Polarstern examines re-colonization of the seafloor in Antarctica

Simulation of iceberg scraping: the first field experiment to test re-colonization of the seafloor in Antarctica

The 'Polarstern', research vessel of the Alfred-Wegener-Institute for Polar and Marine Research, has just started a long-term field experiment on Antarctica's seafloor. Scientists are investigating how bare patches of the ocean's floor are re-colonized after disturbance events such as scraping icebergs.

In 300m water depth, the sea floor was cleared of all macro-organisms using a drag net. This simulates the effects of scraping icebergs on the benthic fauna. The experiment is supported by the 'Bund fuer Naturschutz' and has been licensed by the 'Bundesumweltamt' (the German Ministry of the Environment).
Thousands of drifting icebergs around Antarctica repeatedly come in contact with the ocean floor and create bare areas open for new colonization and succession by organisms. Generally, scientists studying this type of natural disturbance do not know when it was initiated. In contrast, 'time zero' of this experiment is controlled, making this study, which is carried out by AWI ecologists in collaboration with their international partners, a novelty in Antarctic waters.

The denuded patches will be gradually colonized by various animal species, including sponges, bryozoans, ascidians and cnidarians. This process will be monitored over the following years using both visual and invasive sampling methodology. Of interest are not only the succession of species and composition of colonisers, but also the time it takes for a diverse and structurally complex species community to re-develop on the seafloor. The recovery characteristics of the benthic faunal community will allow conclusions to be drawn about the stress tolerance of Antarctic ecosystems and, consequently, the necessity for its protection. Apart from this, scientists will gain insight into the functioning of a marine ecosystem which has been largely free of human impacts.

Bremerhaven, 6.1.04