Deep waters are warming due to heat waves and climate change, and this could spell trouble for the delicate chemical and biological balance of the oceans. However, a new study shows that the microbe Nitrosopumilus maritimus may already be adapting well to warmer, nutrient-poor waters. The researchers predict that these surprisingly adaptable iron-dependent ammonia-oxidizing archaea will play an important role in reshaping the ocean’s nutrient distribution in a changing climate.

The study’s findings are published in the Proceedings of the National Academy of Sciences.

Nitrosopumilus maritimus and its relatives make up about 30% of the marine microbial plankton population, and many researchers agree that the oceans depend on these microbes to drive the chemical reactions that support marine life. The ammonia-oxidizing activity of archaea makes them key players in ocean nutrient cycling. By altering the forms of nitrogen available in seawater, they control the growth of microbial plankton (the base of the marine food chain) and help maintain marine biodiversity.

“The effects of ocean warming may extend to depths of 1,000 meters or more,” said the University of Illinois at Urbana-Champaign. microbiology teacher weiqin. “We used to think that deeper waters were largely insulated from surface warming, but it is now becoming clear that deep-sea warming can change how these abundant archaea use iron, a metal they heavily depend on, potentially affecting the availability of trace metals in the deep ocean.”

The study, led by Qin and University of Southern California global change biology professor David Hutchins, used controlled trace metal cleanup experiments to expose a pure culture of Nitrosopumilus maritimus to a range of temperatures and iron concentrations. They observed that increasing temperature under iron-depleted conditions reduced the iron requirements of microbes and increased the physiological efficiency of iron use, demonstrating that microbes acclimate well to the stress of higher temperatures and lower iron availability.

“We coupled these findings with global ocean biogeochemical models conducted by Alessandro Tagliabue of the University of Liverpool,” Qin said. “The results suggest that deep ocean archaeal communities can maintain or even enhance their role in nitrogen cycling and supporting primary production in vast iron-limited regions in a warmer climate.”

This summer, Qin and Hutchins will serve as co-chief scientists aboard the research vessel Sikuliaq for a research expedition from Seattle to the Gulf of Alaska and then to the subtropical gyre, stopping in Honolulu, Hawaii. Qin will be joined by 20 other researchers whose goal will be to validate the new experimental findings in a real-world setting and focus on the interactive effects of temperature and metal limitation on natural populations of archaea.

Qin is also affiliated with the Carl R. Woese Institute for Genomic Biology.

The National Science Foundation, the Simons Foundation, the National Natural Science Foundation of China, the University of Illinois Urbana-Champaign, and the University of Oklahoma supported this research.