Metagenomic analysis has unveiled the widespread presence of pelagic fungi in the global ocean, yet their quantitative contribution to carbon stocks remains elusive, hindering their incorporation into biogeochemical models. Here we revealed the biomass of oceanic fungi in the open ocean water column by combining ergosterol extraction, Calcofluor-White staining, CARD-FISH, and microfluidic mass sensor techniques. We compared fungal biomass to the biomass of other more studied microbial groups in the ocean such as archaea and bacteria. Globally, fungi contributed more biomass than archaea. Collectively, our findings reveal the important contribution of fungi to open ocean biomass and, consequently, the marine carbon cycle, emphasizing the need for their inclusion in biogeochemical models.
 

mycoplankton, ergosterol, oceanic fungi, CARD-FISH