Listen live on the Internet to what’s going on under the Antarctic sea-ice. The Alfred Wegener Institute’s PALAOA underwater acoustic observatory has made this possible for over five years.
The acoustic observatory has been continuously recording sounds under the ice near Neumayer Station since 28 December 2005. It provides the world’s longest time series of civilian acoustic measurements, enabling researchers to study the presence and behaviour of animals under the Antarctic ice. This has led to many new findings on the distribution and behaviour of several whale and seal species.
Recording the underwater calls of marine mammals is one of the most promising methods to study distribution and seasonal migration of these animals in the ice-covered Antarctic. Visual sightings of marine mammals in Antarctic waters are rare since human access is limited and animals only occasionally surface to breathe. Acoustic recordings, on the other hand, can be made year round. By means of the PALAOA observatory, ocean acoustics experts from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association have discovered that leopard and Ross seals populate Antarctic waters near Neumayer Station III.
For many sounds it is now known by what species they are produced and, in some cases, in what type of behavioural context they are produced. Such acoustic data can be used to derive information on the timing of mating and reproduction of the various species. Acoustic behaviour of leopard and Ross seals, for instance, shows that both species also reproduce in coastal Antarctic waters. Previously this was only known for Weddell and crabeater seals.
Inter-annual comparisons of acoustic data indicate that the timing of reproduction is linked to the availability of certain types of ice on which the animals give birth to their young. “Some seal species actually are acoustically present in the PALAOA recordings in the same calendar week every year,” Dr. Ilse van Opzeeland describes the surprisingly exact timing of the animals. Researchers at the Alfred Wegener Institute were astonished to hear humpback whales on the edge of the Antarctic continent, even in austral winter. The observatory has also recorded calls of Antarctic blue whales, thereby refuting the existing presumption that the largest animals living on Earth avoid ice-covered waters.
Even 50 years after the end of commercial whaling in Antarctica very little is known about the long-term population development of these nearly exterminated giant whales. Traditional counts based on sightings often record only a few of these marine mammals during an expedition over several months. The PALAOA data, on the other hand, contain blue whale vocalisation almost every day because the calls of these animals have a very great range extending to several hundred kilometres. Such information is extremely important to gain a general understanding of the behaviour, size and recovery of the stocks of large whales, which are still endangered in a variety of ways.
The loudest sounds recorded by PALAOA stem from iceberg collisions. About once a year giants the size of Berlin bump into each other or into the edge of the ice shelf. These create quite a racket in the Bremerhaven offices of the ocean acoustics specialists, whose daily work is accompanied by the live sounds from the Antarctic. Aside from their usefulness for research, the extraordinary sounds from the Antarctic Ocean have also found their way into radio and television as well as into the works of musicians, composers and creative artists. In 2010 more than three million visitors saw and heard the walk-on sculpture and sound installation “Iceberg PALAOA” floating on the Ruhr River in Essen – it represented one of the highlights of the European Capital of Culture “RUHR2010”.Background:
The recordings are transmitted via a WLAN and satellite link directly to Bremerhaven and can be heard as a livestream here: http://www.awi.de/PALAOA
The Alfred Wegener Institute conducts research in the Arctic, Antarctic and oceans of the high and mid latitudes. It coordinates polar research in Germany and provides major infrastructure to the international scientific community, such as the research icebreaker Polarstern and stations in the Arctic and Antarctica. The Alfred Wegener Institute is one of the sixteen research centres of the Helmholtz Association, the largest scientific organisation in Germany.
Margarete Pauls | idw
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