Sailing in the wake of Scott and Shackleton to protect the warming Antarctic

Trapped in a ring of ice thousands of miles from home, some people might begin to question their choices.

But that’s not the case for Dr Hugh Carter. The expert in the echinoderms – the group which contains sea cucumbers, starfish, sea urchins and their relatives – was staying remarkably calm as approaching ice threatened to send his ship to the bottom of the sea.

“We’d been forced to take shelter from a storm in Robertson Bay, but as we went in our ice pilot became concerned about how much ice there was in front of us,” Hugh recalls. “He told the ship to turn around, but by the time we had the sea had been closed off behind us. We were trapped in an isolated pocket of ocean.”

“Some people were worried, but I must admit I was having a great time! I was really caught up in the excitement of being on an Antarctic expedition. Fortunately, we were able to nudge our way out through the newly formed ice and escape back into the open ocean.”

As a scientist on an Antarctic voyage, Hugh was following in the footsteps of scientists who had been part of major expeditions during the ‘Heroic Age’ of Antarctic exploration such as Edward Wilson and Dr George Murray Levick. The specimens they collected still reside in museums around the world, providing a rare snapshot of the continent during the twentieth century.

Since then, rising levels of pollution, greenhouse gases and habitat damage have reshaped our world, and Antarctica is no exception. During the ACTUATE voyage, Hugh was part of a team that set out from New Zealand to find out how the world’s most southerly continent was changing.

Crossing boundaries

The expedition set sail aboard the RV Tangaroa in mid-January to begin the first leg of its journey from Wellington, New Zealand, to Wood Bay on Antarctica’s Ross Sea coastline. After passing out of Wellington’s natural harbour, the ship entered into the southern Pacific Ocean and its characteristically rough seas.

“We were being tossed up and down by three-metre-high waves,” Hugh says. “That’s not nearly as bad as it can get around here, but it was quite the introduction.”

Fortunately, the waves calmed down during the eight-day voyage to the Antarctic Convergence, the region of ocean where the frigid waters of Antarctica meet warmer waters from the north. The team took samples of the conditions on either side of this boundary, as well as environmental DNA (eDNA), to see what impacts it has on the animals living in the ocean.

The ship’s continuing journey south also meant they crossed another landmark – 60 degrees South. This marks the beginning of the Southern Ocean, and was celebrated by a light-hearted ceremony where the scientists and crew wore costumes, awarded certificates and even kissed a fish!

By now, the temperature had become noticeably colder and icebergs had started to appear as the RV Tangaroa drew ever closer to Antarctica. Eventually, around ten days after leaving port, the first signs of the continent appeared on the horizon.

Initially capped by low cloud, the crew could only catch glimpses of ice and rocks far in the distance. But as the rays of the morning sun dissipated the morning fog, walls of ice and towering volcanoes emerged from the gloom. The crew had arrived in Antarctica.

“The seabed was different everywhere we went,” Hugh remembers. “There was an extraordinary diversity of animals such as sea cucumbers, starfish and sponges, and many areas seemed more or less untouched. The waters this close to Antarctica have largely been left unexploited, so it’s possible that the wider ocean used to look like this before humans started damaging it.”

“In fact, I’m pretty sure some of the sites we visited have never been explored by a research ship before, like the inner channel of Coulman Island. This had 17 species of starfish in just 100 square metres of seabed, which is a crazy level of diversity. It’s more starfish species than can be found in the entirety of the UK’s shallow waters.”

Melting point

While the exploration of new areas is important for understanding and protecting Antarctica’s precious ecosystems, it’s also bittersweet. The reason many sites like these haven’t been explored before is that they’ve historically been locked under the ice, which is now melting at a rapid rate.

While rising temperatures are already damaging for the region’s ecosystems as waters get warmer, there is also a second, less appreciated impact. The sudden influx of freshwater from melting ice can kill animals used to saltwater.

“Rising temperatures are having a serious impact on the Antarctic,” Hugh says. “This year has seen the lowest level of global sea ice on record, meaning we were able to explore a lot more of the Antarctic coast than we expected.”

“It’s not just the ice that’s being affected, either. Some parts of the seabed we visited were completely dead, perhaps from a pulse of heat or meltwater. These areas were a world away from the vibrant diversity we’d seen nearby, with fragments of dead corals, sea urchins and other animals littering the seabed.”

One of the areas most affected by warming is the Ross Sea Ice Shelf, a vast block of ice that covers an area the size of France. It releases large amounts of cold water into the ocean, which flows off the continental shelf in great underwater waterfalls, that spread nutrients and oxygen to the rest of the world.

But parts of the ice sheet, particularly around Ross Island, have recently started to melt much faster. Measurements taken nearby show that warm water is flowing into a cavity under the ice, where it is tripling the melt rate during the summer.

To track how this is affecting the region, the team laid out a series of buoys covered in environmental monitors and released a series of Argo floats as part of an international research programme. These floats automatically sink down into the sea to take measurements before rising back to the surface and broadcasting their data to satellites. After collecting their final data, the team headed back to New Zealand, and into more bad weather.

“We faced 40 knot winds and five-metre-high swells,” Hugh recalls. “We were up and down so much that, if you timed it right, you could jump up a flight of stairs in one go!”

Just under six weeks after they’d left, the RV Tangaroa eventually pulled back into Wellington. But while the cruise might be over, the research has only just begun.

Hugh hopes that he’ll be able to compare Scott and Shackleton’s specimens to the ones collected during the ACTUATE trip to see what impact climate change is having on the echinoderms. He’s particularly interested in seeing how the rising acidity of the Ross Sea is affecting these animals.

“Rising levels of carbon dioxide make the oceans more acidic,” Hugh explains. “This is a particular problem for echinoderms, as it dissolves their hard outer ‘shells’, known as tests, which are made of calcium carbonate.”

“While we haven’t carried out a full analysis yet, the tests of some of the sea urchins we were collecting were troublingly thin. Echinoderms can adapt over time, but the scale of the current changes limit how well they can do this.”

It’s hoped that further research on these specimens will unlock more details about Antarctica’s marine life, from discovering new species to detailing the starfish family tree. Understanding the region’s life is vital to help it, and hopefully stop it from disappearing for good.