Tuesday, January 30, 2018

Ice edge

I heard the reaction before I heard the blast.
The sea ice edge (and a helicopter blade)

"Whoa!" exclaimed Chelsea, leaning back in her thick blue coat and raising her camera to her eye. Then I heard the rush of air as the whale breathed behind me and turned around to catch its dorsal fin disappearing below the sea surface. The large gray minke whale was about 10 m away from me.

I was standing on a shelf of sea ice. Below me was the Ross Sea, stretching 600 m to the seafloor beneath my feet. Behind me, the white, snow-covered ice shelf ended abruptly and gave way to the deep blue of the ocean. We were at the ice edge collecting samples.

Mt. Erebus and the sea ice edge
The sea ice edge is a very interesting place biologically. The ice acts like a blanket on the ocean, dampening waves and maintaining a stable water column. Phytoplankton bask in the sunlight in the stable water and grow like mad, providing a key energy source for krill and pteropods. The abundant food sources attract whales and fish that gorge on these tiny creatures. Penguins swim in the sea, chowing on fish. Orcas hang around hunting penguins. It's one massive party of a food web.

Adelie penguins and the Transantarctic Mountains 
And it is absolutely stunning. I wish I could have just stood in the middle of the ice and spun around like Julie Andrews in The Sound of Music. My view was flanked by Mt. Erebus on one side and the Transantarctic Mountains on the other. The vast white carpet of sea ice reached back toward land, and in the other direction was the endless deep blue of the Southern Ocean.

We drilled a series of holes in the sea ice to lower instruments through and then approached the edge itself. As a safety precaution, two mountaineers assisted us by drilling ice screws into the ice and attaching belay ropes. Each of us wore a climbing harness and was clipped into the belays so we couldn't fall over the edge. We deployed plankton nets and a CTD (conductivity-temperature-depth gauge), trying all the while not to be distracted by the beauty around us. At one point, as we were pulling up the CTD, a group of Adelie penguins jumped into the water from a nearby icy outcrop and began porpoising, jumping out of the water like dolphins. I held the CTD line firmly in one hand, lifted my head, and stared in awe at the quirky, tuxedoed creatures swimming with perfect grace.

As I climbed back into the helicopter, I could not help but take one last look around me. The ice edge really is a magical place.

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