Scientists are literally fishing for clues to global warming s impact on earthly life by drilling holes in the Antarctic ice. In these frigid waters under the ice at the bottom of the world, fish and water-dwelling invertebrates have lived with very little change in their environment for perhaps 11 million years, according to marine biologist Gretchen Hofmann. That is likely to change as global warming raises water temperatures, at the same time that greenhouse gas emissions, especially carbon dioxide, alter the water's acidity, Hofmann said outside her team's mobile laboratory on the sea ice near McMurdo Station, the biggest US science base in Antarctica.

Her research asks the key question: can young fish accustomed to constant cold temperatures and unchanging levels of acidity survive the possible simultaneous change in ocean temperature and acidic balance?

"The news might be good," said Hofmann, who is based at the University of California-Santa Barbara. "Some organisms have a great deal of physiological plasticity and they can say, 'Hey, this is OK, I can survive, I can reproduce, this isn t going to kill me.

"But in some cases, that might not be the case. How will these organisms respond to the changes that are happening right now and to the trajectory of changes of multi-stressors of pH and temperature together? That could be the double whammy for some things."

Chilled life
It makes sense to study these creatures that are accustomed only to the constant chill of the southern ocean, she said, noting that the water where she and others in her lab fish for specimens stays at 29 degrees F (1.86 degrees C), just above the freezing point of sea water.

There is no seasonal temperature variation, and not even any variation between water near the surface and deep down. "If we learn how the most cold-adapted organisms -- the organisms that are most used to cold and no temperature change -- how they respond, we might learn something about the processes in temperate species, figuring out what pathways to look at that might be changing -- or might not be changing," Hofmann said.

Fishing in ice-covered waters, even in the Antarctic spring, means checking giant fishing holes cut in the sea ice, or drilling small ones as needed. Even the big, yard-wide (meter-wide) fishing holes that sit underneath small buildings set on the ice tend to accumulate icy shards that need to be skimmed off before any specimens can be collected.

Drilling new holes about the diameter of dinner plates is a primitive process using a huge drill bit powered by a small engine to punch through several yards (meters) of ice to the water beneath. Another way to inspect under-ice wildlife is to dive down to see it, as a trio of scuba divers did on Saturday. Hofmann's team also used an underwater robot equipped with a camera to investigate under the ice.
(Por Deborah Zabarenko, Planet Ark, 11/12/206)