Antarctica's majestic underwater world is trying to adapt to a warmer planet

Researchers want to know what will happen to the surrounding ocean salt water if the glaciers melt, particularly what happens to the ecosystems that live in it -- or under it.  Credit: Lars Boehme

(CNN)Icebergs surrounded a team of researchers in January as they cruised toward Antarctica. The team had been studying a thriving underwater ecosystem near the continent for years, but thanks to new modeling and powerful instrumentation they were able to navigate through a crumbling landscape of ice to their destination.

"We saw a lot of icebergs and they were impressive -- the size of buildings," Patricia Yager, a professor at the Department of Marine Sciences at the University of Georgia, told CNN. "Some are as tall as the Statue of Liberty, up to 300 feet above the waterline."
"There's a lot of melting going on," Yager said. "Lots more than I expected. There was more meltwater and more heat in that ocean than I imagined."
    Large Antarctic iceberg with wavy contoured surface.   Credit: Lars Boehme
    The Thwaites Glacier in Antarctica, roughly the size of Florida, is melting at a rapid rate. In fact, most of the ice in western Antarctica is melting. But the Thwaites Glacier -- also known as Doomsday Glacier -- is one of the most unstable in Antarctica. This is very worrisome because of the sea level rise it could cause.
      But it's more than that.
        "What we realized as biologists and chemists and ecosystems scientists was, our ecosystem was also being impacted," Yager said.
        Scientists believe this ecosystem is pivotal to climate research, and years of extraordinary warming has allowed them to finally see it with their own eyes. Everything in this ecosystem -- from the small phytoplankton to the larger seals and penguins -- is being impacted.
          Yager and her fellow researchers want to know what will happen to the surrounding ocean salt water if the glaciers melt, particularly what happens to the ecosystems that live in it -- or under it.
          Nathaniel B. Palmer ship among icebergs.  Credit:  Dr. Patricia Yager

          The entire food chain is being impacted

          While Yager and her team were in Antarctica, they found an elephant seal in the polynya -- an oasis of open water where sea ice would normally exist -- that they were studying.
          "Nobody's reported seeing an elephant seal there before," she said. "What we see is if there's a shift in the ecosystem, the animals respond. The problem is they're not just responding to the food. They're also responding to change in habitat and ocean currents."
          But how did that elephant seal get there? Well, that is where these important microorganisms called phytoplankton come in.
          A seal resting on a piece of sea ice with the Nathaniel B. Palmer ship in the background.  Credit: Ms. Li Ling PhD student at KTH Royal Institute of Technology
          Phytoplankton are vital to the Antarctic food chain. Krill eat the phytoplankton, and animals like seals, fish, and penguins eat the krill.
          Certain coastal regions of Antarctica have the highest abundances of phytoplankton in the world.
          "The Amundsen Sea Polynya is about half the size of the state of Georgia," Yager said. "So it's a big feature. On a per meter squared basis, it is more productive [than other polynyas] for reasons we think that are related to this melting glacier."
          It was discovered about a decade ago that this meltwater was providing iron-rich water to the polynya. So much iron that it was providing beneficial fertilizer to the local ecosystem.
          However, high amounts of iron are not usually found in the coastal Antarctic because there is so little exposed rock there.
          "The Southern Ocean is famously known for being a high-nutrient, low-chlorophyll zone," Yager said. "We figured out that this ocean, for the most part, has plenty of nitrogen but it is missing another important fertilizer, which is iron."
          Where there's iron, there are phytoplankton blooms.
          A branched sessile invertebrate, seen through a dissecting microscope, was found in a sediment core. The branched structure is approximately 1 cm in size. Credit: Dr. Lisa C. Herbert, Postdoctoral Fellow at Rutgers University
          This ecosystem may have adapted to climate change in some ways, but it will need to change in many more ways to survive rising temperatures.
          "We knew from the satellites that there was a big phytoplankton bloom in this area. It's why we went to first explore this region back in 2007. Rob Sherrell, a trace metal geochemist from Rutgers University, pointed out that if there are algae blooming, then there must be iron. The question was, where was the iron coming from?"
          What the researchers didn't understand was why meltwater was coming out from where it was, and why it was so rich in iron, Yager said.
          "So we went down there thinking, okay, well, the glacier has iron in it, and the melting glacier is dribbling iron into the ocean, which is a perfectly reasonable hypothesis. That's what's happening in parts of Greenland," Yager said. "However, turns out, that's not what's happening. It's more interesting than that."
          Back home, the science team set out to build a computer model to explore how the iron delivery worked.
          "That's what we went down to test this year," Yager said. "The model suggested that the iron is actually coming mostly from the deep ocean water responsible for melting the glacier, but the delivery of iron to the surface is because of the added buoyancy from the melt."
          That upwelling of iron is fueling thriving ecosystem communities with species of algae, icefish, seals and jellyfish.
          A small Antarctic jellyfish.   Credit: Daisy Pickup, PhD Student at University of East Anglia
          It may seem hard to believe that organisms could thrive in such cold environments, but there is life down there. And when you change that environment, it can have dire consequences.
          "That life loves being down there," Yager said. "If you take them away from that cold environment, they don't survive. If you take the bacteria or the organisms that live down there and you put them in warm water, they often die."
          So while on the surface it may seem like a good thing that parts of these ecosystems are thriving -- such as the phytoplankton, zooplankton -- other aspects of the ecosystem can't adapt as easily.
          "For example, the Adelie penguins really depend on sea ice, and as the sea ice has disappeared from the peninsula in western Antarctica, the Adelies have declined dramatically because their habitat is gone," Yager said. "What we're seeing is an ecosystem shift. Adelie penguins are moving to new areas where there is more sea ice, and other penguins that don't need the sea ice are moving in."
          Colony of penguins near Bear Peninsula in Antarctica.   Credit: Ms. Li Ling PhD student at KTH Royal Institute of Technology
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