Beneath a vast Antarctic ice floe, in a cathedral-like cave several hundred meters high, lie swarms of small shrimp-like creatures in a newly discovered underwater ecosystem that until recently had remained a secret locked by ice.

A team of New Zealand scientists discovered the ecosystem 500 meters below the ice in a suspected estuary, hundreds of kilometers from the edge of the Ross Ice Shelf.

Antarctica New Zealand has supported researchers from the Universities of Wellington, Auckland and Otago, the National Institute for Water and Atmospheric (Niwa) and Geological and Nuclear Sciences to investigate the role the estuary could play in climate-induced sea ice melt.

But as they drilled through the ice and into the river, their camera was invaded by amphipods, small creatures of the same lineage as lobsters, crabs and mites.

“For a moment we thought something was wrong with the camera, but when the focus improved we noticed a swarm of arthropods about 5mm in size,” Craig said. Stevens of Niwa.

Shrimp-like creatures in a newly discovered underwater ecosystem beneath the Ross Ice Shelf. Photography: NIWA/Craig Stevens

“We experimented in other parts of the pack ice and thought we had it under control, but this time some big surprises were thrown in.”

Although the work was driven by climate change, there was an element of discovery to the expedition, Stevens said.

“We were jumping up and down because all these animals swimming around our gear means there’s clearly an important ecosystem there.”

The Antarctic research site
The Antarctic research site. A network of hidden freshwater lakes and rivers lie beneath the ice caps. Photography: Niwa/Craig Stevens

Project leader Huw Horgan of Wellington’s Te Herenga Waka Victoria University was the first to spot the estuary, after spotting a groove in the ice while studying satellite imagery of the ice shelf Ross.

Researchers have known for some time about a network of freshwater lakes and rivers hidden beneath the Antarctic ice sheets, but they have yet to be directly studied, Horgan said.

“Getting and tasting this river was like being the first to enter a hidden world.”

Instruments had been left in the river to observe its behavior, he said, while lab researchers would study what makes the water unique.

The team’s findings went further: they had just deployed their mooring days before the huge eruption of Tonga’s Hunga Tonga-Hunga Ha’apai volcano. The team’s instruments detected a significant pressure change as the tsunami passed through the cavity.

Seeing the effects of the eruption reminded Stevens how connected the planet is. “We are here, in a forgotten corner of the world, seeing the real-time influences of events that felt to distant worlds. It was quite remarkable.