The rise in ocean temperatures, linked to marine heatwaves and climate change, is affecting deep-sea layers, raising concerns about potential disruptions to the ocean’s chemical and biological processes. Recent studies show that the marine microbe Nitrosopumilus maritimus can adapt to warmer, nutrient-poor conditions. These microorganisms, which depend on iron and are involved in ammonia oxidation, could significantly influence the distribution of nutrients in the oceans as climate change continues.

The Role of Nitrosopumilus maritimus in Ocean Ecosystems

Nitrosopumilus maritimus and related microbes make up about 30% of marine microbial plankton. They play a crucial role in ocean chemistry by initiating reactions that sustain marine ecosystems. These archaea carry out ammonia oxidation—a key process in the ocean’s nitrogen cycle. By converting nitrogen into various chemical forms, these microbes regulate the growth of microbial plankton, which forms the foundation of the marine food web. Thus, the activity of ammonia-oxidizing archaea helps maintain ocean biodiversity.

The Impact of Warming on Deep-Sea Layers

Ocean warming now extends to depths of 1,000 meters and beyond. It was once believed that deep waters were isolated from surface temperature changes, but new data indicate that warming at depth can alter how archaea use iron, affecting the availability of trace elements in deep-sea regions.

Experimental Studies on Microbial Adaptation

A research team conducted controlled experiments with pure cultures of Nitrosopumilus maritimus, exposing them to different temperatures and iron levels. The results showed that at higher temperatures and under iron-limited conditions, the microbes required less iron and used it more efficiently. This suggests that these organisms can adjust their metabolism to adapt to changing environmental conditions.

Modeling and Projections

The experimental data were integrated with global ocean biogeochemical models. Modeling showed that deep-sea archaeal communities may maintain or even increase their role in the nitrogen cycle and support primary production in low-iron regions as the climate warms.

Future Research

This summer, a scientific expedition is planned aboard the research vessel Sikuliaq, traveling from Seattle to the Gulf of Alaska and on to the subtropical gyre with a stop in Honolulu, Hawaii. Around 20 researchers will participate, studying natural populations of archaea in the ocean. The goal is to confirm experimental findings in natural settings and gain a deeper understanding of how changes in temperature and metal availability affect microbial activity in the deep ocean.