RRS Charles Darwin Cruise 119C Leg B, 13 Aug - 14 Sep 1999. White Zone (WhiZ) environmental survey: seabed survey of the deep waters to the north and west of Shetland

This cruise formed part of the continuing Atlantic Margin Environmental Survey (AMES). The objectives of the cruise were: a) to complete TOBI sidescan sonar survey of the “White Zone”, begun on RRS Charles Darwin cruise 119C Leg A; b) to carry out photographic surveys of the “White Zone” to ground truth the sidescan sonar imagery and provide an assessment of the seabed fauna; and c) to carry out seabed sampling to further ground truth the sidescan sonar imagery and generate samples for the future analysis of selected environmental parameters (hydrocarbons, elements, particle size). The cruise was undertaken in three phases: I) seabed photography and sampling of the southern “White Zone” area (Wyville Thomson Ridge and adjacent areas of the Faroe Bank Channel and Faroe-Shetland Channel) surveyed by TOBI during RRS Charles Darwin cruise 119C Leg A; II) TOBI survey of the central Faroe-Shetland Channel, Faroe Slope and an area north of Shetland; and III) seabed photography and sampling of the areas surveyed by TOBI during phase two. The survey encountered a very wide variety of seafloor environments, including areas of extremely dense gravel cover, areas of near complete cobble / rock / boulder cover, and a field of small barchan sand dunes on the floor (1,200m) of the Faroe Bank Channel. Two other notable TOBI features were also examined: 1. A new field of “Darwin Mounds”, in the northern Rockall Trough, with associated colonies of the coral Lophelia pertusa and populations of the xenophyophore Syringammina fragilissima. 2. Localised areas of complex seabed topography (mud diapirs), in the area north of Shetland.