You are currently browsing the tag archive for the ‘shelf’ tag.

The WISSARD borehole operation on the Ross Ice Shelf

The WISSARD borehole operation on the Ross Ice Shelf

Outside my window, New York City is experiencing a blizzard. The city is on high alert: the mayor is issuing all sorts of proclamations while, at the grocery store, a horde was stripping the shelves bare. Meteorologists and weather scryers warn that the city could be in for up to 36 inches of snow!

x-graphic

Being forced to live under 3 feet of snow is an alarming prospect to me, but it is nothing for the life forms which were just discovered by a team of scientists exploring the extreme ecosystems of Antarctica. The Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project has just drilled through the Ross Ice Shelf—a gigantic sheet of ancient ice which covers an area approximately the size of France. The amazing (albeit stupidly named) WISSARD team drilled through 740 meters (2,430 feet) of shelf ice by means of a specialized hot water drill in order to lower a cylindrical robot submarine into this hidden sea. The insertion point for the probe was near where the ice sheet, the ocean, and the long-buried lands of Antarctica all meet–nearly 850 kilometers (530 miles) from the open ocean. At the converging point of ice, rock, and water, there are vast “grounding lines” of ice which attach the glaciers to the floating Ross sheet. Below the ice, a constant rain of rocks ranging in size from microscopic dust to house size boulders fall upon the sea floor. The temperature of the sea water is 28 degrees Fahrenheit (minus 2 degrees Celsius).

An ice fish and the robot submarine looking at each other

An ice fish and the robot submarine looking at each other

The scientists had speculated that fresh melt water from inland would create an estuarial environment beneath the ice. They found no evidence of that, but they did find all sorts of strange lifeforms. The barrage of rocks keep any sessile lifeforms from finding a home in these waters, but hardy motile sea creatures live there including fish, jellyfish, and amphipods (hardy crustaceans which thrive in extreme environments). The newly discovered Ross fish (which yet lack a name) are the southernmost known fish of the world. They are translucent and pink and measure about 20 centimeters (8 inches) long. As with the crazy underground catfish of South America (which live below the water table), the existence of these ice fish raises an immediate question: what do they live on? The sun shines little through half a mile of solid ice, so what do microorganisms as the base of the food chain use for energy? These organisms do not rely on “cold seeps” (which we explored in a previous post), but the answer is not entirely unrelated.  Scientists speculate that the geological upheaval releases nutrients in the form of carbon. It seems that an ancient fossilized ecosystem eroding away into the ocean. The strange fish and sundry invertebrates of the Ross Ice shelf may ultimately be reliant on fossil fuels—which makes them our spiritual brothers for, in this era of cheap frack-gas humankind is more tied to fossil fuels than ever [looks at snow outside and turns up heat].

A fish seen at the Ross Ice Shelf grounding (Deep-SCINI UNL, WISSARD)

A fish seen at the Ross Ice Shelf grounding (Deep-SCINI UNL, WISSARD)

Life around a Cold Seep

This week Ferrebeekeeper has been concentrating on the theme of discovering new life—a search which is very much ongoing even in today’s used-up overpopulated Anthropocene world.  This concept has taken us to the mid levels of the ocean and the mountain jungles of Thailand and Vietnam to encounter species unknown (like this mystery sea slug, the tiny parasitoid wasp, and even a large hoofed mammal). However what is even more shocking is that our world features entire ecosystems rich with life that have only just been discovered.

A photograph of a pool of brine on the bottom of the ocean

A cold seep is an ecosystem on the bottom of the ocean formed around hydrocarbon-rich fluids which seep out of the earth and either “bubble up” or pool at the bottom of the ocean.  The geography of such areas is alien to our perceptions: black pools of asphalt, barite chimneys, and undersea lakes of dense brine (which traps hydrocarbons and sulfites) are surrounded by otherworldly “reefs” of tube worms and benthic mollusks.  The tube worms symbiotically partner with bacteria capable of “feeding” off the hydrocarbons while the mollusks filter feed on the archaeobacteria.   Whole communities of grazers, scavengers, and predators then form around this base.  Such communities are remarkable because they do not rely on photosynthesis as a source of energy and nutrients (much like more famous “black-smoker” ecosystems which are also chemotrophic ecosystems—but which form around hot volcanic vents).  Cold seeps themselves were only discovered in 1983! Now that oceanographers know what to look for, cold seeps are being discovered in locations where we would never have looked for large complicated webs of life.

A Map of the collapsing Larsen Ice Sheet

In 2005, an oceanographic research team studying the seas once covered by the Larsen ice shelf (a melting shelf of ice located off the eastern side of the Antarctic Peninsula) discovered a cold seep community thriving in a glacial trough 850 meters (2,800 feet) beneath the ocean’s surface.  The scientists found great mats of bacteria living on methane.  These bacterial mats were in turn grazed on by strange bivalve mollusks and brittle sea stars.  To quote EOS (a journal of the American Geophysics Union):

These results have implications for the discovery of life in extreme environments, including those found beneath the enormous extent of existing ice shelves and large lakes that lie beneath the Antarctic Ice Sheet. Because of its restricted conditions, the seafloor beneath ice shelves may provide a suitable, widespread habitat for chemotrophic systems; given this, there may be many more such habitats waiting to be discovered beneath existing ice shelves….The seafloor beneath Antarctica’s floatingice shelves covers more than 1.54 million square km [Drewry, 1983], an area of the same order of magnitude as the Amazon basin of Brazil or the Sahara desert.

So science is only just beginning to apprehend the sorts of biomes which are found across huge swaths of Earth.  There are even more remote areas which are wholly unknown—like Lake Vostok, a subglacial lake wholly isolated from the rest of Earth (including the atmosphere) for 15 to 25 million years.  As continental drift and the Antarctic Circumpolar Current froze Antarctica, Lake Vostok was trapped beneath 4,000 m (13,100 ft) of ice, and it has remained so until this year (when an intriguing but sloppy Russian drilling expedition means to pierce the lake).   What scientists discover beneath the other ice dwindling shelves, and what the Russians find beneath the East Antarctic Ice Sheet will have broader implications for how we conceive of life on Earth–and beyond.

A watercolor painting by of chemotrophic life by Karen Jacobsen, an artist who has traveled to the bottom of the ocean via bathysphere to record her impressions!

Ye Olde Ferrebeekeeper Archives

September 2020
M T W T F S S
 123456
78910111213
14151617181920
21222324252627
282930