we assessed aerial fungal diversity based on environmental DNA samples along a South Atlantic transect from Brazil to the South Shetland Islands, Antarctica using a metabarcoding approach. A total of 643,325 DNA reads were obtained across the latitudinal gradient, which was considered in five distinct sampling regions. The reads were assigned to 176 amplicon sequence variants representing the fungal phyla Ascomycota , Basidiomycota , Mortierellomycota and Chytridiomycota . Cladosporium sp. and Helotiales sp. were the most abundant assigned taxa overall, but they were restricted to the northern and central parts of the transect south to the Magellan Strait. Twelve fungal ASVs displayed intermediate abundance and 162 represented the minor components of the assigned diversity. The airborne fungal community displayed high indices of diversity, richness and moderate to low dominance. Diversity and taxa distribution changed across the five sampling areas. The most diverse fungal assemblages were detected along the South Atlantic coast of South America and the lowest diversity across the Drake Passage. Only Aspergillus versicolor , Chaetomiaceae sp., Fungal sp., Hanseniaspora sp., Malassezia restricta and Pichia kluyveri occurred across all five sampling areas. Very few taxa were shared between the South Atlantic region and the Antarctic Peninsula, suggesting a regional barrier between them. Most of the taxa detected were exclusive to the distinct sampling areas, suggesting that the high overall fungal diversity detected may reflect the changing environmental conditions and source land areas across latitudes. Ameliorating environmental conditions in the Antarctic Peninsula region may lead to increased probability that propagules that do arrive in Antarctica will be able to become established in Antarctic ecosystems. Further studies are necessary to understand the dispersal of fungal propagules to and within Antarctica.