Deep-sea waters are warming at an accelerating rate due to climate change, posing a significant threat to the delicate chemical and biological balance of our oceans. However, new research suggests that a surprisingly resilient group of microbes, Nitrosopumilus maritimus, may already be adapting to these changing conditions. These microscopic organisms, crucial to ocean nutrient cycles, could play a vital role in mitigating some of the impacts of a warming climate.
A study published in the Proceedings of the National Academy of Sciences details how these iron-dependent ammonia-oxidizing archaea are demonstrating an ability to thrive in warmer, nutrient-poor waters. Researchers predict that their adaptability will be key to reshaping the distribution of nutrients throughout the ocean, impacting the entire marine food web.
Nitrosopumilus maritimus and related species comprise approximately 30% of the marine microbial plankton population, making them essential drivers of chemical reactions that support marine life. Their ammonia-oxidizing activity is fundamental to the ocean’s nutrient cycling, influencing the growth of plankton – the foundation of the marine ecosystem – and sustaining biodiversity.
“Ocean-warming effects may extend to depths of 1,000 meters or more,” explains University of Illinois Urbana-Champaign microbiology professor Wei Qin. “We used to think that deeper waters were mostly insulated from surface warming, but now it is becoming clear that deep-sea warming can change how these abundant archaea use iron – a metal they depend on heavily – potentially affecting trace metal availability in the deep ocean.”
Microbial Adaptability to Warming Waters
The research, led by Professor Qin and University of Southern California global change biology professor David Hutchins, involved exposing a pure culture of Nitrosopumilus maritimus to varying temperatures and iron concentrations in controlled laboratory experiments. The team observed that increasing temperatures, coupled with limited iron availability, actually increased the microbes’ efficiency in utilizing iron. This suggests a remarkable capacity for acclimation to the stresses imposed by a changing climate.
“We coupled these findings with global ocean biogeochemical modeling by Alessandro Tagliabue from the University of Liverpool,” Qin said. “The results suggest that deep-ocean archaeal communities may maintain or even enhance their role in nitrogen cycling and primary production support across vast iron-limited regions in a warming climate.” This means these microbes may continue to effectively process nitrogen, even as conditions become more challenging.
Nitrosopumilus maritimus was first isolated from a tropical marine fish tank at the Seattle Aquarium, and is a chemolithoautotroph, meaning it gains energy from the oxidation of ammonia [2]. The cells are non-motile rods, measuring between 0.17-0.22μm in diameter, and 0.5-0.9μm in length [2].
Real-World Validation Underway
To validate these laboratory findings in a natural setting, Qin and Hutchins will co-lead a research expedition this summer aboard the research vessel Sikuliaq. The expedition will traverse from Seattle to the Gulf of Alaska, then south to the subtropical gyre, with a stop in Honolulu, Hawaii. A team of 20 researchers will join them to investigate the interactive effects of temperature and metal limitation on natural archaeal populations.
This follow-up research will build upon previous work demonstrating that Nitrosopumilus maritimus exhibits one of the highest substrate affinities for ammonia, allowing it to thrive even in extremely nutrient-poor environments [1]. Understanding these adaptations is crucial for predicting how marine ecosystems will respond to ongoing climate change.
The research was supported by the National Science Foundation, Simons Foundation, National Natural Science Foundation of China, University of Illinois Urbana-Champaign and the University of Oklahoma.
As ocean temperatures continue to rise, the ability of these microscopic organisms to adapt and maintain their vital functions offers a glimmer of hope for the health and resilience of marine ecosystems. Further research will be critical to fully understand the long-term implications of these findings and to inform strategies for mitigating the impacts of climate change on our oceans.
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Disclaimer: This article provides information for general knowledge and informational purposes only, and does not constitute medical advice. It is essential to consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.
