Researchers on Australia's Antarctic icebreaker say some of the sea creatures they have been collecting could be new to science.
The RSV Nuyina is partway through a 60-day voyage to the edge of the icy continent — it's first mission dedicated solely to marine science.
The expedition is primarily focused on understanding the impact that warmer waters are having on the Denman Glacier, the fastest melting glacier in East Antarctica.
But the research teams are also collecting and analysing some of the unique biodiversity found in the Southern Ocean.
These include sea spiders "as big as your hand", sea stars "that grow to the size of a dinner plate" and octopus species endemic to the region, according to Professor Jan Strugnell, from James Cook University.
The specimens also include numerous "sea pigs", which are a type of sea cucumber already known to science, as well as small crustaceans that live on the sea floor, known as isopods.
"[We've collected] a really large diversity of a broad suite of marine life, and likely some new species to science," said Professor Strugnell, who is also part of the Securing Antarctica's Environmental Future research program.
A specially designed wet well on the vessel has also allowed researchers to capture tiny fragile creatures without damaging or destroying them.
One of them is a "sea butterfly", a type of sea snail that appears to flutter as it swims through the water.
The creature subsequently laid eggs in one of the ship's aquariums, providing researchers the chance to document pteropod egg development for the first time.
"The team is super excited about having the little creature and observing it and looking after it, so that it tells all the secrets that have been hidden until now," Dr Laura Herraiz Borreguero, from the CSIRO and Australian Antarctic Program Partnership (AAPP), said.
Close encounter with jade iceberg
The Nuyina left Hobart at the start of March, carrying 60 scientists from four Australian research organisations.
During its almost 4,000-kilometre journey, the research vessel has endured huge swells and gale force winds.
But on a calm day near the Shackleton ice shelf, scientists were able to observe the unusual sight of a jade-coloured iceberg.
Professor Delphine Lannuzel said while the snow and pure ice in most icebergs gave them a white and blue colour, it's hypothesised that jade icebergs get their green tone from high iron content.
"So those iron oxides are absorbing those blue lights, and that sort of makes that jade iceberg look [like] the colour that it is," Professor Lannuzel, from UTAS and the Australian Centre for Excellence in Antarctic Science, said.
"[The theory] hasn't been really tested yet, so we are hoping to do that one day."
'The system is changing'
Being close to the edge of the ice shelf has enabled seawater samples to be collected near the "tongue" of the Denman Glacier, which scientists say has retreated 5 kilometres over two decades.
The samples allow teams to analyse water temperature, salinity, oxygen levels and trace metals at different depths.
"For us to really understand how much heat enters the ice shelf, we need to be as close as possible to understand these processes and properties of the ocean," Dr Laura Herraiz Borreguero said.
The early results of the research had been surprising on two levels, she said.
"One is there's a really strong current right against the ice shelf, and we still don't know what that means for how much ocean heat gets into the ice shelf,"
she said.
"And at the same time, we've seen cooler waters that we were expecting at depth, and warmer waters within the midst of the water column, which could explain why we're seeing so little sea ice this season."
She said the voyage highlighted how critical it was for scientists to get access to the Antarctic region.
"The system is changing," she said.
"And it is really important that we observe the change so that we keep on challenging those climate models we rely on for our mitigation and adaptation strategies."
The ship will remain off the coast of Antarctica for about three more weeks, before returning to Hobart in early May.