Publication Date:
2023-06-27
Description:
In 1948, Le Danois reported for the first time the occurrence of living cold-water coral reefs, the so-called "massifs coralliens", along the European Atlantic continental margin. In 2008, a cruise with R/V Belgica was set out to re-investigate these cold-water corals in the Penmarc'h and Guilvinec Canyons along the Gascogne margin of the Bay of Biscay. During this cruise, an area of 560 km**2 was studied using multibeam swath bathymetry, CTD casts, ROV observations and USBL-guided boxcoring.
Based on the multibeam data and the ROV video imagery, two different cold-water coral reef settings were distinguished. In water depths ranging from 260 to 350 m, mini mounds up to 5 m high, covered by dead cold-water coral rubble, were observed. In between these mounds, soft sediment with a patchy distribution of gravel was recognised. The second setting (350-950 m) features hard substrates with cracks, spurs, cliffs and overhangs. In water depths of 700 to 950 m, both living and dead cold-water corals occur. Occasionally, they form dense coral patches with a diameter of about 10-60 m, characterised by mostly stacked dead coral rubble and a few living specimens. U/Th datings indicate a shift in cold-water coral growth after the Late Glacial Maximum (about 11.5 ka BP) from shallow to deep-water settings.
The living cold-water corals from the deeper area occur in a water density (sigma-theta) of 27.35-27.55 kg/m**3, suggested to be a prerequisite for the growth and distribution of cold-water coral reefs along the northern Atlantic margin. In contrast, the dead cold-water coral fragments in the shallow area occur in a density range of 27.15-27.20 kg/m**3 which is slightly outside the density range where living cold-water corals normally occur. The presented data suggest that this prerequisite is also valid for coral growth in the deeper canyons (〉 350 m) in the Bay of Biscay.
Keywords:
B08-01; B08-02; B08-03; B08-04; B08-05; B08-10; B08-11; B08-12; B08-1301-bc; B08-1302-bc; B08-1303-bc; B08-1305-bc; B08-1306-bc; B08-14; B08-15; Belgica; BG08/13a; Giant box corer; GKG; Gulf of Biscay; HERMIONE; Hotspot Ecosystem Research and Mans Impact On European Seas; Remote operated vehicle; ROV
Type:
Dataset
Format:
application/zip, 6 datasets
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