First cold water coral ecosystem discovered off coast of Mauritania

The 190km long coral wall is up to 60 metres high

November 2010: A cold water coral ecosystem has been found off the coast of Mauritania in Africa for the first time. A research team led by Professor Andre Freiwald of Germany's Senckenberg Institute came across the reef, which was full of living animals during a research trip. The scientists also stumbled across the giant deep sea oyster, a Methuselah among sea creatures.

The coral wall on the continental shelf off the coast of Mauritania is between 50 and 60 metres high and 190 km long. When the Swedish robot pilot Tomas Lundälv of the Sven Lovén Centre of the University of Gothenburg set down a diving robot on the seafloor at a depth of 615 metres, the scientists on board the research ship found themselves transported via video link to the middle of a flourishing coral ecosystem.


André Freiwald reports on a heavily calcified Lophelia coral with orange-red polyps and gorgonias, which, beside the reef-building stony corals, formed imposing octocoral gardens in the dark and otherwise inaccessible habitat. According to the excited expedition report, giant clams also hang on the coral galleries, in exactly the same way as is found elsewhere in Norwegian reef systems.


Traditionally associated with Scandanavia and the irish Sea
Such impressive ecosystems were previously associated with areas much further to the north, around Scandinavia and in the Irish Sea. Unlike their tropical relatives, found by snorkellers and scuba divers in the illuminated and significantly warmer surface waters, cold water corals live at a cold 13 degrees centigrade in the dark and nutrient-rich deep sea region below 200 metres. Prof Freiwald was aware of a loose cold water coral reef which extends to southern regions but until now scientists had found only fossil coral reef structures on the seafloor off the coast of Gibraltar and Morocco.

While the Maria S. Merian, equipped with a dynamic positioning system, accompanied the diving robot step by step, the on-board coral team followed the exploratory dive, about 60 km west of Cape Tamirist, which took them into uncharted waters. Metre by metre, the device worked its way up the slope following a navigation chart drawn up by the Senckenberg scientist, Dr Lydia Beuck, when at a depth of approximately 500 metres, the coral team discovered further Lophelia. At the same time, the diversity of sponges and large crustaceans at the location increased significantly.

Giant deep sea oyster that can live for more than 500 years
Among other things, the scientists found the powerful carrier crab Paromola here, and on diving through the rocky landscape, also discovered the giant deep sea oyster Neopycnodonte, also never before observed so far to the south. These oysters form thick populations and can be described as Methuselahs among animals, with some individuals living for more than 500 years.


For the scientists on board the Maria S. Merian, the discovery of the ecosystem with living cold water corals came as a surprise. Prof Freiwald thinks one explanation may be that offshore winds push the surface waters from the Mauritanian cliffs out into the open ocean, allowing a flow of cold and nutrient-rich water from the depths.

The 16th research voyage with the Maria S. Merian, under the leadership of Professor Hildegard Westphal from the Leibniz Centre for Tropical Marine Ecology in Bremen, ends later this month in Cape Verde. Until then, it will stop at and chart further parts of the coral system in the canyon of the continental shelf off the coast of Mauritania. Prof Freiwald expects the next dives on this expedition to provide information as to whether the newly discovered ecosystem represents a single structure or whether a spatially extended living reef province exists in the southern waters.

http://www.wildlifeextra.com/go/news/coral-deepwater001.html