Polar regions: witnesses to the future
Mission to Antarctica: exploring the polar deep seas
Saturday, 19 March 2004, 12.40 pm. The Polarstern remains caught in a block of ice for several hours. After she broke through the thickening ice, she progresses very slowly in a two metre thick unyielding ice sheet.
The ANDEEP III en WECCON expeditions left Cape Town on 22 January for a three month journey, in order to explore the Antarctic Ocean, the least known sea of our planet, and to survey in detail the water masses and currents in that area. Sampling deep-sea fauna and sediments should make a success of this ‘biodiversity mission’. Trawls, core tubes, fykes and probes were installed in the abyssal zones, where they were subject to an intense pressure. Furthermore, sophisticated sonars (Hydrosweep and Parasound) were used to draw, from miles away, high resolution maps of the ocean floor and its sediment layers.
Within the framework of the federal Belgian Antarctic Programme, in which the RBINS is involved, five Belgian biologists embarked on this international mission. 48 researchers from 13 countries or 4 continents are participating, all with their own specialisation. They have got to work together and need a thorough knowledge about Antarctica to obtain precious results. Here, as well as in the Arctic, deep and cold currents come into being, providing food and oxygen to the other oceans. These currents greatly effect the global climate.
Present climate changes are experienced more intensely in the polar regions than anywhere else. It is urgent to gather the best possible knowledge about the current state of biodiversity in this relatively well-preserved environment. How will warming and the increase in UV-B radiation effect biodiversity? Will they eliminate species in Antarctica, and allow others to invade the region? And how may these biodiversity changes, in their turn, influence the polar and neighbouring ecosystems? How can the knowledge acquired in Antarctica be applied to the rest of the world?
An irrefutable answer to these questions requires a lot of data, and our mission should contribute to this.
Claude De Broyer and Bruno Danis
(from the Weddell sea, Antarctica)
4935 metres... a depth record for the RBINS team. Deep-sea carnivores are caught in fykes, since otherwise, these good swimmers usually manage to escape. The ‘cage’, a cubic metal structure to which the fykes are fitted, is equipped with an acoustic release system. This system is essential to the success of the operation, because, at our signal, it unlashes the cage from the ballast holding it on the ocean floor. After a few attempts, we receive the confirmation signal: ‘Posidonia’ enables us to follow the fykes rising slowly to the surface. By means of acoustic communication, this special beacon, fitted to the cage, informs us of its position (longitude, latitude, depth) in real time. This way, we can retrieve the cage, as long as the sea is not too covered with ice!
4935 metres… These depths are often thought as being infinite lifeless abyssal plains. However, our fykes are bulging with hundreds of crustaceans, mainly amphipods. Some of these are unknown to us, and show morphological characteristics never seen before, allowing us to retrace their evolution. With sizes up to 12 cm, some are quite gigantic, compared to their relatives from the temperate seas. They grow that big, because of the high oxygen concentration in their environment. Some living individuals are kept in aquariums in chilled containers, permitting conditions that resemble their original habitat as closely as possible. These animals are going to be submitted to several tests, that will impart us a profound knowledge about the foundations of life in the extreme circumstances deep in the polar sea.