The bottom of the Southern Ocean's food chain has been found to be tough enough to survive rising temperatures.
Victoria University researchers have spent a decade studying how microalgae and bacteria which live in the bottom layers of Antarctic sea ice could be affected by climate change.
Andrew Martin said microbes made up 95 percent of the organic matter in the Southern Ocean and were crucial to the survival of many species.
"Unless you have a happy, healthy, solid foundation, there is not enough energy, there is not enough food, if you like, to support those top-level members of the food chain," Dr Martin said.
"So it's absolutely critical to have a thriving, microbial community."
The microbes survived in temperatures up to six times hotter than normal, the study showed.
However, the eventual loss of sea ice in a warmer future could scatter this essential food source into the ocean, taking it away from organisms such as krill, which feed on it, he said.