Arctic Fungi and the Carbon Cycle
Marine fungi play a hidden role in the global carbon cycle, according to a recent study published in PLOS Biology. Researchers focused on the seawater and sediments of Kongsfjorden, an Arctic fjord in Norway. While scientists previously assumed bacteria dominated the consumption of organic matter in these environments, new data suggests fungi are significant contributors to carbon storage.
Geomicrobiologist William Orsi of Ludwig Maximilian University of Munich reports that these fungi store carbon and nitrogen by incorporating dissolved amino acids into their own biomass. This process occurs in Arctic fjords, which are critical geological zones. These areas currently store more than 10 percent of all carbon buried beneath the seafloor. The study confirms that marine fungi process this organic matter with high efficiency.
Uncovering Microbial Contributions in Sediments
Lead author Juan Carlos Trejos-Espeleta and his team collected samples from glacial environments, tundra soils, and underwater sediments to map the activity of these microorganisms. The study identifies 80 distinct varieties of fungi within these sediment samples. Notably, 34 of these belong to the aquatic hyphomycetes group, specifically the genus Alatospora. These organisms thrive even in anoxic conditions, where oxygen levels are minimal just millimeters below the seafloor surface.
Research indicates that when fungi consume organic matter, the resulting carbon dioxide emissions are lower than when prokaryotes, such as bacteria, dominate the process. This suggests that the fungal presence helps lock carbon into the seafloor as solid biomass. Molecular mycoecologist Marlis Reich notes that these findings challenge the long-held paradigm that bacteria exclusively manage dissolved organic matter in marine ecosystems.
Future Implications for Climate Science
The discovery of active fungal populations in the deep seabed changes our understanding of marine ecosystems. Current data shows the fungi-to-prokaryote biomass ratio is higher on the seafloor than in neighboring tundra soils. This indicates that marine fungi are specialized for their environment and play a direct role in carbon sequestration.
Despite these findings, researchers emphasize that the Arctic environment is changing rapidly. Trejos-Espeleta warns that current efforts to monitor these ecosystems remain inadequate. Future climate models and carbon storage assessments must now account for the biological activity of fungi. As the Arctic warms, the stability of these carbon-trapping mechanisms becomes a subject of interest for environmental scientists tracking shifts in the global climate.