As ice melts, life abounds in Antarctic

Fish in a glass sponge
Marine life is flourishing on the seabed in waters once covered by giant ice shelf in Antarctica that collapsed due to global warming. In this image, a fish (Trematomus sp.) is hiding in a glass sponge.

The collapse of a giant ice shelf in Antarctica has proven a bounty for the sea creatures eking out an existence in the once-dark waters, according to new research that highlights just how quickly some marine life can adapt to a warming world.

The Larsen A ice shelf broke up and collapsed in 1995, exposing the permanently dark seafloor to the fruits of sunlight, which fuels the growth of plankton and sea-ice algae at the surface. The plankton and algae drift to the seafloor when they die.

"This unprecedented source of food appears to be triggering important changes in the seabed biota," Claudio Richter, a marine scientist with the Alfred Wegner Institute in Germany, told NBC News in an email.

Richter used a remotely-operated underwater vehicle to video-survey a region of the seabed in 2007 and 2011. He found the density of glass sponges – vase-like creatures that can grow more than 6 feet tall – increased threefold between the voyages.

The finding, published today in the journal Current Biology, came as a surprise given that researchers thought the glass sponges would grow slowly in the frigid waters with a patchy, seasonal food supply.

"In spite of these limitations, the changes came about very fast," Richter said. "The surprise is not so much the change itself, but rather the magnitude of change – which is orders of magnitude higher than previously thought."

Image of glass sponges
This is a typical glass sponge community in the Eastern Weddell sea (in an area not covered by ice shelves).

During the 2007 survey, the study area was dominated by sea squirts. Four years later, the squirts are all but gone, replaced by a young forest of glass sponges, which is changing the entire seafloor community, he noted.

"Without the sponges, the seafloor is flat. With sponges, it is 3-dimensional," he explained. "Sponges open up a third dimension and thus many new opportunities for many new species. This is why sponges, like corals in other areas, are so important."

To date, sponges are reaping the benefits of warming in Antarctica, though whether they are climate change winners in the long term is unknown. For example, snails and starfish, which feed on glass sponges, were largely absent from the survey area in 2011. That may not be the case for long.

"However, if ice-shelf collapse extends to the East Antarctic, as some models suggest for the future," Richter said, "the newly exposed seabed areas are likely to be colonized by glass sponges."

John Roach is a contributing writer for NBC News. To learn more about him, visit his website.