Glass sponges multiply after ice shelf collapse

Marine animals called glass sponges have swiftly colonized the seafloor exposed after Antarctic ice shelves disintegrated, researchers report.

In 1995 and 2002, the Larsen A and B ice shelves in Antarctica collapsed and opened up thousands of square kilometers of the seafloor. Scientists took stock of the area’s fauna in 2007 and found invertebrates such as sea squirts flourishing.

Four years later, a research vessel returned to the same spot “after breaking through heavy pack ice in the western Weddell Sea, one of the most inaccessible parts of the Antarctic,” the study authors write. Ice floes threatened to interfere with the remotely-operated vehicle used to scan the seafloor, but the team still “managed to fly it exactly on top” of a previously-surveyed Larsen A site.

The researchers then compared their video footage with the observations gathered in 2007. The density of glass sponges had tripled, and their total mass had doubled, the team reports in Current Biology.

Many of the new arrivals were young sponges of about 50 to 100 square centimeters. The explosion of glass sponges within a mere four years “suggests a much swifter response of the Antarctic benthos to a changing climate than previously assumed,” the authors write. Roberta Kwok | 11 July 2013

Source: Fillinger, L. et al. 2013. Rapid glass sponge expansion after climate-induced Antarctic ice shelf collapse. Current Biology doi: 10.1016/j.cub.2013.05.051.

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