Components of Life

Monday, 19 May, a breathtakingly beautiful morning, a cloudless, cobalt blue sky, endless visibility across leadless ice, riven here and there with pressure ridges, sprawling from horizon to horizon.  Tiny crystals of ice shimmer in the air like an ostentatious theatrical effect, Puck’s magic dust, while hundreds of kittiwakes with delicate, chevron-shaped, black-tipped wings swoop and dive over our rumpled wake.

This ice in gleaming sunlight appears as the vision of some over-caffeinated painter from the Romantic Period, yet it’s empirically real and among the reasons why, helplessly, we fall under the spell of the Arctic.

This ice in gleaming sunlight appears as the vision of some over-caffeinated painter from the Romantic Period, yet it’s empirically real and among the reasons why, helplessly, we fall under the spell of the Arctic. And then, as if more Arctic magic were necessary, we see close aboard a mother bear with two cubs trailing in her tracks ambling off toward the sun….

Well, all right, now with a cooler head, we need to step back to yesterday, auspicious for different reasons than today.  As you may remember from the previous post, the scientists were concerned we had arrived too late, that biological activity—the plankton bloom—had already begun.  As we discovered yesterday, worries were unfounded.  By measuring the water with a device called the CTD, we learned that loads of nutrient-rich “winter water” was still occupying northern half of the Chukchi Sea.  And by using a device called a fluorometer that measures chlorophyll, we learned that zero biological activity was occurring in the water column.  Further, the scientists who went onto the ice for the first time on this trip to measure light penetrating the ice found only a negligible 0.3% penetration.  This is fine news, to everyone’s relief.  So let’s put it into perspective with a brief review of the annual cycle of plankton life in the Chukchi Sea.

Late summer, the phytoplankton and the zooplankton that feed upon them, having consumed the nutrients in the water column, die, sink, and settle into the bottom sediments.  Now it’s the bacteria’s turn to “feed,” and doing so they break down the plankton, producing as a byproduct inorganic nutrients, which remain lodged in the sediment.  As Earth’s axis tilts farther northward, the Chukchi begins to freeze.  The very process of freezing extrudes salt from seawater—the ice we’re seeing today consists almost entirely of freshwater—and deposits beneath the ice a dense, briny soup.  Because that salt-rich water is far heavier than the ambient water, it literally sinks (“convection,” in technical lingo).  Doing so, the dense water displaces the fresher, lighter water below, thus churning the sediment and bringing the nutrients to the surface.  This could not happen so thoroughly over the entire water column if the Chukchi Sea were not so shallow.

   Phytoplankton are plants that, like all their terrestrial relatives, need nutrients to bloom.  But, even while nutrients are present, there will be no bloom (no “primary production”) because the ice has pinched off the sunlight, the other component required by all plants, leaving death-like darkness.  Ice is the thing that distinguishes the Arctic from lower-latitude ecosystems, where time is reckoned in terms of repeating day-night cycles.  But in the Arctic, there is essentially one night (dark, frozen) and one day (light, less frozen) with scant transition between them.  All organisms from phytoplankton to polar bears have evolved in the context of ice.  Few organisms have been able to adapt to the extreme stress of an ice environment, which is why there are relatively far fewer species here than in, say, a tropical rain forest.  And all that have managed to so adapt are said to be “ice obligate.”

But then in spring Earth’s axis tilts back southward, and a new Arctic day begins.  It hasn’t happened quite yet.  The light is here; now, late May, the sun never sets.  The nutrients are here.  The components of life are cocked and ready to explode.  But the ice is still too thick and snow covered, and light has not yet found its way to open water.  Life waits, and so do we to witness the explosion.  The time is nigh, and the “explosion” image is apt.  Opportunity for survival is short, and all Arctic life must hurry.  And so must we if we’re to witness the explosion.

I’m having some trouble concentrating here in the 01-deck lab with such spectacular sights right outside the watertight door to the main deck.  Mid afternoon, the sky remains cloudless; ice still stretches away seemingly forever; the kittiwakes still circle; polar bear tracks crisscross the ice, and every now and again we receive word from the bridge that there’s a bear away on starboard,…on port.  But there’s a problem.  Healy shudders and strains, backs and rams the obdurate ice, more backing than proceeding bow first.  Tom Lowry, the chief engineer, just told me that we’re burning twenty gallons of Diesel a minute to get nowhere (that we burn prodigious quantities of fuel on a climate-change related expedition is an irony lost on no one).  Healy’s armed with four Diesel electric engines capable of 30,000 maximum horsepower.  Two engines are normally sufficient in the ice, but she’s seldom been in ice this early in the year.  Engineering has just brought a third engine online, which Chief Lowery tells me adds not a third more power, but twice the power of two engines.  We’re hearing rumors that the fourth might soon participate.  Healy, too, is ice obligate.

About The Author

Dallas Murphy

Dallas is an author with nine published books, a mix of fiction and nonfiction, most recently "To the Denmark Strait", an account of a 2011 oceanographic expedition with Bob Pickart. The Healy cruise will be his sixth Arctic expedition serving as outreach writer.

3 Responses

  1. Philip Kowalski

    Wow Dallas, that’s an awesome description in many ways. Thank you for sharing it. I,m becoming even a bigger fan of this trip/expedition.
    Phil kowalski

    Reply
  2. Sam Graber-Hahn

    Are the algal blooms caused by algae that have been dormant during the winter or algae that are brought up from the south by water currents?

    Reply
  3. Dallas Murphy

    Hi, Sam,

    The algae is already present beneath the ice. Some of the nutrients are already present, but while the sea is ice covered, no light can reach into the water and so no photosynthesis can take place until the ice melts. When both nutrients and light are present the plankton will bloom quite suddenly. We’ll be here to see it, and we’ll tell you all about what we see. Thanks, Dallas

    Reply

Leave a Reply

Your email address will not be published.