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

predators and strong bottom currents. The nekton species themselves grow
only on dropstones, but not on the sandy sediments that surround it. The
dropstones are an ‘oasis’ that provides a hard substrate and also elevate
the substrate feeders over the bottom, thus protecting it from the damaging
influence of the sand particle transport that occurs near the surface.
- Fishing lines and trawl marks – this category includes areas on the
seabed where evidence of fishing impact on the benthic communities was
observed. Fishing lines lying on the bottom of the sea with coral debris and
even live corals ( as it was in the center of the mound) , plough marks from
the trawling and other damage on the seabed was observed in there areas.
In some cases the fishing lines provided a hardsubstrate for different nekton
species that grow on top of them, creating an artificial habitat. This indicates
the flexibility and readiness of the studied benthic fauna to use new habitats.
Percentage distribution of benthic communities
The high percentage of fishing line and trawl marks in the diagram (Fig. A4) is due to
the long time that the ROV spent in the area where these artifacts were. If a
percentage distribution based on the actual territory of the different categories was
made the weight of this category would be much less, probably smaller than that of
the major benthic communities in the diagram. Such a diagram would require more
advanced data processing that cannot be performed for now.
The predominant communities are that of patches of Lophelia (12,5%) and gorgonians
(14,7%), followed by the stylasterids field (10,3%) and the dropstone communities
(8,6%). The dense and total coral coverage that were so typical in previously studied
mounds on the "Polarstern" XIX/3a cruise, such as the "Belgica mounds", are
underrepresented on this mound – total coverage is 0,98% ( one occurrence on the
S - slope of the mound ), dense coverage – 2,5%. This result indicates that the
environmental conditions on the Giant Mound are not suitable for Lophelia growth.
The high percentage of gorgonian fields 7,6% implies that the mounds provide more
suitable conditions for the growth of this suspension feeder. A comparison of the
ecological requirements of Lophelia and gorgonians can provide some explanations
for why Lophelia is so scarce on the "Giant mound".
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