Global biogeography of marine fungi is shaped by the environment

Fungi are essential components of marine ecosystems, yet very little is known about their global distribution and diversity in the marine environment. In this study, we analyzed marine fungal community structure at a global scale using the International Census of Marine Microbes dataset. Marine fungal communities sampled from both the water column and sediments were compared. Based on the sequences of the nuclear ribosomal small subunit V9 region, 2200 operational taxonomic units (OTUs) were identified at 97% similarity. There was a significant distinction between the pelagic and benthic communities, with 15.4% OTUs shared between the two realms. Environmental factors, particularly sample depth, oxygen, and nitrate, strongly correlated with the fungal community composition and explained more variance than did geographic distance. This study represents the first global-scale analysis of marine fungal community structure, and highlights potential opportunities for research in marine fungal ecology and biogeography.