Preface The expedition ARK XIX/3 with the German icebreaking RV ...

faunal distribution. Palaentological studies that can reveal the changes in
environmental conditions such as current systems and interaction of different water
masses in the area can indicate which the main factors that influence Lophelia
abundance are. A comparison between Lophelia’s optimal environmental conditions
and that of the gorgonians found on the mound (which seem to be quite abundant
here) can provide further indications to what are the reasons for the poor Lophelia
coral presence in the area.
A. 4.4.4 Biogeoprocesses along the "Scarp mounds" transects
Wheeler, A., Roberts, M.
On the longest dive of the cruise (Fig. A4.4.4-1), "Victor 6000" surveyed one of the
main points of interest for the cruise – a scarp that runs for a distance of 21 km
(although intermittently in places as we discovered) at around 53 43.7’N 13 59’W.
Former acoustic surveys (TOBI side-scan sonar and Geological Survey of Ireland
multibeam echosounder bathymetry) had thrown-up questions as to the origin of this
scarp. The coincidence of the scarp with Rockall Trough boundary faults implied that it
maybe of tectonic origin. If so, then it was tantalising to assume that the carbonate
mounds that are imaged on this mound may be related to hydrocarbon seepage along
these boundary faults. A particular objective of this dive was therefore to assess the
interplay between coral communities, potential hydrocarbon seeps and the bedrock
geology of the area. Using "Victor 6000" we were able to film this enigmatic yet
impressive geological feature for the first time.
Although the scarp continued for several kilometres it varied in height from a few
metres to over 10 metres in height. In some places it was terraced whilst in others it
was vertical or very steep. Carbonate mounds were also associated with the scarp in
places although were relatively inactive (dormant) at present although some isolated
coral, and other suspension feeding communities were present.
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