RRS James Cook Cruise 35, 7-19 Jun 2009. Sidescan sonar mapping of the Whittard Canyon, Celtic Margin

James Cook cruise 035 was aimed at the detailed mapping of the Whittard Canyon system along the Celtic Margin (NE Atlantic). In 12 days, &gt;700 km of track-lines were surveyed with the Towed Ocean Bottom Instrument (TOBI, carrying a 30 kHz sidescan sonar system with phase bathymetry capability, an 8 kHz chirp profiler and a magnetometer) and 6130 km2 of shipborne multibeam data was acquired over the 4 main branches of the canyon. This comprehensive and highly detailed dataset will provide new insights in canyon morphology, formation, sediment transport processes and into the resulting spatial distribution of benthic habitats. In addition, the data formed an indispensable base map for the planning of ROV dives during the follow-on cruise JC036.<br/

RRS James Cook Cruise 60, 09 May-12 Jun 2011. Benthic habitats and the impact of human activities in Rockall Trough, on Rockall Bank and in Hatton Basin.

The main aim of cruise JC060 was to carry out habitat mapping work in selected areas of the Rockall Trough, Rockall Bank and Hatton Basin in order to assess the status of different benthic habitats in relation to human activities, especially deep-sea bottom trawling. The cruise included a revisit of the Darwin Mound cold-water coral reefs, discovered in 1998 and protected in 2003, and an assessment of the status of two fisheries closure areas on Rockall Bank. In addition, two pilot studies of a more geological nature were carried out as well: one was targeting a Polygonal Fault System in the Hatton Basin, potentially linked to fluid flow, while the other focused on the history of the Rockall Bank Mass Flow.The tools used to achieve these objectives included the Autosub6000 Autonomous Underwater Vehicle (AUV), newly equipped with an EdgeTech dual frequency high-resolution sidescan sonar plus chirp profiler and a monochrome stills camera, a commercial inspection class ROV, and more traditional equipment including piston-, mega- and boxcore, CTD and shipborne multibeam (EM120 and EM710).Although the unsettled weather hampered the operations to a certain extent (including a forced return to the shelter of the Minches, resulting in an ad hoc survey of the E Shiant Bank), the cruise was a success, with 88h of ROV footage &amp; photography collected, 125km2 of seabed mapped at high resolution (metre to centimetre-scale) by the Autosub6000, 400km2 mapped with the EM710 on Rockall Bank, and 52 coring operations for geological and biological studies.The first results of the cruise stress again the importance of a sound management of the marine realm, including the deep ocean, and underline the continuous need for detailed information and high-resolution data to underpin such management

Of sands and corals : the sedimentary environment of the Darwin Mounds, N. Rockall Trough

The Darwin Mounds, small mounded features colonised by deep-water coral species such as Lophelia pertusa and Madrepora oculata, are found in the Northern Rockall Trough, at water depths between 900 and 1100 m. They were discovered in 1998 during a TOBI (Towed Ocean Bottom Instrument) 30 kHz sidescan sonar survey, where they appeared as circular to oval high-backscatter features on a generally lowbackscatter background. A typical mound can be up to 75 m across and 5 m high, and may have a scoured ‘tail’ feature of moderate backscatter in the down-current direction. High-resolution sidescan sonar and video imagery confirmed the presence of deep-water corals, and their confinement to the mounds. However, it also illustrated damage caused by deep-water trawling activities. As a result of these findings, the European Commission adopted a regulation in March 2004 to permanently ban bottom trawling from the area, while the UK government has the intention to designate the province as Special Area of Conservation under the Habitats Directive.The specific setting in which the Darwin Mounds occur, just south of the Wyville Thomson Ridge (WTR), creates a particular oceanographic regime : while most of the Continental Slope Current of the eastern Rockall margin continues its northward course across the WTR, the lower parts (<500 m) of the current are deflected to the south-west. This resulted in the formation of a sediment drift complex in the area, including a broad sheeted drift upon which upstream flank the Darwin Mounds are located. Further to the southwest, on the down-stream flank, a large field of pockmarks has also been discovered. Piston and box cores indicate that the general sedimentary sequence in the area consists of a thin upper layer of Holocene contourite sands overlying glacigenic muds. Cores in the mounds however show several meters of homogeneous sands. Masson et al. (2003) therefore proposed that the mounds might have a genetic relationship to the pockmarks, suggesting that the mounds formed as a result of fluid escape and the eruption of sand on the seafloor. Their higher elevation above the seafloor would subsequently have attracted coral colonisation. Alternatively, it is often suggested that small coral mounds can be formed through the baffling of sand by the coral framework.Detailed grainsize and mineralogical analyses of the piston and box cores reveal the nature of the sands in the area, and show a sorting effect in the down-current (SW-ly) direction throughout the Darwin Mound Province. However, they are less effective in discriminating clearly between the on-mound and off-mound sands, or between the sands of different depths within the mounds themselves. New information from highresolution TOPAS profiles and from foraminifera studies gives more insight in the mound origin and in the position of the mounds/corals within the contourite system, including the change of current regime related to the last deglaciation

RRS Discovery Cruise DY108‐109, 6 Sept - 2 Oct 2019. CLASS – Climate‐linked Atlantic System Science Darwin Mounds Marine Protected Area habitat monitoring, BioCAM ‐ first equipment trials. BLT‐ Recipes: pilot study

DY108/109 was a combined expedition, integrating a series of scientific and technological objectives related to three different projects. The main study area was the Darwin Mounds Marine Protected Area, an area of small cold‐water coral mounds in the Northern Rockall Trough, discovered by NOC scientists in 1998 and protected from bottom contact fisheries (mainly bottom trawling) since 2003. As part of the NERC CLASS programme (Climate‐Linked Atlantic Sector Science), the aim was to assess the status of the coral mounds, in order to identify and quantify any long‐term changes to this deep‐sea habitat. The mounds were surveyed with the Autosub6000 AUV (sidescan sonar), the HyBIS video platform and a series of targeted boxcores, repeating a first round of monitoring efforts undertaken in 2011 (expedition JC060). In addition, two settlement experiments deployed in 2011 were recovered on board. The second aim of the cruise was to demonstrate and test the latest innovation in survey technology as a potential new method for monitoring this type of seafloor habitat. The new BioCam system, a combined stereo camera and double laser line scanner integrated in the Autosub6000, was developed under the NERC Oceanids Marine Sensor Capital programme. BioCam enabled millimetre‐resolution 3D colour reconstructions of the seabed over areas that are an order of magnitude larger than typically covered with conventional visual methods (~30ha/day). This type of technology will revolutionise marine habitat monitoring in the future, both in terms of area covered and level of information obtained. In addition to these habitat mapping and monitoring activities in the Darwin Mound area, DY108/109 also supported two oceanographic studies of the Rockall Trough. For the NERC‐funded project BLT‐Recipes, two 24h CTD stations were occupied on the Irish margin, as pilot study to support further work in 2020 and 2021. For the oceanographic part of the CLASS programme, a number of single CTD casts were taken along the “Ellett Line”, while the turn‐around of a lander with upward‐looking ADCP was attempted. Unfortunately, investigation with the HyBIS platform confirmed that the lander was severely damaged and could not be recovered. Despite some time lost to weather and unfortunate equipment malfunctioning, the expedition was a success, with 10 HyBIS dives completed (76h seabed video), two sidescan sonar surveys repeated, 20 successful boxcores taken, sieved an analysed on board, one mooring deployed and 48 CTD casts completed. Most of all, the BioCam system performed excellently, staightaway from its first deployment, and acquired two dense grid survey datasets covering ~60ha in total. KEYWORDS Cold‐water coral, BioCam, CLASS, Marine Protected Area, Darwin Mounds, monitoring, habitat mapping, Autosub6000, AUV, Rockall Trough, Ellett Line, OSNAP, turbulent mixin

Towards a new and integrated approach to submarine canyon research. Introduction

Submarine canyons, steep-walled valleys that cut across virtually every continental margin around the world (Harris and Whiteway, 2011), are considered major sediment transport pathways between continental shelves and the deep sea (e.g., Shepard, 1963 and Puig et al., 2014). Owing to their steep topography and high terrain heterogeneity, in addition to their unique current patterns and episodic down-canyon flushing events, which result in locally increased nutrient concentrations and food availability, submarine canyons are often considered as biodiversity hotspots (e.g., Tyler et al., 2009 and De Leo et al., 2010). On the other hand, considerable differences have been observed between individual canyon systems, and between different faunal groups in terms of their response to the typical canyon environment (e.g., Cunha et al., 2011, Ingels et al., 2011 and Schlacher et al., 2007). Unfortunately, in addition to transporting sediment, submarine canyons also tend to funnel our human litter and pollutants into the deep sea, extending the anthropogenic impact on the oceans far beyond our shores (e.g., de de Jesus Mendes et al., 2011, Mordecai et al., 2011 and Schlining et al., 2013)

RRS James Cook Cruise 124-125-126 09 Aug-12 Sep 2016. CODEMAP2015: Habitat mapping and ROV vibrocorer trials around Whittard Canyon and Haig Fras

The main aim of JC125 was to carry out habitat mapping work in the Whittard Canyon, NE Atlantic, in order to obtain a better insight in the biodiversity patterns, benthic habitat distributions and sediment transport processes of submarine canyons. At the same time, the objective was also to test a number of novel habitat mapping techniques, including sideways multibeam mapping of steep and overhanging cliffs using the Autosub6000 AUV (Autonomous Underwater Vehicle), which was specifically adapted for this task. The four-week expedition was the second cruise of the CODEMAP project (COmplex Deep-sea Ecosystems: Mapping habitat heterogeneity As Proxy for biodiversity), funded by the European Research Council (Grant No 258482). Two short ‘tag-on’ cruises were added to this main expedition: JC124 covered four days of seabed monitoring in the Haig Fras and Canyons Marine Conservation Zones as part of the DEFRA-funded project “Novel AUV and Glider deployments to inform future MPA and MSFD monitoring strategy in UK shelf waters?”. JC126 consisted of three days of ROV vibrocorer trials for the NERC-funded technology grant NERC Grant NE/0176581. Together, the five-week voyage was nick-named ‘CODEMAP2015’. To achieve its goals, CODEMAP2015 made extensive use of deep-water marine robotics: in a first for UK science, the Autosub6000 AUV, the Isis ROV (Remotely Operated Vehicle) and a Seaglider provided by the University of East Anglia were operating in the canyon, simultaneously, deployed from the RRS James Cook. They provided an unprecedented insight in the structure and processes of the submarine canyon. The nested survey design that was adopted throughout the cruise combined canyon-wide shipboard and glider surveys with AUV-based acoustics and ROV-based multibeam and HD video recordings. This enabled the integrated observation of different canyon processes at the scale they occur, ranging from 10s of km to a few mm