Antarctic deep sea teems with life

Researchers systematically describe the huge biodiversity in the Antarctic deep sea

Antarctic © NOAA
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In the inhospitable, icy and dark deep sea near the South Pole, little or no life had been suspected - until researchers discovered a surprising biodiversity there in recent years. Now for the first time the evolutionary history and the distribution pattern of many organisms could be described. The researchers report this in "Science".

"It is noteworthy that many shallow-water species are found in deep Antarctic waters, but also many typical deep-water genera are found in the Antarctic shallow water, " explains Michael Raupach from the University of Bochum. "The reason for this is probably the low water temperature of both the deep sea and the surface water, which allows temperature-sensitive animals a corresponding spread in both depths, " said the biologist of the Department of Evolutionary Ecology and Biodiversity. This also applies to woodlice such as Asellota, which offer due to their species and individuals wealth for molecular genetic studies of distribution, evolutionary history, population structure and speciation.

Samples from 6, 000 meters depth

The three-month ANDEEP (Antarctic benthic deep-sea biodiversity) expedition, organized by Angelika Brandt and Brigitte Ebbe, was launched in 2002 and 2005 and is part of the international Census of Diversity of Abyssal Marine Life initiative "CeDAMar" international team of biologists for the first time on a systematic recording of the Antarctic deep-sea fauna. The researchers took samples from the Antarctic seabed up to a depth of 6000 meters from the German research icebreaker "Polarstern" under the coordination of the Alfred Wegener Institute for Polar and Marine Research (AWI). A variety of fishing gear such as box grabs, Epibenthosschlitten or multi-core drills were used. One focus of sampling was the deep-sea level of Weddell Lake.

Number of species has been underestimated so far

"In addition to the discovery of a variety of previously unknown species and important new insights into the biogeography of various organisms, we were able to catch Asellota the deep sea for molecular genetic studies for the first time during these expeditions, " says Raupach. Researchers looked at mitochondrial and nuclear genes to draw conclusions about evolutionary history and population structure. The large variety of forms of Asellota, especially within the deep sea families, so far made hardly reliable relational hypotheses possible. The results show that the settlement of the deep sea took place in several groups independently and probably at different times from each other.

"Noteworthy is a morphologically hyperdiverse grouping in which the Mesosignidae, Macrostylidae, Janirellidae, Ischnomesidae, Desmosomatidae, Nannoniscidae and Munnopsidae summarize, " explains Raupach. Further molecular results confirm a high genetic variability within morphologically similar species and the existence of so-called cryptic species: Species that, while morphologically indistinguishable, are genetically distinct. "This is crucial for deep-sea biodiversity research as it shows that the species numbers of Asellota and other groups have been underestimated so far, " said Raupach. display

(idw - Ruhr-University Bochum, 21.05.2007 - AHE)