Ice chunks raining on the Antarctic seafloor

	Sculptured iceberg in North Bay, Rothera Point, Adelaide Island, Antarctica. Click here for more information.

The Antarctic seafloor takes a greater hit from sinking ice chunks during years when swaths of sea ice are frozen in place for a relatively brief period of time, U.K. researchers researchers report in the July 17 issue of Science. These results come from a single research site, so more research is necessary, but the scientists say their results suggest that if the Antarctic continues warming, we can expect more sinking ice chunks and, in turn, more physical damage to seafloor habitat. Researchers currently know little about the ecological effects of this so-called "ice scour." It may harm seafloor life, particularly across small areas, but it may also encourage biodiversity by making habitat more varied across larger areas. In this Brevium, Dan Smale and colleagues describe how they set up an underwater network of concrete markers, spaced at regular intervals in three dimensions, at a site off the West Antarctic Peninsula. Each January from 2004 to 2008, scuba divers surveyed the markers to determine how frequently they were being hit by icebergs. The percentage of damaged markers in a given year ranged from 26 percent to 44 percent and corresponded to the duration of "fast ice coverage," the number of days per year when the immediate area was entirely covered with attached sea ice. The authors conclude that ice scouring is likely to intensify and considerably affect seafloor ecosystem in upcoming decades, but that it may actually decrease in upcoming centuries if the glaciers retreat so far that they no longer reach past the coastline.

ARTICLE #10: "Ice Scour Disturbance in Antarctic Waters," by D.A. Smale; K.M. Brown; D.K.A. Barnes; K.P.P. Fraser; A. Clarke at Natural Environment Research Council in Cambridge, UK.