Molgula pedunculata, a pioneer in climate change
The sea squirt Molgula pendunculata is characterized by its explosive population growth
Photo: Julian Gutt
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This semi-transparent animal belongs to the group of sea squirts. It is a sedentary species living on the Antarctic seabed in water depths between 30 to 300 m. Molgula pedunculata feeds on microalgae that grow in the sunlit upper layers of the ocean, and later sink down to the bottom of the sea. The sea squirt attains maturity after three to five years and a size of about 25 cm, representing a growth rate much faster than that of most benthic inhabitants of the Antarctic Ocean. The photo was taken using a remote-controlled underwater vehicle (ROV) on the east coast of the Antarctic Peninsula.
Deep-sea animals, such as starfish, characterize life under the ice shelf.
Photo: Julian Gutt
The importance of Molgua pedunculata in the Antarctic ecosystem
Climate change in the Antarctic has in recent decades caused the breaking off of gigantic floating ice shelves from the coast. The largest of these, about 40 times as large as the state of Bremen, was the Larsen A/B ice shelf located on the east coast of the Antarctic Peninsula. Ecologists at the AWI are interested in finding out what life looked like in an ecosystem previously shielded by an "Ice lid". Food for the ice-covered fauna could only have drifted laterally under the shelf over large distances, and in small quantities. One surprise, was the discovery of some animals, usually considered deep-sea species, that were found here in water just 200m deep (see photo right). Even more exciting is the question of how the ecosystem will change after the disappearance of the "ice lid”. Molgula pendunculata is one of the pioneers of the seabed, which was able to settle very quickly and en masse after the ice shelf broke off. Other, much slower-growing species, have not yet responded, even after several years. However, the wildlife of the open ocean, e.g. krill, fish, seals and whales, have already discovered this new habitat for themselves. It will be exciting to watch, in the coming years, if other bottom dwellers will get a foothold in this area, thus regionally enriching the species diversity. On the other hand, the survival of rare deep-sea animals adapted to the shallow, formerly ice-covered conditions, is highly endangered.