A University of Otago-led study has found evidence of a diverse community of microbes thriving in the cold, dark, low-energy environment beneath the Antarctic’s Ross Ice Shelf, hundreds of kilometres from the open ocean.
Study co-leader and Department of Microbiology and Immunology Associate Prof Sergio Morales said the microbes were completely isolated from the influence of the sun, which was normally central to sustaining oceanic life.
"These communities existing below the ice shelf must therefore rely on other energy sources to survive, but we didn’t know what those were until now.
"The activity of microbial communities like this are the foundation for all of Earth's ecosystems, so understanding life in this remote system helps make sense of life everywhere on Earth."
Prof Morales said the organisms were harvesting energy from a variety of sources, dominated by inorganic materials like ammonium, nitrite and sulphur compounds, but they also had the capacity to extract energy from organic sources.
"These organic compounds are themselves likely to be produced using energy from inorganic materials instead of the sun, since it can take years for water to complete its passage underneath the ice shelf.
"The really cool thing is that these under-ice communities are distinct to those in the open ocean, meaning it’s a hidden living world persisting in the absence of sunlight."
The area was accessed by using a hot water drilling system to bore through the 300m thick ice shelf.
University of Otago glaciologist and project leader Prof Christina Hulbe and University of Otago geologist Dr Christian Ohneiser contributed their expertise on ice and remote field operations, while Niwa oceanographer Dr Craig Stevens took measurements of conditions in the 700m-thick layer of ocean water beneath the floating ice.
Prof Hulbe said the new finding was the result of expertise provided by many institutions and he was thrilled to see everything coming together in the published research.
"Ice shelves are extensions of the ice sheet that push out from the continent, floating on the ocean, filling coastal bays and creating unique ice shelf ‘cavity’ environments that are very challenging to explore.
"These unique environments, the combination of big picture questions and fine scientific details, and the diverse team of experts that it takes to make sense of everything we measure, makes this work exciting, rewarding and important."
