Friday, November 26, 2010

The Ob Tube

Below the Ice

At temperatures below freezing, the water below the ice is crystal clear.  The sun shines through the ice above emanating colors of blue, green, yellow, and orange, accenting the deep blue of the watery world below.  A large jellyfish slowly pulses its path through the water.  The edge of Ross Island can be seen, dropping down to the depths; scattered along its underwater slope crawl bright red starfish and sea spiders.  White, flat, and shoe-lace-like, large worms creep along the sediment.  Shrimp-like critters (amphipod? decapod? copepod? I'm not a marine biologist!) swim placidly through the water column and along the underside of the ice.  Tiny, silver, antigregarious (I make words up sometimes) fish are spaced throughout the water column, moving would too if you were so cold!  *Interesting side note:  Antarctic fish have anti-freeze proteins they use to keep the water inside their cells and blood from freezing, since the temperature of the water is below the freezing point of their blood.

As terrestrial creatures studying Weddell seals, we are only able to observe the seals while they are on top of the ice or blowing bubbles in the holes in the ice.  But they're real home is the water, which is why all the pups are learning to swim.  They will spend most of their lives in the water after mommy leaves them.  One could put cameras under the ice at tide cracks or send a well-insulated diver down to watch and record the seals, or one could use an "Ob Tube" (or Observation Tube).  The Ob Tube is a vertical tube placed through the ice and into the water, just large enough for a man to crawl down to the bottom, where a very small space encircled with windows gives a 360 degree view of the world below the ice.  It is an enchanting experience for us who are always trying NOT to go below the ice (by falling in a crack or otherwise), but are always wondering..."what is it like down there?"

Hmmm...deep dark tunnel of delight
Looking back up the tube

Inside the Ob Tube--Glenn scanning for seals
Thierry hunting for penguins or seals out the windows

Tiny fish in the deep blue

Unfortunately, we are not permitted to have our own Ob Tube, but a visit to one right outside of McMurdo suffices for us, especially when we are treated to a real, underwater swimming seal (that is tagged!).  Sorry the video quality is so dark and poor, you might have to turn off all the lights and watch it at night to see anything:


Friday, November 19, 2010

Learning to Swim

Part of the process:

Video and editing thanks to Jessica Farrer, Weddell seal technician

Thursday, November 18, 2010

Pura Antarctica

The Antarctic summer has begun: the sun makes a complete circuit above our head every day, never dipping below the horizon.  The light effects on the edge of the photo are called sundogs, formed from ice crystals in the air.
The summer sun, in its seemingly-perpetual circling of the southern-most continent, like a halo being drawn and redrawn across the margins of the sky, has begun its deconstruction of the frozen seas.  The sea-ice edge creeps closer into Erebus Bay, the once frozen and hard layer of ice being stripped clean off the surface, revealing the depths of ocean below.  The northern-most edges of Ross Island, not long ago like a mountain rising from a plain, now lay bare to the wind-tossed sea.  The melting ice must bring joy to the Adelie penguin's heart, for no longer does this short, excitedly gesturing penguin have to traverse miles on the ice upon its short legs to find its colony at Cape Royds.  Now, the hurried penguin can take a relatively short waddle-jaunt to claim its prime nesting spot in the colony.

Adelie penguins chillaxin' on the sea-ice edge.  Royal Society Range in the background.

Adelie penguins on nesting site at Cape Royds.

These are the early arrivals, getting the primo nesting spots.  There was endless squabbling over pebbles and stones as one penguin would steal a stone from someone else's nest to build up its nest.  Lots of emphatic displays, gesturing, and guffawing.

Further inland (or "inice," as the case is here), vast stretches of flat frozen ocean still lay firm and strong.  As the summer slowly sneaks forward, the tidal cracks along the edges of the islands like Big Razorback and Tent Island, and along the coast of Ross Island at Turks Head and Hutton Cliffs, begin to widen.  Mush pools form, areas of...well...mush.  The melting ice gathers in depressions creating these pools of thick porridge of ice and water, much like the consistency of a tropical fruit smoothie.  And in these mush pools and tidal cracks, the Weddell seal pups are learning to swim.

Mom and pup in slush pool...they often just lay there for hours.

To be continued...