National Oceanography Centre, Southampton
Cruise Report No. 66
RRS Discovery Cruise DY108‐109
6 SEPTEMBER – 2 OCTOBER 2019

CLASS – Climate‐linked Atlantic System Science
Darwin Mounds Marine Protected Area habitat monitoring,
BioCAM ‐ first equipment trials
BLT‐ Recipes: pilot study
Principal Scientists

V A I Huvenne & B Thornton

National Oceanography Centre, Southampton
European Way
Southampton
Hants SO14 3ZH UK
Tel: +44 (0)023 8059 6020
Fax: +44 (0)023 8059 6554

Email: vaih@noc.ac.uk

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© National Oceanography Centre, 2020

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DOCUMENT DATA SHEETAUTHORHUVENNE, V.A.I. & THORNTON, B.

PUBLICATION
DATE
2020

TITLE
RRS Discovery Cruise 108, 6 September ‐ 2 October 2019. Darwin Mounds Marine Protected Area habitat
monitoring, BioCAM equipment trials and BLT pilot study

REFERENCE
Southampton, UK: National Oceanography Centre, Southampton, 224pp.
(National Oceanography Centre Cruise Report, No. 66)
ABSTRACTDY108/109 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 coralmounds, in order to identify and quantify any long‐term changes to this deep‐sea habitat. The mounds were surveyed with theAutosub6000 AUV (sidescan sonar), the HyBIS video platform and a series of targeted boxcores, repeating a first round ofmonitoring efforts undertaken in 2011 (expedition JC060). In addition, two settlement experiments deployed in 2011 wererecovered 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 scannerintegrated 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 typicallycovered 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 divescompleted (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 mixing
ISSUING ORGANISATION National Oceanography Centre
University of Southampton Waterfront Campus
European Way
Southampton SO14 3ZH UK
Tel: +44(0)23 80596116 Email: nol@noc.soton.ac.uk
A pdf of this report is available for download at: http://eprints.soton.ac.uk

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Contents
1.

PARTICIPANTS ................................................................................................................................. 9
1.1.

SCIENTIFIC PERSONNEL ........................................................................................................... 9

1.2.

SHIPS OFFICERS AND CREW .................................................................................................... 92.

ITINERARY ..................................................................................................................................... 113.

BACKGROUND AND SCIENTIFIC RATIONALE ................................................................................. 12
3.1.

4.

CLASS programme: sustained observations and technological development ..................... 12

3.1.1.

Darwin Mounds (Brian Bett, Hayley Hinchen, Veerle Huvenne) ................................... 13

3.1.2.

OSNAP/Ellett Line (Sam Jones)...................................................................................... 19

3.2.

BioCam (Blair Thornton & BioCam team) ............................................................................. 19

3.3.

BLT Recipes (Alberto Naveira Garabato, Eleanor Frajka‐Williams) ...................................... 19

OBJECTIVES ................................................................................................................................... 21
4.1.

Cruise aims for CLASS ............................................................................................................ 21

4.1.1.

Darwin Mounds re‐visit ................................................................................................. 21

4.1.2.

Ellett Line....................................................................................................................... 21

4.2.

Cruise aims for BioCam ......................................................................................................... 21

4.3.

Cruise aims for BLT ................................................................................................................ 22

5.

NARRATIVE .................................................................................................................................... 23

6.

METHODS AND INITIAL RESULTS .................................................................................................. 34
6.1.

Acoustic mapping & profiling (Tim Le Bas, Catherine Wardell) ............................................ 34

6.1.1.

Shipboard Multibeam Systems: EM122 and EM710 .................................................... 34

6.1.2.

Shipboard SBP System .................................................................................................. 36

6.1.3.

Autosub 6000 Sidescan ................................................................................................. 36

6.1.4.

Autosub 6000 SBP ......................................................................................................... 38

6.2. BioCAM‐based mapping (Blair Thornton, Adrian Bodenmann, Miquel Massot, Jose
Cappelletto, Takaki Yamada, David Stanley) .................................................................................... 41
6.2.1.

Description of the device .............................................................................................. 41

6.2.2.

Method to collect data ................................................................................................. 42

6.2.3.

Autosub6000 dives with BioCam .................................................................................. 47

6.2.4.

Results ........................................................................................................................... 56

6.2.5.

Conclusion and future recommendations .................................................................... 62

6.3. Megafauna community study from seabed observations (Nils Piechaud, Guillem Corbera,
James Strong, Brian Bett) .................................................................................................................. 66
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6.3.1.

Dive 51: Darwin Mounds East (1050 – 1058 m; moderate visibility and current strength)
66

6.3.2.
Dive 52: Darwin Mounds West (969 m; moderately poor visibility and high current
speeds ‐ spring tide) ...................................................................................................................... 68
6.3.3.
Dive 53: Darwin Mounds East (952 m; moderately poor visibility and high current
speeds ‐ spring tide) ...................................................................................................................... 68
6.3.4.
Dive 54: Darwin Mounds West (945 – 965 m; moderately poor visibility and high current
speeds ‐ spring tide) ...................................................................................................................... 69
6.3.5.
Dive 55: Darwin Mounds West (963 – 971 m; moderately poor visibility and high current
speeds ‐ spring tide) ...................................................................................................................... 71
6.3.6.

Dive 56: Darwin Mounds East (1045 – 1058 m; moderate visibility)............................ 73

6.3.7.

Dive 57: Darwin Mounds West (958 – 973 m; moderate visibility) .............................. 76

6.3.8.

Dive 58: North of Darwin Mounds West (965 ‐ 980 m; moderate currents and visibility)79

6.3.9.

Dive 59: North of Darwin Mounds West (943 ‐ 961 m; moderate to high visibility) .... 82

6.3.10.

Dive 60: North of Darwin Mounds East (1048 ‐ 1060 m, moderate to high visibility).. 85

6.3.11.

Dive 61: North of Darwin Mounds West (902 ‐ 924 m; moderate to high visibility) .... 87

6.4.

Macrofauna community study from boxcores (Laurence De Clippele, Laura Duran Suja) ... 90

6.5.

Settling experiment (James Strong) ...................................................................................... 99

6.5.1.

Recovered settlement moorings................................................................................... 99

6.5.2.

In situ observations of the settlement panel moorings remaining in place ............... 106

6.5.3.

Initial impressions of the fouling growth present at both sites .................................. 108

6.5.4.

Deployment of new settlement experiment .............................................................. 109

6.6.
Bett)

6.6.1.

Shipboard ADCP measurements ................................................................................. 110

6.6.2.

Water column structure in the Darwin Mounds ......................................................... 113

6.6.3.

OSNAP ADCP lander .................................................................................................... 118

6.6.4.

Darwin Mounds long‐term mooring (DY108‐048) ...................................................... 124

6.7.
7.

Water column study from CTDs, ADCP, mooring, sediment trap and lander (Sam Jones, Brian
110

Outreach activities (Larissa Macedo, Loïc Van Audenhaege) ............................................. 130

EQUIPMENT & SAMPLING REPORTS ........................................................................................... 134
7.1.

Autosub6000 Cruise Report ................................................................................................ 134

7.1.1.

Autosub 6000 Cruise Summary ................................................................................... 134

7.1.2.

AUV Standard Sensor Configuration ........................................................................... 138

7.1.3.

AUV Biocam Configuration ......................................................................................... 139

7.1.4.

Mission M150 Summary ............................................................................................. 139

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7.1.5.

Mission M151 Summary ............................................................................................. 144

7.1.6.

Mission M152 Summary ............................................................................................. 149

7.1.7.

Mission M153 Summary ............................................................................................. 153

7.1.8.

Mission M154 Summary ............................................................................................. 157

7.1.9.

Mission M155 Summary ............................................................................................. 158

7.1.10.

Mission M156 Summary ............................................................................................. 163

7.2.

HyBIS System Cruise Report ................................................................................................ 168

7.2.1.

Cruise Outline.............................................................................................................. 168

7.2.2.

Stats............................................................................................................................. 168

7.2.3.

Mobilisation ................................................................................................................ 168

7.2.4.

De‐Mobilisation........................................................................................................... 169

7.2.5.

Deep Tow Cable .......................................................................................................... 169

7.2.6.

HyBIS System ............................................................................................................... 170

7.2.7.

HyBIS specific operations ............................................................................................ 174

7.2.8.

HyBIS Media Data........................................................................................................ 180

7.3.

Coring .................................................................................................................................. 181

7.3.1.

Boxcorer ...................................................................................................................... 181

7.3.2.

Megacorer ................................................................................................................... 181

7.4.

CTD ...................................................................................................................................... 183

7.4.1.

CTD system configurations ......................................................................................... 183

7.4.2.

Technical detail report ................................................................................................ 184

7.4.3.

Configuration files ....................................................................................................... 186

7.4.4.

SENSOR INFORMATION............................................................................................... 194

7.5.

Mooring............................................................................................................................... 196

7.5.1.

SBE37........................................................................................................................... 196

7.5.2.

ADCP 600KHz Workhorse Sentinel.............................................................................. 196

7.5.3.

Sediment trap ............................................................................................................. 196

7.5.4.

Instrument Log ............................................................................................................ 196

7.6.

Ship‐fitted Systems ............................................................................................................. 200

7.6.1.

Scientific Computer Systems....................................................................................... 200

7.6.2.

Instrumentation .......................................................................................................... 202

8.

REFERENCES ................................................................................................................................ 211

9.

STATION LIST ............................................................................................................................... 214

10.

MAPS ....................................................................................................................................... 216

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PARTICIPANTS
1.1. SCIENTIFIC PERSONNEL
name
Veerle
Blair
Brian
James
NoelieAdrianJose
Guillem
Laurence
Laura
HinchenSamTim
Larissa
Miquel
Nils
David
Loïc
Catherine
Takaki
Dave
RichardPhil
Jeffrey
MartinRussell
RachelEmre
Eoin
Richard
WilliamOwain

surnameHuvenneThornton
BettStrong
BenoistBodenmann
CappellettoCorberaDe Clippele
DuranHayleyJones
Le BasMacedoMassotPiechaud
Stanley
Van Audenhaege
Wardell
YamadaTurnerAustin Berry
BagleyBensonBridger
Locke
Marlow
Mutlu
O hObain
Philipps
Platt
Shepherd

institute
NOC
USotonNOC
NOC
NOC
USotonUSoton
NOC
UEdin
UEdin
JNCC
SAMS
NOC
UCC
USotonNOC
USotonNOC
NOC
USotonNMF‐MARSNMF‐MARSNMF‐MARSNMF‐MARSNMF‐MARSNMF‐MARSNMF‐MARSNMF‐MARSNMF‐MARSNMF‐MARSNMF‐MARSNMF‐MARS

Role
PSO
Co‐PSO
Biologist/watch leader
Habitat mapper/watch leader
Biologist
BioCAM team
BioCAM teamBiologist
Biologist
Biologist
Policy observer, whale watching
Oceanographer
Geophysical processing
Irish representative
BioCAM team
Habitat Mapper/Biologist
BioCAM team
Habitat Mapper
Geophysical processing
BioCAM teamHyBIS/TLO
Autosub
Autosub
CTD
IT/systems
HyBIS
Autosub
HyBIS
Autosub
Coring
CTD/Mooring
Autosub / C‐Worker

1.2. SHIPS OFFICERS AND CREW
StewartPhilipDeclan
Simon
Gary
Edin
Gavin
Dean
CharlesGrahamStephen

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MackayGauld
Morrow
Willcox
McCoy
Silajdzic
Nicholson
Clements
Fisher
Bullimore
Smith

MasterChief Officer
2nd Officer
3rd Officer
Chief Engineer
2nd Engineer
3rd Engineer
3rd Engineer
ETO
PurserChief Petty Officer ‐ ScientificPage 9 of 224

Stuart
Christopher
Brian
Gary
David
Ryan
Derek
Peter
Christopher
Jane
DenzilCruise report No. 66

CookPeppinContehCrabb
MacKenzie
Paris
MackayLynch
Keighley
Bradbury
Williams

Chief Petty Officer ‐ Deck
Petty Officer ‐ Deck
Engine Room Petty Officer
Seaman Grade 1A
Seaman Grade 1A
Seaman Grade 1A
Seaman Grade 1A
Head Chef
Chef
Steward
Assistant Steward

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2. ITINERARY
Departure Southampton:
Arrival Southampton:

6 September 2019, time: 07:20 BST
2 October 2019, time: 14:15 BST

Fig. 2.1 Cruise track chart

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3. BACKGROUND AND SCIENTIFIC RATIONALE
Expedition DY108‐109 combined research activities for three major NERC projects: the National
Capability Programme CLASS, the project BioCAM, part of the OCEANIDS programme, and the NERC‐NSF joint project BLT‐Recipes.

3.1. CLASS programme: sustained observations and technological development
CLASS (Climate Linked Atlantic Sector Science; https://projects.noc.ac.uk/class/) is the National
Capability Single Sector Marine Research Programme funded by NERC for the period 2018‐2023. It
aims to deliver the knowledge and understanding of the Atlantic Ocean system that society needs tomake evidence‐based decisions regarding ocean management. CLASS will address key knowledge gaps
in the understanding of ocean variability, climate regulation and ocean services, and will assess how
the ocean will evolve as a result of climate change and intensified human exploitation.
CLASS is being delivered through the combination of an Atlantic focussed science programme, and aseries of activities that underpin Marine Science within the UK: sustained ocean observations in the
Atlantic, world class model development, and state of the art technology.
The objective behind the CLASS sustained ocean observations is to create and expand multi‐decadal
records of ocean parameters that provide insights in the temporal evolution of the Atlantic, from thesurface to the seafloor, and from the coast to the deep sea. The programme includes a number of
repeat transects across the Atlantic, a number of fixed‐point water column observatories, and anumber of repeat seafloor & habitat monitoring sites. The latter include sites from the shelf (Western
Channel Observatory, Haig Fras Marine Conservation Zone), slope (Darwin Mounds Marine Protected
Area, Whittard Canyon & Canyons Marine Conservation Zone) and abyssal plain (Porcupine Abyssal
Plain), which will be surveyed on a regular basis (yearly for the WCO and PAP, every 3 years for Haig
Fras, every 5 years for Whittard Canyon and every 8 years for the Darwin Mounds).
As part of the science programme within CLASS, the results of those repeat surveys will be used tocreate an improved understanding of the role and impact of abrupt seafloor disturbances on benthic
communities, including their resilience and recovery; looking both at natural and anthropogenic
disturbance events. The impact of human activities in the marine environment is extensive andincreasing, as countries around the world develop their blue economies. Direct impacts, such as
fishing, drilling, mining or the construction of seafloor installations, can have long‐term effects onbenthic communities, exceeding the natural levels of variability and disturbance those communities
are adapted to. However, because direct impacts are often related to specific events or pressures,
direct impacts are often manageable through marine spatial planning, such as the designation offishery closures or establishment Marine Protected Areas. Correct information and knowledge about
the long‐term evolution and/or recovery of benthic systems following major disturbances hence isparamount to support effective marine spatial planning.
The work during DY108‐109 covered two aspects of the CLASS programme: the repeat observation of
the status of the Darwin Mounds MPA, and the servicing of one of the essential landers measuring theoverturning in the Rockall Trough.

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3.1.1. Darwin Mounds (Brian Bett, Hayley Hinchen, Veerle Huvenne)
The Darwin Mounds Marine Protected Area (MPA) lies at the north end of the Rockall Trough locatedapproximately 160 km north west of Cape Wrath, Scotland, with depths ranging between 710‐1129m.
The site is an extensive area of sandy mounds, each of which is capped with multiple thickets of various
species of cold‐water coral. Each of the mounds is approximately 100m in diameter and 5m high, anddistinguished by a 'tail' feature visible on sidescan sonar imagery. Hundreds of mounds lie within thesite boundary, but two particularly dense fields of mounds are present to the north east and northwest limit of the area (Bett, 2001).
Finding of the Darwin Mounds site (1998)
The story begins on board RV Colonel Templer in May 19981, with that vessel engaged in a wide area
survey of the deep waters of the UK Atlantic Margin, in particular those areas being licensed for deep‐
water oil exploration, known as the 17th round Tranches (Masson & Jacobs, 1999). The survey was
being carried out with NOC’s Towed Ocean Bottom Instrument (TOBI), a deep towed sidescan sonarvehicle fitted with a 30 kHz sonar array and a 7.5 kHz sub‐bottom profiler. Through Monday 25 to
Sunday 31 May 1998, the TOBI vehicle completed four survey lines, the northern ends of which
covered the area now known as the Darwin Mounds.
At around the same time, the RRS Charles Darwin2 was setting sail from Fairlie to begin phase two of
the same wide area survey (Bett, 1999). The two cruises were staggered in time to allow the teamonboard the RV Colonel Templer to complete a preliminary TOBI map and send an interpretation to
the team on the RRS Charles Darwin that would guide their seabed sampling and photography efforts.
The TOBI science team, led by Doug Masson and Colin Jacobs, reported “individual targets … theprofiler shows them to be positive relief features of 2‐5 m in height and around 200 m in diameter.
They occur at about 1,000 m water depth. Our preliminary interpretation is that they are likely to bebiogenic mounds or small mud volcanoes”.
Their description continued “region is punctuated by a large number of discrete high backscattertargets, centred approximately on 59° 42.0’ N 07° 26.0’ W; most are a few to tens of metres indiameter … the strength of the backscatter suggests that they are some form of hard material andmay be biogenic mounds … In the extreme north of the area, we mapped a number of ‘Haloed’
features ‐ circular to subcircular areas of high acoustic backscatter with areas of moderately highbackscatter forming ellipses in an apparent down‐current (alongslope) direction ... The central part ofeach target shows small shadows on their far sides indicating that they have some relief” (Figs. 3.1 &3.2).
Finding coral in the Darwin Mounds West Field (1998)
The team onboard RRS Charles Darwin, led by Brian Bett, arrived in the area on Wednesday 3 June,
and were able to locate seabed mound targets on the ship’s fitted 10 kHz echo sounder. The following

1

All data and survey results presented herein were acquired during a wide area survey project undertaken in1998 on behalf of the Atlantic Frontier Environmental Network (AFEN). AFEN comprises: Agip (UK) Ltd.,
Amerada Hess Ltd., Amoco (UK) Exploration Company Limited, ARCO British Ltd., BG E&P Ltd., BP Exploration
Operating Company Ltd., Chevron U.K. Ltd., Conoco (U.K.) Ltd., Deminex UK Oil and Gas Limited, Elf
Exploration UK plc., Enterprise Oil plc., Esso Exploration and Production UK Ltd., Fina Exploration Ltd.,
Marathon Oil UK Ltd., Mobil North Sea Ltd., Phillips Petroleum Company U.K. Ltd., Saga Petroleum Ltd., Shell
U.K. Exploration and Production , Statoil Ltd., Texaco Britain Ltd., Total Oil Marine plc., Joint Nature
Conservation Committee, Fisheries Research Services, and the Department of Trade and Industry.

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day, Thursday 4 June, the NOC Wide‐Angle Seabed Photography (WASP) vehicle was deployed (station
54565#1) and towed across two mounds “Video shows areas of rippled sand, what appear to be‘miniature terraced hillsides’, and at one point on each mound occurrences of coral”. On Saturday 6
June, WASP was deployed (stn 54569#1) in the vicinity of a mound and the video shows “dense
populations of xenophyophores”. WASP is deployed again (stn 54574#1) “During the run two moundtops are covered on the echo sounder. This run produces the best video yet, which confirms that WASP
ran over two mound top features” (i.e. Lophelia pertusa, now classified as Desmophyllum pertusum,colonies were seen on both mounds).

Fig. 3.1 Preliminary interpretation of TOBI sidescan sonar survey from RV Colonel Templer,note the “Haloed” mounds, the area now known as the Darwin Mounds West Field.

Fig. 3.2 Example of TOBI sidescan sonar image from RV Colonel Templer showing mounds (arrowed)
and tails (T) in the area now known as the Darwin Mounds West Field.

The RRS Charles Darwin cruise report concludes that “observations made around the seabed moundsof the 'haloed mounds' region suggest that appreciable biological zonation may attend these features... aggregations of coral colonies and xenophyophores appear to be associated with the mounds”. It

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was at around this time that the term ‘Darwin Mounds’ came in to use. The link between the ship andthe mounds continued in the following two years.
Finding coral in the Darwin Mounds East Field (1999)
In 1999, the RRS Charles Darwin returned to the area, with a team led by Brian Bett and Colin Jacobs
engaged in another wide area survey of the deep waters of the UK Atlantic Margin as part of the DTI’s(now BEIS) Strategic Environmental Assessment process (Bett & Jacobs, 2007) 2. This enabled a brief
visit to the area now known as the Darwin Mounds East Field. On Sunday 15 August, “Echo sounding
confirms presence of seabed mounds of a similar character to the ‘Darwin Mounds’. WASP is thendeployed at Site A as station 55002#1 … Video shows corals and xenphyophores as expected, though
the ground does appear a little different to the ‘Darwin Mounds’ sites previously studied … A new fieldof ‘tailed’ mounds … with associated colonies of the coral Lophelia pertusa [Desmophyllum pertusum]
and populations of the giant protozoan Syringammina fragilissima … Depth c. 1050 m … Presence ofa number of cobbles and rocks marks the ground as a little different from the western Darwin Mound
field”.
Finding coral in the Darwin Mounds Mini Field (“pocket mounds” 2000)
In the year 2000, the RRS Charles Darwin was back again (Bett, 2007) 3, making an unusual rendezvous
at sea with the RRS Discovery (III) in the Darwin Mounds West Field area on Sunday 23 July. RRS
Discovery had been on site since 9 July, with a team led by Paul Tyler (University of Southampton)
engaged in the first full science cruise to the Darwin Mounds area. The ships parted to continue theirrespective operations, with the RRS Charles Darwin returning to the area on Monday 31 July toinvestigate the Darwin Mounds ‘mini‐field’, an apparently isolated pocket of Darwin Mounds to thenorth of the East Field that were imaged during a TOBI survey in 19994. The WASP vehicle was
deployed (Site WTS8; stn. 55254#1) “footage obtained … shows the expected presence of Lophelia[Desmophyllum] and xenophyophores, but also appears to show evidence of trawl damage to the coral
communities”. An observation that the work onboard RRS Discovery (III) was to expand on.
Starting the detailed science of the Darwin Mounds (2000)
The RRS Discovery (III) visit to the Darwin Mounds in the year 2000 represented the start of detailed
scientific investigations at the site (Bett et al., 2001). This effort was funded by NERC, with additional
support from two European Union funded programmes, ACES5 and ECOMOUND6. The programme ofwork encompassed: seabed photography using the NOC SHRIMP (Seafloor High Resolution IMaging
Platform) vehicle and Bathysnap time‐lapse camera system, biological seabed sampling (multiple
corer, box corer, Agassiz trawl), geological seabed sampling (piston corer, giant gravity corer), seabedimaging by high frequency (100 and 410 kHz) sidescan sonar, and oceanographic observation by CTD
and moored current meters. This detailed investigation, together with the earlier surveys, resulted in2

All data and survey results presented herein were acquired during a wide area survey project undertaken in1999 on behalf of the UK Department of Trade and Industry. The project was carried out as a joint venture
between the George Deacon and Challenger Divisions of the Southampton Oceanography Centre and wasmanaged by Geotek Ltd.
3
The primary survey data presented herein were acquired during a wide area survey project undertaken in2000 on behalf of the UK Department of Trade and Industry. The project was carried out as a joint venture
between the George Deacon and Challenger Divisions of the Southampton Oceanography Centre and wasmanaged by Geotek Ltd.
4RRS Charles Darwin cruise 119A, Principal Scientist Douglas Masson
5
EU 5th Framework project “Atlantic Ecosystem Study”, contract number EVK3‐CT‐1999‐00008
6
EU 5th Framework project “Environmental Controls on Carbonate Mound Formation” contract number EVK3‐
1999‐00061
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numerous scientific publications, most notably Bett (2001), Masson et al. (2003) and Wheeler et al.
(2005).
Bett (2001) provides the first formal publication of the name “Darwin Mounds” and an initialassessment of the comparative ecology of mounds, tails, and the background sedimentary
environment, noting the apparent association of Lophelia pertusa [Desmophyllum pertusum] colonies
with mounds, and abundant Syringammina fragilissima populations with the mounds and their tails.
Masson et al. (2003) gives a detailed account of the mounds, the wider seafloor environment, andtheir potential mechanism of formation, and serves as a synthesis of the 1998‐2000 studies. Wheeler
et al. (2005) revealed that in 2000 the Darwin Mounds had already been impacted by commercial
demersal trawling activities, with near‐complete destruction of some mounds.

Fig. 3.3 Sidescan sonar imagery illustrating the appearance of a “healthy” coral mound vs. trawledcoral mounds. From Wheeler et al. (2005). Dark tones represent high acoustic backscatter
The UK’s first deep‐water marine protected area
Cold‐water corals are considered to form vulnerable marine ecosystems that require protection(UNGA, 2006), and deep‐water reefs may be specifically protected under Annex I of the EC Habitats
Directive7. The high‐resolution sidescan sonar and video data that illustrated impacts from bottom
trawling in the Darwin Mounds were therefore of concern. Those observations, together with the factthat at the time of their discovery, the Darwin Mounds were the only example of Lophelia[Desmophyllum] colonies growing on sandy rather than rocky substrata, were important in driving the7

Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna andflora, O.J. L206, 22.07.92
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development of a conservation policy. This was not entirely straightforward (see timeline tablebelow). It started with an emergency closure of the area under the EU Common Fisheries Policy inAugust 2003, that was made permanent in March 2004 (De Santo & Jones, 2007). The Darwin Mounds
then became the UK’s first offshore MPA, and were subsequently designated as a Special Area ofConservation under the EC Habitats Directive on 17 December 2015. The implementation of these
protection measures is managed by the UK's Joint Nature Conservation Committee (JNCC) and Marine
Scotland. Unfortunately, evidence from VMS data seemed to suggest that trawling pressure directly
before the fisheries closure was high, particularly in the Eastern Darwin Mounds (Davies et al., 2007).
Timeline of Darwin Mounds MPA Designation
1998 May

Discovery of the Darwin Mounds

1999 Nov

The “Greenpeace Judgment”, UK required to extend Habitats Directive offshore

1999

JNCC begin identifying offshore Natura 2000 sites (Johnston et al., 2001)

2000 Jul

Darwin Mounds revisited, trawling damage detected2000 Jul

European Commission (EC) requested ICES to provide advice on cold‐water corals

2001 early

UK Secretary of State commits to protecting Darwin Mounds as an MPA

2002 May

WWF‐UK Report on a Darwin Mounds Special Area of Conservation (Gubbay et al., 2002)

2002 Oct

UK approaches EC regarding protecting Darwin Mounds

2003 Jan

Revised Common Fisheries Policy (CFP) Regulation 2371/2002 – a mechanism for emergency closure

2003 Jun

UK requests action under CFP Regulation 2371/2002

2003 Aug

Emergency closure (Regulation 1475/2003)

2003 Sep

Proposal for permanent Regulation submitted

2004 Feb

Emergency closure extended six months (Regulation 263/2004)

2004 Mar

Closure made permanent (Regulation 602/2004)2015 Dec

Designation of The Darwin Mounds Special Area of Conservation

Darwin Mounds protection today
The coral thickets qualify as Annex I Reef according to the European Commission interpretation. The
occurrence of Lophelia pertusa reef as thickets capping sandy mounds is believed to be unique due tothe particular geological processes which formed the mounds and the fact that the coral is growing
on sand rather than a hard substratum (Masson et al, 2003). The number of thickets vary per moundand may be between one and several metres wide and high.
As well as the designated cold water coral reef feature, the sandy mounds also support significant
populations of the xenophyophore Syringammina fragilissima, which is a Vulnerable Marine
Ecosystem (VME) indicator species that occurs in particularly high densities on the mounds and thetails (Bett, 2001; Hughes & Gooday, 2004). The individual reefs on each mound provide a habitat forvarious species of larger invertebrates such as sponges and brisingiid starfish.
Continuing the detailed science of the Darwin Mounds (2011)
Following the initial research described above, the Darwin Mounds were not investigated for several
years. Only eleven years later, in May 2011, a new visit took place during expedition JC060 on board
the RRS James Cook (Huvenne, 2011). The cruise was part of the NERC MAREMAP programme, andwas also funded by the ERC Starting Grant project CODEMAP (Grant no 258482), with additional
support from JNCC and the Lenfest Ocean Program. New technologies were deployed to investigate
the coral mounds: the Autosub6000 Autonomous Underwater Vehicle (AUV) was used to produce
detailed multibeam and high‐resolution sidescan sonar maps of sections of both the Eastern andWestern Darwin Mounds, and a commercial inspection class ROV provided imaging capability. The
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dataset also included a series of boxcores and two piston cores that sampled the entire thickness of
two mounds. The analysis of these datasets (Huvenne et al., 2016; Victorero et al., 2016) taught usthat:‐ There is a reasonable compliance with the fisheries closure and MPA designation, althoughoccasional violation still occurs. A few trawl marks were observed in the sidescan sonar data, but thedensity reduced by ~90%.
‐ The cold‐water coral habitat has a low resilience and recovery potential. Heavily impacted areas
showed very little recovery and no re‐growth, eight years after their protection.
‐ The precautionary principle and swift development of conservation measures are very important fora successful conservation strategy. The Western Darwin Mounds had received less trawling impact
before the closure, and the rapid designation of the MPA meant at least that part of the coralecosystem was successfully protected. It maintained the same level of live coral occurrence asencountered in 2000.
‐ Mound initiation started in the early Holocene, with rapid mound development between 10 and
9.7ka BP, and further phases of vibrant coral growth around 8.8ka BP, 6.5 ka BP and 3.4 ka BP. After
that, coral growth declined, probably as a result of changing current regimes and a reduced food input
towards the corals.
‐ The use of autonomous and robotic vehicles was key in obtaining the detailed results, and will
become the method of choice for future monitoring of deep‐sea conservation areas.
A further expedition on board the RRS James Cook took place in the area in June 2015 (JC136 –DeepLinks expedition, Howell &Taylor, (2016)). However, the visibility at the seabed was so heavily
impacted by the presence of phytodetritus (arrival of the spring bloom), that no reliable imagery work
could be carried out.
Extending the detailed science of the Darwin Mounds (2019)
Since the last detailed survey, another eight years have passed, which means the MPA has been closed
to bottom contact fisheries for 16 years now. Hence the main aim of the CLASS work during DY108/109
is to assess the status of the Darwin Mounds MPA in terms of coral cover, coral health and community
composition.

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3.1.2. OSNAP/Ellett Line (Sam Jones)
The Scottish Continental Slope Current is a swift, narrow boundary current flowing north along thecontinental slope of the Rockall Trough, NE Atlantic (Booth & Ellett, 1983). It is found typically between
1000m and 250m depth, with its core along the 500m depth contour. The current contains thewarmest and saltiest water flowing northward across this latitude in the sub‐polar gyre. Although the
net transport of the current is small, because the temperature and salinity are much larger than the
average between Scotland and Greenland it is important for the net heat and freshwater fluxes in the
subpolar gyre.
The CLASS project is trying to continuously monitor the current as part of the international OSNAP and
CLASS programmes whose goal is to try and quantify the role of the subpolar gyre Atlantic overturning
circulation in the World’s climate. This work is a continuation of a long time series started by David J
Ellett, who established a hydrographic transect across the Rockall Trough, that has been monitored
on a close to annual basis since 1975 (Holliday et al., 2000; Johnson et al., 2010).
The aim of DY108/109 with regard to the “Ellett Line” part of the CLASS programme is the recovery ofa benthic lander system that has been out on the continental slope for one year, and the deploymentof an identical new system for the coming year. The landers were built to measure the strength,
structure and variability of the Scottish Continental Slope Current.

3.2. BioCam (Blair Thornton & BioCam team)
BioCam is a seafloor imaging system being developed at the University of Southampton under NERC’s
Oceanids Marine Sensor Capital program, grant number NE/P020887/1 (2017 to 2021). BioCam
enables millimetre resolution 3D colour reconstruction of the seafloor from high altitudes of between
5‐8 m off the seafloor. This is significantly higher than conventional colour imaging systems thattypically need to operate at 2‐3 m off the seafloor. The increased swath (6‐10 m instead of 2‐3 m), andability to image from safer altitudes using faster moving vehicles (1m/s instead of 0.2 m/s) allows
BioCam to achieve area coverage rates of up to 40,000 m2/hour for a single swath transect, which ismore than an order of magnitude higher than conventional visual survey methods.
DY108/109 is the first expedition to deploy the new BioCam system, and the first where this type oftechnology is integrated into the Autosub6000. The main goal is system testing, but at the same time
the team aims to map significant proportions of the Darwin Mounds MPA, in a variety of survey
patterns, to evaluate the use of this technology for MPA monitoring and assessment.

3.3. BLT Recipes (Alberto Naveira Garabato, Eleanor Frajka‐Williams)
Since the seminal work of Walter Munk in the 1960s (Garrett & Munk, 1972), oceanographers havebelieved that the upwelling of cold, abyssal waters that regulates the deep ocean's ability to sequester
heat and carbon for decades to millennia (thereby shaping Earth's climate) is driven by centimetre‐scale turbulent mixing associated with breaking waves in the ocean interior. Measurements of deep‐
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ocean turbulence over the last two decades, however, starkly contest this scenario, and insteadsuggest that mixing by breaking waves drives downwelling of abyssal waters. Inspired by thisconundrum, recent theoretical investigations have developed a tantalising alternative view of the roleof mixing in sustaining deep‐ocean upwelling. In this new view, upwelling is driven by highly localised
turbulence within thin (typically tens of metres thick) layers near the seafloor, known collectively as
the bottom boundary layer.
BLT Recipes (Bottom‐Boundary Layer Turbulence and Abyssal Recipes; NERC grant NE/S001433/1)
seeks to test this emergent new paradigm of ocean mixing, whereby deep‐ocean upwelling is primarily
driven by bottom boundary layer turbulence instead of by breaking internal waves in the oceaninterior ‐ as has been held over the last four decades. The project will do this by: (i) measuring the net
mixing and upwelling in a deep‐ocean basin through the release of a chemical tracer (SF5CF3); (ii)measuring the contribution of interior processes to mixing and upwelling in the basin with ship‐
deployed turbulence profilers; (iii) measuring the contribution of bottom boundary layer processes tomixing and upwelling in the basin with specialised moorings and the release of a chemical dye(fluorescein); and (iv) evaluating the relative roles of interior and boundary processes in determining
basin‐scale mixing and upwelling with a high‐resolution numerical model grounded on theobservations from (i)‐(iii).
The deep‐ocean basin in which the experiment will be conducted is the Rockall Trough (RT), in the
Northeast Atlantic. The RT is an optimal choice because of its easy accessibility from western Europe,
moderate depth (which facilitates frequent sampling with ship‐deployed instrumentation), modest
mean and eddy flows (which prevent an overly rapid and widespread dispersion of the tracer), andnotable tidally‐induced deep‐ocean turbulence (which generates readily measurable signals of
turbulent mixing).
The project is an international collaboration between U.K. investigators (Prof. Alberto Naveira
Garabato and Dr. Eleanor Frajka‐Williams from the University of Southampton, and Dr. Marie‐Jose
Messias from the University of Exeter) and U.S. investigators (Prof. Raffaele Ferrari from the
Massachusetts Institute of Technology, Dr. Kurt Polzin and Dr. James Ledwell from the Woods Hole
Oceanographic Institution, and Prof. Matthew Alford and Dr. Gunnar Voet from the Scripps Institutionof Oceanography). It will entail research vessels and instrumentation from both countries.
The fieldwork for BLT‐Recipes will start in earnest in summer 2020, however cruise DY108/109
provided the unique opportunity to obtain pilot data in the Rockall Trough. Based on a number of 24h
CTD casts, planning of the further activities and expeditions for BLT‐Recipes will be improved
significantly.

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4. OBJECTIVES
4.1. Cruise aims for CLASS
4.1.1. Darwin Mounds re‐visit
The overall DY108/109 cruise aim for the CLASS programme was to identify and quantify any potentialchanges to the habitats and benthic communities in the Darwin Mounds MPA over the last 20 years.
The specific objectives were to:•Re‐map the Eastern and Western Darwin Mounds using AUV sidescan sonar to evaluate
trawling intensity & mound extent•
Re‐run the ROV video transects from 2011 to study community composition, biomass anddistribution•
Video, and if possible recover, marker bouys with settling plates left in 2011 to evaluatecolonisation & connectivity•
Deploy a short mooring with sediment trap, CTD and ADCP to quantify physical environmentand disturbance regime
Furthermore, the team supported the following collaborative work:•
Boxcoring on/off mound for macrofauna studies (UEdin)•
Megacoring inside/outside MPA for meiofauna studies (NOC/OBE)•
Collection of coral samples for connectivity studies (UPlymouth, UEssex)•
Collection of voucher specimens for taxonomic ID (if possible)

4.1.2. Ellett LineThe overall aim of the CLASS programme with regard to the long‐term observations along the Ellett
Line is to measure the strength, structure and variability of the Scottish Continental Slope Current.
The specific objectives during DY108/109 were:• Recover trawl‐resistant RTADCP Lander• Download ADCP Data
• Refurbish lander• Redeploy or deploy the new, spare lander instead
Additional objectives were:• CTD profile at lander site
• CTD profiles at other EEL stations

4.2. Cruise aims for BioCam
The DY108/109 expedition represents the first sea trials of BioCam, and the first attempt to collectcontinuous cover dense grid maps using Autosub6000. The objectives for BioCam can be split into
engineering (E) and scientific (S):

E1: Verify TRL8 (Technology readiness Level 8) of BioCam on Autosub6000 through successful
collection of datasets from 1000 m depth at Darwin mounds.
E2: Collect data for further engineering development of methods toa. improve colour and dimensional accuracy of reconstructions and AUV localization
estimates

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b. automatically classify imagery by topic and develop query algorithms to help
understand broader scale spatial patterns,
c. automatically segment features within an image frame
S1: Collect data regarding the multihectare scale area cover of cold‐water coral (GOOS EOV)
impact on local ecology
S2: Collect multihectare scale revisitable dense grid imagery suitable for temporal monitoringon future expeditions
S3: Upload imagery and metadata to community wide open access, web‐based annotation
platforms such as Squidle+

4.3. Cruise aims for BLT
BLT Recipes seeks to test an emergent new paradigm of ocean mixing, whereby deep‐ocean upwellingis primarily driven by bottom boundary layer turbulence instead of by breaking internal waves in theocean interior. To support the cruise planning for the 2020 season under the BLT‐Recipes project, theDY108/109 aims were:Specific objectives:•
24hour yoyo CTD station inside canyon•
24hour yoyo CTD station outside canyon
Additional work: additional individual CTD casts in the canyon

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5. NARRATIVE
Thursday 5 September 2019
Final day of mobilisation. All scientists arrived by lunchtime, and the last pieces of equipment,
including the equipment brought down by van from Edinburgh, loaded on board. Science meeting at
14:30BST, followed by Safety Briefing and ship familiarisation at 15:40BST. Final unpacking andsecuring equipment, ready to sail in the early morning.
Friday 6 September 2019
Fair weather, but strong winds, up to Force 6‐7 at times, calming down to Force 4 by the evening.
Shore leave finished at 06:00BST, and by 06:45BST the gangplank was taken on board. The ship left
the quayside at 07:15BST, and a smooth transit followed for the rest of the day. The EM122 and EM710
multibeam systems were switched on when entering the West Solent, and ran for the rest of the day.
The rest of the equipment was set up and prepared. A safety drill with muster took place at 16:00BST.
Saturday 7 September 2019
Fair weather with moderate winds, Force 4, sea state slight (3)Clocks changed to GMT at 02:00BST. We passed Land’s End overnight, and turned north towards the
Irish Sea, continuing the transit for the rest of the day. Further equipment was set up and tested, andscience introductions presented to colleagues and the ship’s crew.
Sunday 8 September 2019
Fair weather with moderate winds, Force 3, increasing to 5 in the evening. Sea state smooth to slight(2‐3)
The transit continued smoothly, and the team started to gear up for the first deployments andrecoveries of the cruise the next day. At 19:45z the ship was stopped shortly to lower the dropkeel inorder to be prepared for the lander recovery the next morning.
Monday 9 September 2019Partly cloudy with moderate winds, Force 5, sea state moderate (4)We continued the transit to the ADCP lander site throughout the night (Cruise RV Armstrong AR30‐
04, mooring number AR30‐04‐RTADCP1), and arrived at the waypoint 1.5nm SSE of the nominal landersite shortly after 05:00z. Steaming towards the lander site, the release was pinged and an answer
received at 05:17z. This was repeated with as we were approaching the lander site, indicating that thelander was still in the right place. However, at the same time an unnamed fishing vessel was spotted,
that was on a direct course towards the lander site. Attempts to contact the vessel were made, but
no response received. Eventually the vessel changed course slightly, but it was decided safest to wait
until this trawler had passed, before the release was triggered (07:11z). Although both releases were
triggered and reported they were open, the lander did not appear to come up. Further attempts were
made, but at 07:40z the lander was considered stuck on the seafloor and it was decided to leave thelander site.
The ship was moved 0.5nm to the west, for a short dip of the AUV to test its buoyancy. After that wemoved to WP004, 1nm SSE of the Ellett mooring at 1800m water depth, for the first CTD of the cruise(DY108‐001‐CTD01). The CTD was in the water at 09:46z, and reached the deepest point (1780m) at
10:24z. On the way up, water was collected at 1100m, while two USBL beacons and a set of acoustic
releases were tested as well). The instrument was back on deck at 11:30z.

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We then moved back to the lander location, with the aim to inspect the instrument on the seabedwith the HyBIS vehicle (DY108‐002‐HyBIS50). HyBIS was in the water at 13:30z, and descended to theseabed normally, when at 13:58z, at 423m depth, the lights dimmed and camera connections failed.
The HV switch tripped and the vehicle was powered off, and it was brought back on board at 14:22z.
No immediate fault was found with the vehicle (it ran well on the deck lead), suggesting a fault in theumbilical or power supply. The issue would require several hours to get fixed, hence we gave up on
the idea to inspect the lander with HyBIS, and decided to deploy the new lander at a location 500m
NNW along the 750m contour (DY108‐003‐ADCP01).
The acoustic release was fixed to the slings, and the whole package was lifted off the deck at 15:43z.
However, as it was lowered into the water, the floatation with ADCP disconnected and floated freefrom the concrete base plate. The plate was lifted back on board 16:13z, after which the skilful deckcrew recovered the floatation unit and brought this on deck as well (16:47z).
To finish the work for the day, a yoyo CTD cast was added to the programme (DY108‐004‐CTD02_03),
mainly to pressure test the housing of one of the BioCAM lasers, as a potential microcrack had beenspotted earlier in the day, which had to be tested before real deployment. The CTD was in the waterat 18:25z and lowered & lifted two times, before being recovered on deck at 20:05z.
After this operation we set sail for Mingulay, to run a calibration mission with BioCAM on the Autosubin sheltered waters.
Tuesday 10 September 2019
Overcast with increasing winds from Force 5‐7, sea state 3, increasing throughout the day to 5,
occasionally 6
We arrived at the Mingulay site just before 4am. The team carried out the last pre‐dive checks andtoolbox talks, and Autosub was launched at 06:41z (DY108‐005‐AUV150). The system carried out its
calibration mission exactly as planned, and we followed the vehicle on the USBL for the duration of
the mission. Autosub was back at the surface by 09:45z, and back on deck by 10:27z. By that time, thewind had picked up, and the sea state started to pick up as well. Everything was secured on deck andwe started our transit to the Darwin Mounds. With the wind and tide pushing the ship forward, we
made very good speed in the Minch. Traveling north of Lewis was a little more challenging.
Wednesday 11 September 2019Partly cloudy with strong winds , Force 5‐6, sea state 5
We arrived at the Western Darwin Mounds at 09:00z, and set up the ship for a CTD. After assessing
the weather conditions, it was decided that the sea state was workable for deployments midships
from the starboard side, but not for AUV deployments. The first station of the day (DY108‐006‐CTD04)
was a CTD, also to obtain a sound velocity profile. The CTD was deployed at 09:45z, and recovered by
10:10z. We then moved to a mound position where we attempted to take a boxcore for macrofauna
studies. Our first attempt (DY108‐007‐BC01, in water 12:00z, back on deck 13:14z) was not successful:the core did not trigger. For the second attempt (DY108‐008‐BC08, in water 13:36z, back on deck
14:40z), the trigger wire was extended a bit and the core was lowered a little faster. Some material
was recovered, but it was partly washed out. The core was sieved nonetheless, mainly as backgroundinformation. A third attempt (DY108‐009‐BC03, in the water 15:13z, back on deck 16:16z) was
considered successful, considering the type of material that we were trying to core (coral rubble in acoarse, sorted sand matrix). Once the boxcore was secured on deck, the ship went on transit to theEastern Darwin Mounds for our first HyBIS dive (DY108‐010‐HyBIS51). The EM122 multibeam system
and SBP120 sub‐bottom profiler were kept running during all operations, but data was only recorded
during transits. This approach was followed as much as possible for the next days, although

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occasionally data recording was not switched off on station, or the systems developed a fault and had
to be re‐started.
The HyBIS vehicle was deployed at 19:07z, and reached the seabed at 20:12z. We repeated the ROV
dive JC060‐117‐ROV26, and inspected one of the marker bouys deployed on the seabed in 2011. HyBIS
was operated using the active heave compensation on the winch, which improved the quality of the
footage massively.
Thursday 12 September 2019Partly cloudy with a few showers. Strong winds, force 5‐6, sea state 5
The HyBIS dive continued smoothly until 02:07z, and the vehicle was back on deck at 02:52z.The shipthen transited back to the Western Darwin Mounds to continue the boxcore work there. The first
boxcore (DY108‐011‐BC04) was deployed at 04:48z, and was back on deck by 05:48z with a successful
sample. The second boxcore (DY108‐012‐BC05) was deployed at 06:20z, and came on deck at 07:17z.
After that we moved back to the Eastern Darwin Mounds for a third boxcore (DY108‐013‐BC06), in thewater at 09:41z, back on deck at 10:51z. At that moment the weather had improved enough toconsider an Autosub deployment, and after some discussion and consultation of the weather charts,
it was decided to move back to the Western Darwin Mounds and deploy Autosub for its first science
mission (DY108‐014‐AUV151). This mission aimed to re‐survey the high‐resolution sidescan sonar
mosaic of the Western Darwin Mounds, but also included two hours of additional calibration runs for
BioCAM. The transit to the Western Darwin Mounds took longer than expected, as the ship had to sail
into the weather, but we managed to come onto station shortly after 12:45z. Autosub was released
at 13:25z, and started to dive at 13:32z. We followed the vehicle on the USBL until it reached theseabed, by which time it had drifted ~500m from the waypoint in a south‐southwesterly direction(~210°). Attempts were made to communicate with the vehicle, and to update its positional
information, but no communication link could be established. Eventually the vehicle’s programmed
waiting pattern timed out, and it started the mission at 15:45z, however with a ~500m offset
compared to the planned location.
From that point we stopped following the vehicle on the USBL, and prepared for the next activity: a
HyBIS dive (DY108‐015‐HyBIS52) to recover one of the marker buoys left in the Western Darwin
Mounds during JC060 (JC060‐030‐Mark02). The system was in the water at 17:32z, and back on deckby 19:27z after a successful mission: the 3.5m‐long marker buoy was collected and brought on deckfor sampling of the encrusting fauna. During the HyBIS dive, we also kept tracking the AUV on the
USBL system, and could see the vehicle pass by at ca. 1km distance.
With the marker buoy safely on deck, we moved back to the Eastern Darwin Mounds to pick up asimilar system there (DY108‐016‐HyBIS54, old station number: JC060‐050‐Mark04). HyBIS was in thewater at 21:21z, picked up the mooring at 22:38z, and was back on deck with the ~5m long package
at 23:26z. This mooring had two settling plates fixed to it at 1 and 2 m above the seabed, but
unfortunately the upper plate came off during recovery. However, the rest of the package was densely
encrusted with a variety of fauna, including cold‐water corals, which provided ample opportunities forsampling.
With those two rescue dives under our belt, HyBIS was reconfigured back to its normal video surveying
mode, ready for a next deployment. This took up some time, and left us with too little time for anotherdive before the change of watch. Hence the ship slowly migrated to the first boxcore station ready for
deployment in the morning.
Friday 13 September 2019
Changeable with heavy showers, strong winds, force 6 occasionally up to 7, sea state 5 occasionally up
to 6
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When the coring team came on watch at 4am, conditions had deteriorated, to the point that theboxcoring operations were called off. As the conditions did not improve during the early morning, it
was decided to go back to the Western Darwin Mounds and follow Autosub on the last section of its
mission, to obtain a better navigation correction. The transit back to the west was slow anduncomfortable, as we were going into the seas, but we arrived well in time to see the vehicle finish its
last lines of BioCAM calibrations before leaving the seabed at 11:18z. It came to the surface at 11:53z,
but was quite far away from the ship, and although occasionally a Wifi connection could beestablished, and regular Iridium positions came through, it took ~45 mins and a series of ship moves
before the vehicle was spotted in the water. At that moment, the sea state was still too rough forrecovery (wave heights around 4 m, occasionally more), and it was decided to delay the operation, as
the weather was predicted to improve. The vehicle was left drifting at the surface, and the ship kept
following it, until by ~15:30z it was decided to start the recovery. The vehicle was grappled by 16:19z,
and was successfully recovered by 16:29z. Data download started immediately, and showed themission had been a success.
By then the wind started to pick up, and given the predictions of a storm with wave heights of 7‐10m,
we turned south and sailed back to the Minch to sit out the adverse weather. Swells were alreadybuilding to such extent that the course of the ship had to be chosen carefully, and the planned
multibeam survey along a line parallel to the transit taken on Wednesday 11 Sept into the Darwin
Mounds had to be given up. The EM122 system was still kept running and recording, to obtain
opportunistic data along the transit.
Saturday 14 September 2019
Stormy weather with rain showers, strong winds, force 8 up to 9. Sea state in Broad Bay (off Stornaway)
3 to 4, calming down during the day
The ship arrived into Broad Bay at breakfast time, and sheltered for the rest of the day. The EM122
multibeam system was switched off once the ship was in the bay. The science team used the time toprocess the first Autosub data, and a few colleagues presented their work at the daily science meetingin the afternoon.
Sunday 15 September 2019Partly cloudy with sunny spells, still strong winds up to force 7. Sea state in Broad Bay 3, in Rockall
Trough 5 through transit
Following a quiet night in Broad Bay, the ship set sail at 09:23z on course for the Darwin Mounds once
again, with the aim to arrive there before 4am the next day. The early start gave the vessel the chance
to choose a course and speed that would minimise the discomfort during the transit. Following thecompulsory hour of cetacean watch, the EM122 and EM710 multibeam systems, together with the
SBP120 sub‐bottom profiler were switched on to record data during the transit. However, the sea
state was still quite rough, severely affecting the quality of the acoustic data. Despite the conditions,the ship made good progress and we approached the Darwin Mounds working area earlier than
expected.
Monday 16 September 2019Partly cloudy with sunny spells, winds easing to force 5, increasing again to 6‐7 in the late afternoon.
Sea state easing from 5 to 4, picking up shortly again in the early evening.
We arrived at the Western Darwin Mounds at ~01:30z, but decided to wait for the swell to come down
a little before deploying the CTD (DY108‐017‐CTD05). The system was in the water by 03:02z and backon deck by 04:02z. We downloaded the data and extracted the sound velocity profile in order toupdate the USBL and echosounder systems. The next operation was an Autosub deployment (DY108‐
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018‐AUV152) with the BioCAM system, aiming to create a dense grid over a section of the Western
Darwin Mounds. After the usual pre‐dive checks, the AUV was deployed at 06:39z, and started diving
at 06:50z. The vehicle was tracked on the USBL and on the tracklink system until it was close to thebottom, but like the previous dive, communications were lost just before it reached the working
altitude. Again this meant that no update on position could be sent, and the drift that had occurred
during descent could not be corrected. However, this time we had deployed the vehicle ‘upstream’ ofthe target waypoint, estimating the expected offset based on the ship‐board ADCP recordings. As aresult, the Autosub started its mission only ~60m away from the waypoint, which was an acceptableoffset. We still had to wait for the vehicle waiting pattern to time out, so it was not before ~09:12z
that the actual mission started. Just after that moment, at 09:18z, also the USBL connection with the
AUV was lost. Bar a few uncertain pings immediately after that, no further positional information wastransmitted and the connection was not restored for the rest of the mission.
We did trust that the vehicle was well underway, so moved to our first boxcore location for the day.
The boxcoring operations stayed in the Western Darwin Mounds, with the aim to potentially obtain afew USBL fixes from Autosub, which would improve the Kalman filtering of the navigation. Threeboxcores were taken over the course of the day (DY108‐019‐BC07, DY108‐020‐BC08 and DY108‐021‐
BC09), all in tail features. The operations started at 10:20z, and cores came on deck at 11:25z, 13:16z
and 15:25z. With that last core on deck, the ship was repositioned for the next HyBIS dive (DY108‐022‐
HyBIS54). The vehicle was deployed in worsening conditions at 16:50z, with the bridge reporting somedifficulties keeping position against strong winds and surface currents. On the descent, the Scorpio
camera failed shortly, but it could be restarted and a good signal was received before the systemreached the seafloor. Initially it was difficult to manoeuvre the HyBIS along the correct track, becauseof the strong currents at depth, but the conditions became better as the night went on.
Tuesday 17 September 2019Partly cloudy with moderate winds, force 3‐4. Sea state coming down from rough to moderate, 5‐4.
HyBIS was brought on deck by 02:54z, with the aim to reposition the ship back to the Autosub survey
area in an attempt to re‐establish USBL connection. However, by 03:30z a flashing light was observedat the surface, and it turned out that the vehicle had sent a first Iridium message at 03:23z. This meantthat no end‐of‐survey USBL position was obtained. The ship then approached the AUV, but it was
decided to wait with recovery until first light. Upon investigation it could be concluded that the system
had completed its mission correctly, and that the initial time estimates had been slightly wrong.
The recovery operation was started shortly before 06:00z, and by 06:15z the vehicle was back onboard. However, the conditions were still quite rough, and the recovery was not easy. The mission
was very successful, though, with a full BioCAM photo dataset recovered.
Once Autosub was back on board, we repositioned for a series of boxcores in the Western Darwin
Mounds. (DY108‐023‐BC10, DY108‐024‐BC11, DY108‐025‐BC12, DY108‐026‐BC13). The first core wasin the water at 08:16z, and the coring operations finished by 14:43z. After that we repositioned for a
new HyBIS dive (DY108‐027‐HyBIS55), repeating ROV transect 5 from JC060. The vehicle was deployed
at 16:29z.
Wednesday 18 September 2019
Mostly sunny with light winds, force 3. Sea state slight to moderate, 3‐4
HyBIS continued its operation smoothly till it had to be recovered, and was back on deck by 03:03z.
The ship then moved back to the Eastern Darwin Mounds for a couple of boxcores (DY108‐028‐BC14
and DY108‐029‐BC15), before the AUV would be launched. The core was deployed at 04:35z and backon deck at 05:40z, before being redeployed at 06:12z and being back on deck by 07:10z.

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Then it was time for the next Autosub mission (DY108‐030‐AUV153). With an uncertain weather
forecast, and the assessment that the last two recoveries had been borderline, it was decided tocollect the most important dataset first. Given the good results with the BioCAM the day before,
another BioCAM dense grid was planned, this time over the Eastern Darwin Mounds. The vehicle wasin the water by 09:01z, and travelled as planned to the seabed. During the descent, it was tracked
successfully using both the USBL and Tracklink systems. However, once at the bottom, the Tracklink
once again lost communications. By that time Autosub had drifted over 400m to the NNW of theforeseen starting waypoint. In an attempt to restore communications, the ship was manoeuvred rightover the vehicle, and all shipboard acoustic systems were switched off. Eventually also the power
setting on the Tracklink was increased, and a message could be sent to the AUV, which was received
just in time for it to make it to the waypoint before the waiting time‐out. We followed the system fora while with the USBL to check it was following the correct path, and kept recording USBL positions
for the duration of the subsequent boxcoring operations. Two more boxcores were taken in the
Eastern Darwin Mounds (DY108‐031‐BC16 and DY108‐032‐BC17), with the operations starting at
12:07z and finishing at ca. 15:00z. We then re‐positioned for the HyBIS dive of the night (DY108‐033‐
HyBIS56), which was repeating JC060 ROV dive 25. The system was in the water at 16:17z, and apartfrom the video surveying of the seafloor habitats, it also carried out an inspection of the second
marker buoy left in the Eastern Darwin Mound area. Unfortunately some of the video recordings failed
or became corrupted, and only the Scorpio stills of the marker bouy were saved.
Thursday 19 September 2019
Overcast with light to moderate winds, force 4, sea state slight, 3.
HyBIS came on deck at 03:04z, allowing the ship to reposition for the first boxcore of the day (DY108‐
034‐BC18). On the way, we picked up USBL signals from Autosub again, providing more tie‐points forthe navigation corrections that the BioCAM team apply to their data. The boxcore was deployed at
04:17z and recovered at 05:21z. The ETA for Autosub was 07:00z, but given the previous experience,no further boxcoring was planned before the AUV recovery, to allow good navigation data to becollected before recovery. However, this time Autosub took a little longer than planned, and it only
came to the surface around 08:30z. It was captured by 09:25z, and on deck by 09:35z. Again it hadcollected a full BioCAM dataset.
With these data on board, we set off for the Western Darwin Mounds again, in order to complete theboxcore series there. At 11:15z, the first core was deployed (DY108‐035‐BC19), but it came on deck at
12:19z with only a small sample from one of the mounds. A second core (DY108‐036‐BC20) was
deployed in a tail at 13:32z, and brought a good core on deck at 14:29z. It was decided that there was
too little time after that to take any further cores before the HyBIS dive of the night, so the ship slowly
made its way to the start point of the HyBIS dive (DY108‐037‐HyBIS57). There we had to wait until the
HyBIS team were on shift (16:00z) before deploying. By 16:25z the system was in the water, foranother dive in the Western Darwin Mounds. We repeated part of the JC060 ROV06 transect, but also
spent some time in an attempt to find the whale fall that the BioCAM team had found in their dataset.
Unfortunately their navigation correction calculations were still running, and there was someuncertainty about the position of the whale fall. We checked out several positions, also using thescanning sonar on HyBIS, but could not find the carcass. Towards the end of the dive some new
mounds were inspected, at the same time providing imagery for cross‐correlation with the BioCAM
data.
Friday 20 September 2019
Sunny weather with light to moderate winds, force 5. Sea state slight to moderate, 3‐4.

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HyBIS was back on deck at 02:46z. We then repositioned to the last mound boxcore site in the Western
Darwin Mounds to try once again to obtain a good core there (DY108‐038‐BC21). The core was
deployed at 04:07, and back on deck at 05:07, but again did not provide a full sample. It was sieved
and stored nonetheless.
The next operation was an Autosub deployment over the Eastern Darwin Mounds, in order to re‐survey the area with high‐resolution sidescan sonar, but during the pre‐dive checks no wifi
communication with the vehicle could be established. The error required more investigation, and aftersome debate the mission was delayed till the afternoon. Instead we moved back to one of the mounds
that was boxcored before, to try to obtain a megacore there for meiofauna studies. Three attempts
were made (DY108‐039‐MC01, DY108‐040‐MC02 and DY108‐041‐M03), but none of them weresuccessful. The second deployment did bring up some fossil coral fragments which were bagged andstored for dating. The coring operations lasted from 09:01z till 12:55z. By that time the error on
Autosub had been isolated, investigated and repaired, and the ship moved back to the AUV start
position.
However, during the pre‐dive checks before the mission, it was established that the batteries had
emptied a little too much to allow a 24h mission, so an hour was spent on re‐charging. After that, it
became clear that the Iridium beacon did not respond. The spare beacon was mounted, but did not
respond either, so this issue had to be resolved before the AUV could be deployed. This took aconsiderable amount of time, but eventually the spare beacon did activate, and the mission wasscheduled (DY108‐042‐AUV154). Autosub was deployed at 16:20z, but then had a fault on the Phins
IMU. This is a vital part of the control system, so the mission was cancelled and Autosub was broughtback on board at 17:02z. After this we gave up on further AUV deployments for the day: the AUV teamwas fully out of hours and the real cause for the errors had not yet been established, so it was decided
to analyse the problem in the morning and attempt a mission around lunchtime.
We then moved to the HyBIS site for the evening (DY108‐043‐HyBIS58): the repeat of a WASP video
transect from 1999, over a small ‘pocket’ of mounds north of the main Eastern Darwin Mounds. In
1999, quite a lot of live coral had been found there, and we wanted to check if any of it had survived.
HyBIS was deployed at 18:00z, and upon arrival at the seafloor at 18:32z we immediately found an
extensive patch of live coral. Along the dive large patches with large colonies of live Lophelia andMadrepora were found, together with a diverse associated community and the inevitable marine
litter. The video transect also passed over several barchans dunes.
Saturday 21 September 2019
Sunny with light to moderate winds, force 4. Sea state slight to moderate, 4 coming down to 3.
As always, HyBIS came back on deck at 02:50z. From there, we started a dedicated multibeam survey
with the EM122 multibeam system (DY108‐044_MBES01), mapping the wider N Rockall Trough over& around the Western & Eastern Darwin Mound provinces. Multibeam data were collected duringJC060, but they were collected under adverse weather conditions, and were of poor quality. The
survey continued until 13:30z, after which we went full speed to the start point of the AUV mission(DY108‐045‐AUV155). We had monitored the system all morning to detect the cause of the problem
with the Phins IMU, however the fault had not re‐occurred. It was then decided to deploy Autosub
but keep watch over her for the whole mission. Autosub went through its pre‐dive checks successfully,
and was deployed at 15:13z for a sidescan sonar mission over the Eastern Darwin Mounds. We
followed the track with the ship through the night.

Sunday 22 September 2019
Sunny, calm weather with light to moderate winds, force 4. Sea state slight, 3.
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Autosub performed well throughout the night, but the monitoring continued for the rest of themission, and this did pay off, because when the vehicle finished the sidescan sonar part of the mission(14:05z), it started to behave erratically. The AUV team was alerted, and the vehicle was followed on
the USBL system as it started to come to the surface. As soon as it surfaced, the ship was put in position
for recovery, and the AUV was back on board at 15:33z. Investigations later showed that the vehicle
had made contact with the seabed, before the collision avoidance system dictated it to come up. The
fault was due to an error in the ADCP and the loss of bottom lock.
With the AUV on board, the vessel repositioned for a HyBIS dive in the Western Darwin Mounds(DY108‐046‐HyBIS59). This dive finished off the repeat of JC060 dive ROV06, and added theinvestigation of some new mounds that were the target of the AUV mission. HyBIS was deployed at
16:58z and carried out its dive smoothly for the rest of the night.
Monday 23 September 2019
Overcast with low clouds, dense fog in the afternoon and heavy rain showers in the evening. Moderate
winds, force 4‐5, sea state slight, 4 calming down to 3.
HyBIS was recovered at 02:16z, and the ship was slowly repositioned to the chosen location for the
deployment of a short mooring. Before the mooring package went into the water, a calibration CTD
was carried out (DY108‐047‐CTD06). The instrument was in the water at 05:02z and back on deck at
06:20z. Apart from the typical CTD package, the frame also carried three microcat CTDs (of which twowould be chosen for the mooring), a USBL beacon from the BioCAM team, and a large number ofpolystyrene cups to be shrunk under pressure. Once back on deck, the microcat CTDs were checked,
and the two systems with most robust values were chosen for the mooring (DY108‐048‐MR01). They
were quickly attached to the mooring string, and the deployment operation started at 07:36z with the
deployment of the floatation. By 08:01z the anchor was lifted over the side and the mooring string
sank to the seabed. We carried out a triangulation operation to confirm the exact deployment
position, which finished at 09:50z. From there we had planned a multibeam survey (DY108‐049‐
MBES02), but it took the ship an hour to get going, mainly because of a miscommunication with the
ship’s engineering team carrying out maintenance tasks. Eventually, at 10:48z, the survey started, but
it could only last till 12:30z, as we had scheduled the next AUV deployment at that time. The AUVteam had been busy working on the ADCP problem from the night before, but eventually it was adense fog that made us delay the Autosub deployment with another day. As alternative programme
we deployed the megacore twice on a mound in the Western Darwin Mounds (DY108‐050‐MC04 andDY108‐051‐MC05), starting at 13:33z and finishing at 15:47z, but neither of the deployments weresuccessful. It appeared that also the mounds in the Western Darwin Mounds are too hard to core.
With the corer back on deck, the ship went on transit to the Eastern Darwin Mounds for the last HyBIS
dive there (DY108‐052‐HyBIS60), repeating JC060 tracks ROV02 and 03, and exploring an area with an
unusual signature on the sidescan sonar maps.
Tuesday 24 September 2019
Slightly overcast, with sunny spells and moderate winds, force 4, occasionally 5. Sea state slight tomoderate, 3 to 4
HyBIS came on board at 02:35z, after which we started another multibeam survey (DY108‐053‐
MBES03). The ship started the transit at 03:03z, and started the actual survey at 03:55z. We continued
surveying until 11:31z, when we had to return to the Western Darwin Mounds for the next AUV
deployment (DY108‐054‐AUV156). We arrived on station at 12:27z.
In the meantime Autosub had been fitted with the spare ADCP system, and all checks on deck had
been completed successfully. The system was deployed at 13:36z; the mission started with a test run
for the new ADCP. The vehicle was programmed to surface again to allow data download, and it was
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spotted at 15:04z. It started diving again at 15:25z, this time for the real science mission, anotherdense grid with BioCAM covering part of the Western Darwin Mounds. When it reached the seafloor,
an updated start position was transmitted to the vehicle. However, the positional offsets were notestimated correctly, and another correction had to be sent. Unfortunately, the vehicle failed to pickup this second command, even after several attempts. Eventually the waiting pattern timed out, andthe mission was carried out with an offset of ca. 65 m to the south.
We continued to track the vehicle for a while at the seabed, before setting of for the last HyBIS divein the Darwin Mound area. Communications through the Tracklink system continued, and seemed toindicate that the BioCAM system may not have recorded any photographs. However, by the time thiswas established, a dense fog had come up again, and it was decided to leave the AUV doing the
programmed mission, hoping that the error sat with the Tracklink communication rather than with
the BioCAM.
Eventually (at ~18:15z) we slowly moved to the start position of the HyBIS dive (DY108‐055‐HyBIS61).
The vehicle was deployed at 19:32z, and reached the seabed at 20:06z. An error in the georeferencingof the OFOP underlay map meant that the planned track was not followed for the first hour, however,as this was an exploratory dive, no essential data was lost. Corrections were made in time to enable
the rest of the dive to take place along the planned line.
Wednesday 25 September 2019
Overcast with moderate to strong winds, force 5, occasionally 7. Increasing sea state, 4.
HyBIS was brought on deck by 02:39z, after which the ship was scheduled to check on the Autosub’s
USBL position. A miscommunication regarding the waypoint at which this check had to happen
resulted in an hour’s delay, but eventually Autosub was found in the area where it was supposed tobe, and the USBL positions confirmed it was working along the correct track. At 05:02z, we thenstarted another multibeam survey with the EM122 (DY108‐056‐MBES04), mapping the south‐easternpart of the MPA. The weather was deteriorating, though, and the data quality was less than the day
before. We finished the survey at 13:28z and transferred to the end‐point of the AUV mission.
Although the ETA for the vehicle at the surface was 15:30, by the time we arrived at the waypoint(~14:30z), Autosub was already on its way up. It reached the surface at 14:44z, and was recovered ondeck by 15:54z. Unfortunately it very quickly became apparent that the BioCAM had not collected any
photographs. Further investigation the next day revealed that one of the cables connecting BioCAM
with the main Autosub system must have failed under pressure during the second descent. The system
did come back online during the ascent, but the break in communication meant that the BioCAM did
not receive the ‘start’ command, and hence did not record any images.
Unfortunately, our time in the Darwin Mound area was up, so we went on transit back to the landersite as soon as Autosub was secured on deck. The aim was to carry out the HyBIS dive that we hadplanned at the start of the cruise, but that had been cut short because of a problem with the vehicle.
Thursday 26 September 2019Partly cloudy with light to moderate winds, force 4. Sea state calming down to 3.
While the sea state had come down throughout the night, the ship did encounter some strong
currents, and a speed of 10kn could not be maintained for most of the transit. Problems with theAutopilot system on the bridge (which had affected the ship from the start of the cruise) also meant
the ship slowed down below optimal speed. Hence our arrival at the OSNAP ADCP lander site wasdelayed by 3 hours. Still, by 13:45z HyBIS was deployed (DY108‐057‐HyBIS62) for the investigation of
the SAMS ADCP lander. The vehicle was at the seabed by 14:28z, and within 15 mins the lander was
found, thanks to the forward scanning sonar. The frame was completely silted over, the dome thatwas to protect the ADCP was ripped off and the ADCP and gimbal system were pulled out of the frame.
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Trawlmarks all around, visible on the forward looking sonar, showed the most likely cause of thisdestruction. We used HyBIS to collect detailed visual evidence, and discussed potential ways ofrecovery. However, after evaluation, it was decided that there was too much risk and not enough time
to attempt a recovery of the system with HyBIS. Hence the position of the lander was recorded, andthen HyBIS was brought on deck by 15:42z, so we could continue the transit to the BLT CTD sites.
Friday 27 September 2019Partly cloudy, good visibility, moderate to strong winds, force 5. Sea state moderate, 4.
The transit continued at an average speed of 8.4kn. We arrived at the first BLT CTD site (DY108‐058‐
CTD07_27), ~1800 m depth inside the submarine canyon, at ~15:30z. The CTD was deployed at 15:50z,
and was lowered and raised repeatedly in a continuous operation for 24h.
Saturday 28 September 2019Partly cloudy, calm weather, light to moderate winds, force 4. Sea state slight, 3.
We continued the 24h CTD work until 16:39z. Around 08:00z the altimeter of the CTD showed someerrors, and some of the CTDs were not lowered as close to the seabed as others (target altitude was~5‐7m). However, after two more cycles the altimeter partly recovered, and the work could becontinued as normal.
Once on deck, the CTD was serviced (altimeter swopped out, LADCP data downloaded and battery
pack swopped out). The data download took much longer than anticipated, so the start of the second
24h CTD (DY108‐059‐CTD28‐34) was delayed until 20:18z. This 24h yoyo cast targeted the canyon rim,
at ca. 1400m water depth.
Sunday 29 September 2019Partly cloudy with occasional showers, light to moderate winds calming down from force 4 to force 2.
Sea state slight, 2‐3.
CTD work continued throughout the night. However, at 03:43z the CTD unexpectedly made contact
with the seabed. It appeared that too much cable had been paid out, because the winch system did
not stop automatically at the requested length of wire out. An estimated 15m of wire was depositedon the seafloor. It was carefully winched back up, followed by the CTD itself, and the whole system
was brought on deck at 04:24z. All components of the CTD and winch were inspected thoroughly, butluckily no major damage had occurred, and it was decided to deploy the system again for the rest of
the 24h slot (DY108‐060‐CTD35‐48). The instrument was back in the water at 05:26z, and continued
its operation until 19:52z, when it was brought back on deck.
With that, we finished science operations, and once the equipment was safely secured on deck, theship set sail to Southampton.
Monday 30 September 2019
Overcast with regular rain showers, strong winds up to force 8. Sea state moderate, 4.
As the transit continued, the science and technical teams started to pack up the equipment, and wrote
the necessary sections for this cruise report. Data was backed up and initial analyses completed.
Tuesday 1 October 2019Partly cloudy with occasional showers. Strong winds easing, force 7 to 5. Sea state moderate to rough,4‐5.
Clocks went forward to GMT overnight, while the transit continued. The ship made good speed, andthe rest of the transit progressed well.

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Wednesday 2 October 2019Partly cloudy with occasional showers. Winds had eased, and sea state as well
The transit continued as before, and we picked up the pilot at the agreed time (12:30 BST). We dockedin Empress Dock at 14:15 BST, and started the demob immediately.

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6. METHODS AND INITIAL RESULTS
6.1. Acoustic mapping & profiling (Tim Le Bas, Catherine Wardell)
6.1.1. Shipboard Multibeam Systems: EM122 and EM710
RRS Discovery has two multibeam echosounders, a Kongsberg EM122 (12kHz) and a Kongsberg EM710(70kHz). Both the systems are hull mounted. Before these systems were started, 1 hour of cetacean
watch was done from the vantage point of the bridge, and at no time in that hour were cetaceansobserved. The system was then started. Sound Velocity profiles were calculated from CTD profiles
and entered into the systems. Most of the cruise was in deep water (>200m) and thus the EM122 wasused more frequently. The EM710 was used for times in shallow water such as The Solent (during
passage) and The Minch (when sheltering from bad weather).
The EM122 was set to DEEP and to have equidistant sampling. Some depth filters were applied duringacquisition as the system often lost lock on the seafloor signal without this. The offsets, lever arms
and calibration values, listed in Figs. 7.38 & 7.39 were already inserted into the acquisition system(SIS) from the previous trials cruise DY107.
Processing of the bathymetry data was done using CARIS HIPS and SIPS v9.1 and using a vessel file ofzero offsets and no attitude corrections. A "Polpred" correction tide file was applied for the EM122
data, though being a deep water system it was assumed 1% depth errors were considerably higher
than tidal range of 1.5m. The data were quite noisy but easily edited by the swath and subset editors.
Bad weather did affect the data quality and at times made the data unusable.

Fig. 6.1 ‐ Tidal data for Darwin Mounds area for period of multibeam data collection
In the region of the Darwin mounds 4 dedicated periods of time were given to EM122 multibeam
survey (Table 6.1) and added to some transit lines between waypoints for a near full coverage map.

Table 6.1 – Dedicated multibeam surveys in the Darwin Mounds area
1
2
3
4Multibeam Start
2019‐09‐21 03:29:10
2019‐09‐23 10:48:33
2019‐09‐24 03:02:36
2019‐09‐25 05:01:41

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Multibeam End
2019‐09‐21 13:38:21
2019‐09‐23 12:29:52
2019‐09‐24 12:12:53
2019‐09‐25 17:44:09
Total

Duration (hours)
10:09:11
01:41:19
09:10:17
12:42:28
33:43:15

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Bathymetry grids were made at 100m, 50m and 25m resolution using the CUBE method (IHO S44
Order 2 and using Density and locale). A small amount of interpolation was required to fill small gaps
due to poor data, caused by weather. The mounds themselves were not visible on the bathymetry
map due to their minimal height in comparison with the error in multibeam depth. Vertical error was
estimated to be 5‐10 metres (1%).

Fig. 6.2 ‐ Darwin Mounds area bathymetry and ship tracklines used for data acquisition.

Multibeam backscatter processing was done in FMGT v7.8.3 Build 1022. As the ship was leaving
Southampton the system recorded data very near to the backscatter calibration patch of western
Solent (Roche et al., 2018).
Table 6.2 Calibrated backscatter values for the seafloor calibration patch in the W Solent
FMGT processing
Discovery EM122
Discovery EM710
Calibration Value (Belgica
MBES system)

Mean
Backscatter‐26.9dB‐15.3dB‐16.3dB

Standard Deviationof Backscatter
3.5dB
2.7dB
1.8dB

Frequency
kHz
12
70
300

In the area of the Darwin Mounds the EM122 multibeam data was also processed in FMGT to a
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the hull. The resulting mosaic was of poor quality but did seem, in places, to show some correlation
with the mound features. The data was attempted to be put through the PRISM software for more
controlled processing, but it was found that data format (.all) was not compatible with the "Replay"procedure previously used and so could not be read.

Fig. 6.3 ‐ Backscatter mosaic for Darwin Mounds area. Pixel resolution was 5m

6.1.2. Shipboard SBP System
RRS Discovery has a Sub‐Bottom Profiling system as part of the EM122. The system was usedperiodically. We recorded 148 raw files and converted in 216 segy automatically. No further
processing was carried out on the SBP data.

6.1.3. Autosub 6000 Sidescan
The Autosub 6000 system had two dedicated sidescan missions (Table 6.3).
Table 6.3 Overview of the Autosub6000 sidescan sonar missions

M151
M155

Data Start

Data End

Thu Sep 12
15:44:45
Sat Sep 21
16:33:53

Fri Sep 13
09:01:00
Sun Sep 22
14:02:41

Height(Altitude)

Line
Spacing

15m

200m

15m

180m

Area nameWest Darwin
MoundsEast Darwin
MoundsRange
setting

Total
Length300m

68.5km150m

88.4kmProcessing of the sidescan imagery was approached in two ways (compare Fig. 6.4):


SonarWiz (v7.0)
PRISM (v4.0)

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Sonarwiz processing
Initially the JSF files were imported into SonarWiz but it was discovered that some of the files had gaps
or had missing data, and thus these files were put through the SalvageCorruptZeroes.exe program.
The first file however had a channel count of 0 (instead of 2) and still could not be read.
Conversion to XTF format can be done in three ways:
1. Discover.exe, the EdgeTech data replay software. This has the advantages that the user cansee each file's imagery on the screen as it is converted but it is slow due to each file having to
be loaded individually one by one.
2. JSF2XTF.exe This has an advantage that it can do all the files in a single command.
3. JSFFileConverter.exe This is similar to JSF2XTF.exe as it has no graphical output but is time‐
consuming due to each file having to be loaded individually by the user one by one, but isquicker than Discover.exe
The files had the Autosub6000 navigation embedded, of where the system thought it was located. If
a better navigation file was available the data could be updated using NavInjectorPro .exe (V6, partof the SonarWiz capability).
The import facility in SonarWiz will take both JSF and XTF formatted data but as some data would not
be imported in JSF format, XTF format imports were used. A UTM zone of 29N was chosen. Advanced
settings options for XTF format were: Turn off Min‐Max Amplitude, and using 4096 samples.
When imported into SonarWiz the first task is to calculate the slant‐range correction and use Bottom
Tracking. The Bottom Track variables were: Blanking 1 Duration 20 Threshold 5, Port Sync, Port andStarboard. Next an EGN (Empirical Gain Normalisation) was built using all files and then applied to thefirst file. Range was reduced to 120m on both sides and then using the file manager used to make all
the other files to be like the first file.
Initially the polarity of the output is white is low backscatter and black is high backscatter. The viewing
setting of data overlap were Root Mean Square and drawing mode High resolution. Export of themosaic is suggested to be done on the standard output as a project Geo‐image in 8 bit Erdas Imagine
format. Output resolution was chosen to be 0.2m. On import to ArcGIS the polarity of the imagery
was reversed so that weak backscatter was dark and strong backscatter was light.
The resulting mosaics are likely to be misplaced due to an incorrect start location but this wascorrected by using georeferencing of the new mosaic to the 2011 mosaics which had themselves beengeoreferenced to match the ROV interpretation from previous cruises.
PRISM processing
High frequency (410kHz) sidescan data was downloaded from the Autosub disks in the .jsf format.
These .jsf files were converted into XTF format using the Edgetech Discover 4200 MP 2.03 software;
this allowed viewing of the data during conversion. Any files not converted successfully were repairedin SalvageCorruptZeroes.exe software. The settings for replay were set at High Freq: Gain 30dB andTVG 11dB/100m. The XTF format files were then converted into PRISM format (.cdf) using the
program reson2prism.
As listed in Table 6.3, two Autosub dives were undertaken collecting sidescan sonar data. For diveM151 the range of the sonar was set to 300m whilst for dive M155 the range was 150m. Due to thisvariance the data from each dive was treated slightly differently. For both dives the data was averaged
and subsampled by a factor of 5. For dive M151 the data files were given 3000 samples per side whilst
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for dive M155 2500 samples per side were used. The PRISM commands.cfg file contained the following
commands:
mrgnav_inertia ‐i %1 ‐o %0 ‐u 0 ‐r 0.0,0.0 ‐n navfile.veh_nav
widealt ‐i %1 ‐o %0 ‐p
tobslr ‐i %1 ‐o %0 ‐r0.0576 , res # high freq 110m 6 Hz subsamp 5
edge16 ‐i %1 ‐o %0 ‐m
shade_tobi ‐i %1 ‐o %0 ‐n 1000
filter ‐i %1 ‐o %0 ‐b 1,351 ‐h ‐v 1,5000
filter ‐i %2 ‐o %0 ‐b 21,351 ‐l ‐v 1,5000
wtcombo ‐i %2 , %1 ‐o %0 ‐c 1,1
restorehdr_tobi ‐i %1 ‐h %5widealt ‐i %2 ‐o %0 ‐h ‐l 500

Bottom tracking was conducted in PRISM, setting the water column threshold and starting altitude ofeach file. This was viewed and checked before the navigation was imported from corrected BioCam
navigation for dive M151 or extracted from the .cdf files which contain the embedded Autosubnavigation for dive M155. A map was created fitting the survey boundaries using the mapcreatefunction in PRISM. The function prismrange was then used to insert the data and navigation into thismap at a resolution of 0.2m. The final map was viewed in ArcMap to check for navigational
consistencies and data quality. Due to an incorrect start position the final mosaic is likely incorrectly
positioned and so pre‐existing data was used to georeference this.

6.1.4. Autosub 6000 SBP
The sub bottom profiler data was collected using the Edgetech 4200 mounted on Autosub 6000 fordives M151 and M155 only. The system was set to 2‐16kHz with a 16ms sweep, and was used at analtitude of 15m.
Preliminary data processing was conducted in order to visualise the profiles. The Edgetech software
collects the SBP data in .jsf format, this was converted to .sgy format using the programme jsf2segy ina Linux environment. I
nput: Edgetech .jsf file, output (‐o) .sgy file, options used: ‐a use the analytic (correlated) sub bottom
data rather than the raw data.
The SeisUnix command was then used to visualise the data:
segyread tape=input file.sgy endian=0 | segyclean | sugain epow=5 | sushift tmin=0 tmax=0.3 |supsimage perc=98 > output file.ps
The data was also input into the SonarWiz software. The software allows easy viewing of the sub‐bottom profiler data when doing bottom tracking (Figs. 6.5 & 6.6). Once returned to shore alternative
software will be used to input the corrected navigation and Autosub altitude to the SBP data.

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2019 M151
SonarWiz
Processed
2011 M40
PRISM
Processed

20cm SonarWiz

20cm PRISM

Fig. 6.4 Comparison of 2011 and 2019 Autosub6000 EdgeTech sidescan sonar data, processed using different software systems.PRISM provides sharper results
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Fig. 6.5 ‐ Sub‐bottom profile from East Darwin Mounds area showing a mound. Note the remnant
horizontal horizon in line with the seabed under the mound.

Fig. 6.6 ‐ Sub‐bottom profile from East Darwin Mounds area showing a strong reflector about 2m below
the seabed surface.

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6.2. BioCAM‐based mapping (Blair Thornton, Adrian Bodenmann, Miquel Massot, Jose
Cappelletto, Takaki Yamada, David Stanley)6.2.1. Description of the device
6.2.1.1. BioCam
BioCam (see specification Table 6.4) is a visual mapping system that collects data for generating 3D
reconstructions of the seafloor along the trajectory of an underwater vehicle. The device consists of astereo camera and logging unit, two line lasers, two LED strobes and two strobe driver bottles. The
laser, strobes and cameras are mounted downward looking with an unobstructed view to the seafloor
from an altitude of between 4 to 10 meters. A reed switch and a magnet are used for arming the sheet
lasers.
Table 6.4: BioCam specifications

Mass

39.6 kg (in air)
17.2 kg (in water)Power

48 V, 0.8 A (typ.) 1.5 A (peak)

Depth rating

3000 m

Mapping altitude

4 to 10 m

Maximum surge velocity@6m

1.5 m/sBaseline between camera and laser/strobe Ideal: 1.5 to 2.0 m (Minimum: 1.0 m)
Swath at 6m

Swath: 8.4 m

Resolution at 6m

3 mm/pixel

Laser wavelength and power

525 nm, 1 W (class 4)

Laser safety switch

Magnetic reed switch

6.2.1.2. Integration on Autosub6000
BioCam was integrated to the underside of Autosub6000 as shown in Fig. 6.7 using a bespoke mounting
setup (designed by Richard Austin‐Berry, MARS). There is one strobe at the front and one at the backof the vehicle in order to evenly illuminate the images that the camera pair in the main housing
acquire. There is a sheet laser at the front and one at the back, with the laser line aligned perpendicular
to the direction of motion. A reed switch at the end of a cable is mounted on top of Autosub6000 anda magnet is installed next to it. The reed switch interrupts the power supply to the lasers when themagnet is removed. The magnet is attached to the recovery line, so that the magnet is separated fromthe reed switch during recovery (designed by Owain Shepperd, MARS). While the laser is normally also
disabled through a software watchdog before recovery, this adds an additional layer of safety toguarantee that the laser is turned off during recovery of the AUV.

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BioCam is connected to Autosub6000 via a power and Ethernet cable through which Autosub6000
sends the commands for starting and stopping of the data acquisition (command interface
implemented Rachel Marlow, MARS). BioCam also sends information including in which dataacquisition mode it currently is and how many images have been collected to Autosub6000, which
forwards that information via the acoustic modem to the ship (health status monitoring interface
developed by Adrian Bodenmann, UoS).

Fig. 6.7 BioCam components mounted on Autosub6000

6.2.2. Method to collect data
6.2.2.1. Settings for BioCam
The typical dive phases for a BioCam and Autosub6000 mapping survey are shown in Fig. 6.8.

Fig. 6.8: Typical mission phases for BioCam mounted on Autosub6000.

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These operations consist of the following sequences:






Dive: the AUV dives nose‐down to a target altitude.
Laser calibration: during the last portion of descent, both cameras and lasers are triggered togather imagery at varying depths for a posterior laser plane calibration.
Mapping: the main portion of the dive is a waypoint following mission at a controlled speed
and altitude, gathering strobed and laser images.
Surface: the AUV comes back to the surface and BioCam stops collecting images.
Data extraction: once the AUV is on deck, BioCam is connected to the ship network to
download its data on a network storage.

The parameters for BioCam / Autosub6000 missions are summarized in Table 6.5.

Table 6.5: Mission parameters for BioCam and Autosub6000
AUV speed
AUV altitude
Strobe frequency
Strobe duration
Laser frequency (mapping)
Laser Frequency (laser calibration)
Laser duration
Camera shutter speed

1 m/s
5 to 6 m
0.3 Hz
7 ms
10 Hz
2 Hz
7 ms
10 ms

6.2.2.2. Workflow
Raw images of laser line profiles and colour stereo imagery of the seafloor are captured together withnavigation data from the AUV’s DVL (velocity), IMU (attitude) and pressure (depth) sensors and USBL
measurements of position from the vessel. The information is fused to extract colour and shapeinformation about the seafloor and generate dimensionally accurate 3d reconstructions (Fig. 6.9).
Prior to mapping, the raw information collected are corrected for measurement artefacts. The raw
imagery is corrected for the wavelength dependent attenuation of light through water and uneven
distribution of light from the strobes. The dead‐reckoned navigational data of the AUV suffers fromunbounded error drift as velocity measurements are integrated to estimate position. To overcome
this, the information is fused together with the USBL position fixes, which have a high level of
uncertainty but their uncertainty is bounded.

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Fig. 6.9 Processing workflow after data collection. The images are colour corrected and the navigation
fused to feed a mapping pipeline.

6.2.2.3. Data processing
Correction of colour
The parameters of a physics‐based model of light attenuation with distance, as measured by thealtitude readings of the DVL, are estimated using a regression across the different colour channels
measured by BioCam. This is carried out for every pixel in the imagery for each of the dives, since
water quality, which affects these parameters, is expected to vary between dives. Using this model,
colour data that would be observed without the presence of the water is estimated. To compensate
for wide‐angle lenses introducing vignette effects (darkening of the edges) and unevenly lit scenes, agrey‐world assumption is imposed for each pixel across the entire dataset. This allows evenly lit scenes
with the correct relative colour balance to be generated (Fig. 6.10). Camera calibrations are also
applied to undistort images, though the distortion with the domed pressure windows used on
BioCam’s cameras is relatively small, even before applying the calibration.

Fig. 6.10 Example images from the correct colour process.

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Correction of navigation
Raw navigation data of internal sensor readings and USBL readings are fused using an Extended
Kalman Filter to generate more accurate navigation estimates (Fig. 6.11). This takes into account theposition and orientation probability distribution of the vehicle based on the measurement updates.
This navigation solution gives position estimates for when each raw image was captured.

Fig. 6.11 Example data from the correct navigation process.

Laser mapping pipeline
The algorithm described in Bodenmann et al. (2017) is used to generate texture‐mapped 3D
reconstructions based on images of the laser line profiles and the strobed colour images of theseafloor (Fig. 6.12). Images of laser lines and their respective vehicle poses are processed to extract
depth information of the seabed at high lateral and vertical resolution, which is used to form a dense
point cloud of the seabed’s bathymetry from which a 3D mesh is then produced. Colour data and its
associated vehicle poses are combined with the mesh to produce fully 3D, coloured, visual maps ofthe seabed.

Fig. 6.12 Example images from the mapping pipeline.

On one of the first dives, the system was calibrated to obtain the laser plane equations with respect
to BioCam. The calibration procedure consists of acquiring stereo images of the laser line projection
from different altitudes. The laser lines are detected in both camera images and triangulated to form
two point clouds, one for each laser. Fig. 6.13 shows the point clouds corresponding to the two laser
planes. Using a least squares algorithm, the plane equations that best fit the point clouds are
determined. The laser plane equations determined based on the data collected during Autosub6000
dive M151 are
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0.5138𝑥

0.007583𝑦
00.010614𝑧

0.85780.5546𝑥0.023958𝑦
00.007533𝑧

0.8317

Fig. 6.13 Results of laser plane calibration. The two laser planes have been correctly detected and its
3D points shown with respect to BioCam coordinate frame.
Stereo mapping pipeline
The algorithm described in Johnson‐Roberson et al. (2010) is used to build texture‐mapped 3D
reconstructions based on strobed stereo pairs. Stereo matches between the images of a stereo pair asshown in Fig. 6.14 are used to generate a 3D reconstruction of the scene. Matches between images ofoverlapping transects are also used in a SLAM algorithm to improve the navigation solution. Finally, all
the points are aggregated into a texture‐mapped 3D model of the entire mapped area.

Figure 6.14 Matches detected in a stereo pair of a whale fall

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6.2.3. Autosub6000 dives with BioCam
M150: System tests diveA 2‐hour system test was performed at Mingulay reef to confirm manoeuvrability of Autosub6000
with BioCam as it was the first time this setup has been used, and to confirm that there was nointerference between BioCam and the side scan sonar.

Table 6.6 M150 dive data

Site

Mingulay Reef

Mission

M150

Ship (deploy/recovery)

In waterOn deck

Date / Time

10/09/2019

06:41:00

10/09/2019

10:27:00

Coordinates (LAT/LON)

56°47.995 N

7°24.839 W‐‐

BioCam (mapping)Start

Date / Time

10/09/2019

07:11:09

10/09/2019

09:33:28

Coordinates (LAT/LON)

56°48.0749 N

7°24.6848 W

56°48.2166 N

7°25.0130 W

Water depth

206 m

End

210 m

Fig. 6.15 Trajectory for dive M150

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Fig. 6.16 Depth profile for dive M150

M151: Calibration dive
Calibration data was collected following a side scan survey mission at the WDM. The dive consisted instereo imagery collection of the dual laser line projections from altitudes between 10 to 5 m todetermine the precise position and orientation of the laser planes. After this, a mapping test was
performed to determine the optimal altitude for data collection. The dual laser planes determinedfrom this dive are used in subsequent data analysis when generating laser bathymetry, and theillumination levels indicated that an altitude of 5 m would be most suitable for future dives.

Table 6.7 M151 dive data

Site

Darwin Mounds (West)

Mission

Ship (deploy/recovery)

In waterOn deck

Date / Time

12/09/2019

13:08:00

13/09/2019

16:29:00

Coordinates (LAT/LON)

59°48.772 N

7°20.0495 W

59°46.6958 N

7°18.3166 W

BioCam (mapping)Start

Date / Time

13/09/2019

10:13:48

13/09/2019

11:15:34

Coordinates (LAT/LON)

59°49.0020 N

7°22.2424 W

59°48.9932 N

7°22.2190 W

Water depth

989 m

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M151

End

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Fig. 6.17 Trajectory for dive M151

Fig. 6.18 Depth profile for dive M151
M152: Dense grid survey
A 24 h survey was carried out to generate dense grid imagery of a 900 m by 320 m area (29 hectares)in the WDM, covering a total distance of 75.9 km. The survey transects consisted of 80 x 900 m longnorth‐south transects at 4 m spacing mapped from 5 m altitude with 2 cross track lines to improvenavigational estimates using visual slam. The waypoints generated followed a modified Zamboni
pattern so that the minimum turning circle diameter was set to 32 m, and the vehicle forward velocity
was set to 1.2 m/s. Altitude tracking was performed using the altitude range of the Autosub6000’s
ADCP and the obstacle avoidance sonar on Autosub6000 was not used.
M152 Preliminary outputs
The dive succeeded in collecting millimetre resolution 3D imagery of the targeted region. Data consistsof 20,663 strobe illuminated stereo pairs and 605,118 dual laser bathymetry images. A whale carcass
was also discovered in the north west corner of the mapped area.

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In terms of vehicle performance, the vehicle had difficulties maintaining altitude over the mounds
using only its ADCP range. Fluctuations in vehicle velocity are also observed due to bottom currents.
The high quality of imagery obtained led to a decision that images could be taken from 6 m altitude in
future dives.

Table 6.8 M152 dive data

Site

Darwin Mounds (West)

Mission

M152

Ship (deploy/recovery)

In waterOn deck

Date / Time

16/09/2019

06:39:00

17/09/2019

06:15:00

Coordinates (LAT/LON)

59°48.8725 N

7°21.2556 W

59°48.0975 N

7°21.3423 W

BioCam (mapping)Start

Date / Time

16/09/2019

09:05:07

17/09/2019

02:51:52

Coordinates (LAT/LON)

59°48.8420 N

7°21.2969 W

59°48.5484 N

7°21.6007 W

Water depth

971 m

End

986 m

Fig. 6.19 Trajectory for dive M152

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Fig. 6.20 Depth profile for dive M152

M153: Dense grid survey
A 24 h survey was carried out to generate dense grid imagery of a 900 m by 370 m area (33 hectares)in the EDM, covering a total distance of 89.8 km. The survey transects consisted of 94 x 900 m longeast‐west transects mapped from 6 m altitude, with the same line spacing, cross track lines andZamboni pattern and velocity as the previous dive. Altitude tracking was performed using the altitude
range of the AUV’s ADCP.
M153 Preliminary outputs
The dive succeeded in collecting 24,943 strobe illuminated stereo pairs and 723,138 dual laser
bathymetry images. The increased altitude did not solve the problem of bottom tracking and so it was
decided that the transects should be aligned with the major axis of the mounds to minimize thesteepness of slopes encountered in future dives. The currents were stronger in the EDM resulting inlarge fluctuations in vehicle velocity, and the turbidity resulted in degradation of image quality, andso it was decided that future missions should be run at 5 m altitude.
Table 6.9 M153 dive data

Site

Darwin Mounds (West)

Mission

Ship (deploy/recovery)

In waterOn deck

Date / Time

18/09/2019

09:01:00

19/09/19

09:35:00

Coordinates (LAT/LON)

59°59.299

7°4.452

59°51.39

7°4.75

BioCam (mapping)Start

Date / Time

18/09/2019

10:53:41

19/09/2019

08:08:18

Coordinates (LAT/LON)

59°51.317 2N

7°4.5324 W

59°51.1224 N

7°4.1605 W

Water depth

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M153

End

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Fig. 6.21 Trajectory for dive M153

Fig. 6.22 Depth profile for dive M153

M155: System tests dive
A short test mission was planned at the end of a 24 h side scan mission to test different strobe
durations on image quality. This consisted of 5 x 900 m long transects at 15, 10, 6, 5, 4 m altitude.
Unfortunately, shortly after completing the side scan survey during this mission, the AUV’s ADCP failed
resulting in a loss of bottom lock and recovery of the vehicle.

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Table 6.10 M155 dive data

Site

Darwin Mounds

Mission

M155

Ship (deploy/recovery)

In waterOn deck

Date / Time

21/09/2019

15:04:00

22/09/2019

15:39:00

Coordinates (LAT/LON)

59°51.3694 N

7°9.569 W

59°50.889 N

7°8.375 W

BioCam (mapping)Start

Date / Time

22/09/2019

14:06:32

22/09/2019

14:55:18

Coordinates (LAT/LON)

59°50.1370 N

7°9.3660 W

59°50.1464 N

7°9.3438 W

End

Water depth
1041 m1063 mFig. 6.23 Trajectory for dive M155

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Fig. 6.24 Depth profile for dive M155

M156: Dense grid survey
A 24 h survey was carried out to generate dense grid imagery of a 74 0m by 450 m area (33 hectares)in the WDM, covering a total distance of 90.0 km. The survey transects consisted of 114 x 750 m long
diagonal transects mapped from 5 m altitude, with the same line spacing, cross track lines andZamboni pattern and velocity as the previous dive. The diagonal transects were aligned with the major
axis of the mounds to minimize the slope encountered by the AUV.

M156 Preliminary outputs
Failure of a communication cable between Autsub6000 and BioCam meant that the start dataacquisition command could not be sent to BioCam to start its observations. The health status monitor
system on BioCam that is forwarded via the Autosub6000’s modem had alerted the team to abnormal
behaviour during the dive. On discussion with the PSOs and MARS team, it was decided not to abortand recover under the circumstance due to the unreliable acoustic communication with the AUV, andthe fact that the deployment was late in the shift hours for the teams involved. It was also consideredthat the health status reporting could be at fault (although it had been reliable on the previous dive)and there was a risk of potentially aborting a successful mission.

Analysis of the mission logs on BioCam indicate that there was an ethernet cable failure between
BioCam and the Autosub6000 that prevented the mission start command being sent to BioCam. As aresult, no imagery could be obtained. Regarding the vehicle motion, the gentler slopes meant that
more accurate altitude keeping was achieved. Analysis of the recorded obstacle avoidance data areinconclusive regarding the effect of 150 m range horizon following using the obstacle avoidance,
however, early indications are that this would not cause the same undulating effects seen at lower
altitudes of 2 m in past expeditions.

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Table 6.11 M156 dive data

Site

Darwin Mounds

Mission

M156

Ship (deploy/recovery)

In waterOn deck

Date / Time

24/09/2019

13:30:00

25/09/2019

15:54:00

Coordinates (LAT/LON)

59°49.426 N

7°21.631 W

59°49.85 N

7°22.666 W

BioCam (mapping)Start

Date / Time

‐

‐

‐

‐

Coordinates (LAT/LON)

‐

‐

‐

‐

Water depth

958 m

End

941 m

Fig. 6.25 Trajectory for dive M156

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Fig. 6.26 Depth profile for dive M156

6.2.4. Results
The overall numbers of data collection are summarized in the following table:
Table 6.12 Summary of collected data

Dive
Stereopairs
Laser lines
Area
mapped(hectares)
Area coverrate (m2/h)

M150
2678

M151
2392

M152
42,558M153
50,850

M155
1896

M156
0

Total
100,374

106,0421

103,9841

1,210,490
29

1,446,284
33

45,48200064

16,30015,5002,912,282

6.2.4.1. Three dimensional reconstructions
Stereo and Structure from motion 3D reconstructions

The ACFR stereo pipeline was used to generate 3D reconstructions of the dense grid survey
carried out during M152. The map measures 29 hectares, with edge lengths of 900m and
320m, providing broader scale context regarding the distribution of coral and habitats aroundthe 10 mounds covered in the survey area. The details show some of the features that were
mapped during the dive.

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Fig. 6.27 3D reconstruction generated from M152 data
Laser reconstruction
The area around the whale fall (59.8179, ‐7.3601, depth 956m) that was captured during the M152
dive was reconstructed using the laser scanning pipeline, and the resulting 3D reconstruction isshown in Fig. 6.28. The reconstruction shows that the length of the skeleton is 7.51m, the widest
part of the skull is 1.03m and the highest protrusion above the seafloor measures 0.26m

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Fig. 6.28 3D reconstructed of the whale carcass using laser scanning bathymetry.

6.2.4.2. Structure from motion
By applying Structure from Motion (SfM) using commercially available software (Agisoft Metashapefrom https://www.agisoft.com/) to several subsets of undistorted colour and greyscale images, it waspossible to obtain detailed 3D reconstructions of the whale carcass (Fig. 6.29) and some coral patches(Fig. 6.30).

Fig. 6.29 3D reconstruction of whale carcass using SfM.

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Fig. 6.30 3D reconstruction at the base of a coral mound located at 59.8139 ‐7.357. The left side shows
the mesh generated from the imagery and the right side shows the texture map overlayed onto themesh.

6.2.4.3. Results of unsupervised clustering and image query
The broad scale distribution of habitats on the seafloor was characterised using an unsupervised
clustering algorithm currently being developed at the University of Southampton (Yamada et al., in
preparation). The algorithm uses a deep‐convolutional neural network to learn representative
features from each image dataset. The learnt features are used to:organise entire datasets into similar classes, or topics
enable specific images to be queried based on their similarity index.
Unlike supervised learning methods, this approach does not require human labelled training data,
which form a major limitation for supervised approaches. It instead relies on features that are intrinsic
to the image dataset itself, allowing broad scale spatial patterns to be identified within expedition
relevant time frames. While the clustering separates images into similar regions and can highlightspatial patterns, the ability to query the dataset by presenting the algorithm with a series of images
showing specific features of interest allows humans to look for spatial patterns in a more targeted
way. The criteria used by the algorithm are the same as that used for clustering, and so require no
human labelled training data.
Fig. 6.31 shows the 21,279 colour images collected during the M152 dive organised according to the
topic, and the t‐distribution Stocastic Neighbourhood Embedding (t‐SNE) feature space generated thathas been extracted from the data and used as a basis for clustering and image queries. The topics
identified are meaningful to human experts, and broadly align with rippled sand (blue, light blue,
orange, green, beige), xenophyophores (lime green, red), and coral (pink, purple). The vast majorityof images show rippled sand, highlighting the fact that spatially discretising the survey area would notprovide a representative overview of each habitat that exists at this site. Fig. 6.32 shows the spatial
distribution of these classes alongside a series of representative summaries for each image topic
identified by the algorithm.
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Fig. 6.31 Images taken during the expedition organised by unsupervised topic class (left), and thecorresponding t‐SNE feature space showing the different topics (right)

Fig. 6.32 Spatial distribution of the different topics identified by the unsupervised clustering
algorithm(left), and representative summaries (right) where the corresponding colours in Fig. 6.31
have been used.

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While this representation provides an effective method to rapidly summarise the multihectare scalespatial distributions seen in the imagery, a more targeted basis for analysis can be achieved using thesame feature space to query specific images of interest. Fig. 6.33 shows the results of a query search
for an image showing live coral. The image matrix in the centre of the figure organises other images
in the dataset by their similarity to the query images, going from top left to right, and then top tobottom. The image on the right shows the spatial distribution of similar looking images, where yellow
shows images that are most similar.

Fig. 6.34 shows the distribution of images similar in appearance to a) live cold‐water‐coral, b) coralfragments, c) densely distributed xenophyophores and d) sparsely distributed xenophyophores. The
query images, detailed excerpts and maps cover the entire range of spatial scales observed from justunder 10 mm2 to several tens of hectares, equivalent to the scale of a single blade of grass going up
to multiple football stadiums. The cold‐water corals are found mainly at the base and slopes of themounds, with coral fragments found on the mounds and forming long tails in the northeast to
southwest direction. Xenophyophores are found at the base of the mounds, following the tails with ahigher density near to the mounds, and lower density found further away from their base.

Fig. 6.33 Results of a query search for coral. The red circle identifies the image that was used as aquery. The yellow colour in the spatial representation indicates the presence of similar images.

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Fig. 6.34 Panels show respectively, cold‐water coral, coral fragments, densely distributed
xenophyophores, sparsely distributed xenophyophores together with their query images.

6.2.4.4. Open access via Squidle+
Imagery collected using BioCam during this expedition will be made publicly available throughSquidle+ (http//soi.squidle.org), a web‐based image annotation platform, under campaign dy108‐109_nerc_oceanids_class.

6.2.5. Conclusion and future recommendations
The engineering objectives for the BioCam project have been successfully achieved.


Autosub6000 mounted BioCam has demonstrated TRL8 performance through successful
collection of scientifically meaningful datasets from 1000 m depth at the Darwin Mounds.
Over the deployments, the device demonstrated robust performance of both its hardware
and software systems and succeeded in collecting 45,606 strobe illuminated stereo pair
images of the seafloor and 1,349,127 dual laser bathymetry lines, corresponding to 5830
million points of millimetre resolution 3D information. The platform and sensor wereoperationally reliable, with safety mechanisms to automatically turn off lasers in the event of
any abnormality through a software watchdog and use of a magnetic kill switch removed aspart of the recovery procedure, allowing for safe operation of the device.
The mission failsafe procedure and health status monitoring capabilities were effective during
the dives. In the final dive, where there was a pressure failure of the commercial
communication cable between BioCam and Autosub6000, BioCam’s health status signal

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successfully alerted the operating teams to an abnormality through Autosub6000’s acoustic
communication during the mission, although the decision made was not to abort the mission.
The Autosub6000 and RRS Discovery navigational logs were successfully integrated into
BioCam’s data processing pipelines, allowing datasets collected to be processed andreconstructions produced and machine‐based interpretations to be conducted effectively
during the expedition. This contributed to the discovery and accurate localization of apreviously unknown whale carcass within the WDM survey area. The discovery was featuredby the BBC news during the expedition (see section 6.7). 3D reconstructions of the observed
scenes also informed strategies for improved data collection using the Autosub6000 during
the expedition.



Autosub6000 is capable of accurate bottom tracking at an altitude of 5 m in the terrains foundat the Darwin Mounds and collecting continuous cover dense grid datasets by using a modified
Zamboni pattern with a minimum turn diameter of 30 m. AUV transects should be alignedwith the major axis of the mounds (or any other protruding features) as much as possible tominimize the slopes encountered during the dive.
The impact of using Autosub6000’s 150m range forward looking obstacle avoidance sonar
during high altitude imaging using BioCam remains unclear. Early indications from the datacollected suggest that the undulating effects reported in missions at lower altitude are lesslikely to happen. However, the tests conducted here without actually performing obstacle
avoidance remain inconclusive, and future tests should be carried out to verify horizon
tracking obstacle avoidance impact on data quality. For areas with bathymetry similar to theDarwin Mounds (i.e. mainly flat with 5m high peaks of 100m diameter), the indication is thatsafe missions are possible without the obstacle avoidance provided the AUV tracklines arealigned with the most gently slope.
Maintaining a 30 m diameter turning circle (natural minimum turning of Autosub6000) allows
usable image data to be collected for the entire length of a transect. While initial missions
were designed to allow for a 150 m overshoot either side of the observation area, this wasfound not to be necessary, and the overshoot needs only to be the length of the turn radiusin terrains encountered at the Darwin Mounds.
An average area coverage rate of 15,900 m2/h was achieved during dense grid surveys. This islower than the maximum possible (40,000 m2/h) with single swath transect surveys due to theoverlap required between adjacent survey lines to collect dense grid surveys. However, themapping rate still represents an order of magnitude increase in area covered compared toconventional ROV and hover capable AUV seafloor imaging surveys.

The data collected during this expedition is suitable for future engineering development ofmethods to improve colour and dimensional accuracy of reconstructions and AUV localization
estimates, and automated feature segmentation. Topic‐based unsupervised classificationand query algorithms run during the expedition demonstrate how these methods can be used
to identify broader scale patterns and highlight interesting scenes in the data.

The following scientific objectives have been achieved.
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Multi‐hectare scale 3D imagery of cold‐water corals and the surrounding local ecology has
been successfully collected using BioCam. The preliminary data and information products
produced during the expedition illustrate spatial distribution patterns of the coral around themounds over scales that are significantly larger than a single image frame.

The size of the surveyed areas is in the order of several hundreds of metres along each axis.
This is significantly larger than the uncertainty associated with underwater localization,
indicating that exactly overlapping image datasets can be obtained for future repeat
observations and quantitative temporal studies in future expeditions.



The datasets collected have been processed and made ready to upload onto the web based
open access annotation platform Squidle+ to allow members of the scientific community toanalyse its results. This was carried out during the expedition and was limited only by internet
bandwidth to upload the data from the ship. Ships with significantly faster internet
connections are available, demonstrating that data with its associated metadata can bedisseminated to the broader scientific community during an ongoing expedition.

The habitat maps and classes derived from BioCam data may have potential implications formonitoring. The following points should be considered in this context.
Structuring analysis: Derived habitat classes may be useful for grouping physical seafloor
samples or imagery. It is necessary to explore the potential for:o Making comparisons of measurements made in across different habitat types.
o Targeting labelling efforts to allow for balanced treatment across different habitat
types, especially in cases where the spatial coverage of individual habitats is different.
o Use of query functions to focus efforts for more detailed studies on specific groups ofspecies or habitats of interest.

Planning observations: The analysis and visualisation of spatial patterns can be robustly
carried out during expedition relevant time frames (from same day to a week). This may be
useful for making more targeted sampling efforts, for example, by making more evenly
balanced observations across different habitat types.



Repeat monitoring: Traditionally, co‐registered visual observations have been limited to time‐
lapse images and point wise measurements with a small footprint of several metres. Repeat
observations with BioCam have the potential to make co‐registered visual observations thatcan be direct comparisons over multi‐hectare spatial scales.



Multi‐resolution analysis: The millimetre order resolution observations made by BioCam covera larger area than traditional imaging surveys, but at the same time, sacrifice some resolution
compared to sub‐millimetre resolution imagery obtained by ROVs and hover capable
platforms.
o The implications of resolution on observable features, and area cover, on statisticalrobustness when computing the types of ecological variable used in monitoringshould be studied.
o The resolution and visual context of BioCam imagery can be used to ground truth
inferences made from AUV side scan and multibeam surveys, which cover larger areas
at lower resolutions (tens of centimetres to metres). The correlation between

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overlapping measurements made by these approaches may be useful to study how
habitats can be robustly inferred over regional scales.

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6.3. Megafauna community study from seabed observations (Nils Piechaud,
Guillem Corbera, James Strong, Brian Bett)
The ‘Hydraulic Benthic Interactive Sampler’ (HyBIS) is a modular, versatile, towed robotic underwater
vehicle (RUV) capable of reaching depths of 6000 metres, developed and operated by the NOC (seealso section 7.2). Controlled via fibre optic cable connected to the ship, HyBIS is equipped with twocameras (HD Scorpio and a low resolution ‘tooling’ camera) and a forward‐facing sonar. The main
module consists of the steering unit represented by two propellers as well as the energy supply, thecameras, the light, the hydraulic systems and the telemetry. Depending on the sampling requirements,
different modules can be mounted under the main module.
In contrast to a conventional remotely operated vehicle (ROV), HyBIS is not neutrally buoyant. Boththe descent and the ascent of the HyBIS, as well as the operating depth are controlled from the ship
through the fibre optic cable. Therefore, HyBIS can deploy and recover a net load up to 700 kg(sampling equipment and sampling material), which is several times the payload of an ROV.
HyBIS navigation is through USBL (Sonardyne Ranger), and is visualised in real‐time on the OFOP
software (Ocean Floor Observation Protocol). The software also provides the opportunity to annotate
and log the video in real time.
During DY108, a total of 11 HyBIS dives were successfully completed. Dives 51, 53, 54, 56 and 60 wereconducted at Darwin Mounds East. Dives 52, 55, 57, 58, 59 and 61 were performed at Darwin Mounds
West. A brief summary of each dive is provided below.
6.3.1. Dive 51: Darwin Mounds East (1050 – 1058 m; moderate visibility and current strength)
Objective of the dive: repeat the historical track collected during 2011 and find the settlement panel
mooring.
The majority of the substrata at this station was a silty sand lacking surface ripples (Fig. 6.35a and b).
The sandy substratum, and areas in the lee side of coral mounds, contained numerous Xenophyopores(approximately 2‐3 ind per m2). Squid, cutthroat eels (Synaphobranchidae) and gelatinous
zooplankton appeared abundant in the water column. Epifaunal species, in approximate order ofdecreasing abundance, included pencil and fine‐spined urchins (Echinoidea), brittlestars (Ophiuroids),
Hexactinellid sponges, anemones (mainly Cerianthids) and squat lobsters (Galatheoids). The HyBIS
track crossed five substantial mounds (Fig. 6.36). Coral mounds were covered in small coral rubble
pieces with little live coral (only small colonies of both Madrepora oculata and Lophelia pertusa – see
Fig. 6.37). The coral colonies were occasionally accompanied by the hexactinellid sponge
Aphrocallistes sp., a taxon known to be associated to cold‐water coral mounds. Marine litter was
relatively infrequent and composed of plastic bags, bottles and small sections of fishing net. The North
Atlantic codling (Lepidion eques) was common in areas containing coral. Chimera (probably Chimaera
monstrosa) were occasionally observed both on sand and on coral mounds. The mooring withsettlement panels was successfully located and logged for later retrieval.

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Fig. 6.35a and b. Typical sandy substratum with abundant Xenophyopores observed in HyBIS dive 51.

Fig. 6.36 Final OFOP map showing the tracks of the ship (orange) and HyBIS (blue) for dive 51. The
historical track is colour‐coded; dark green for sand with Xenophyopores, green for sand with pebbles
and light green for just sand, yellow for coral rubble and red for live coral. The other colour coded track
represents the 2011 version of track 60.

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Fig. 6.37 The distribution of live colonial scleractinian coral observations (Madrepora oculata andLophelia pertusa), shown as red points, along the route of HyBIS dive 51 (light green points).

6.3.2. Dive 52: Darwin Mounds West (969 m; moderately poor visibility and high current speeds ‐spring tide)
Objective of the dive: recover one of the settlement panel moorings (59° 48.829 N 7° 21.609W)
HyBIS was used to successfully recover the settlement panel mooring deployed in 2011. A fulldescription of the mooring and its biofouling community can be found in Section 6.5.

6.3.3. Dive 53: Darwin Mounds East (952 m; moderately poor visibility and high current speeds ‐spring tide)
Objective of the dive: recover the second mooring with settlement panels (59° 50.932 N 7° 3.538 W).
HyBIS was used to successfully recover the settlement panel mooring deployed in 2011. A fulldescription of the mooring and its biofouling community can be found in Section 6.5.

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6.3.4. Dive 54: Darwin Mounds West (945 – 965 m; moderately poor visibility and high current
speeds ‐ spring tide)
Objective of the dive: repeat ROV track collected in 2011.
The majority of the transect was a sandy substratum with distinct areas of straight, sinuous andsurface ripples, although areas lacking ripples were also observed. A short patchy turf was often
associated with sandy areas lacking surface texture, which was assumed to be abundant polychaete
tube worm tubes. Squid, cutthroat eels (Synaphobranchidae) and gelatinous zooplankton appeared
abundant in the water column. Epifaunal species, in approximate order of decreasing abundance,
included tube‐dwelling anemones (Cerianthids) and epifaunal anemones (including the Venus fly trap
anemone Phelliactis sp.), brittlestars (Ophiuroidea), pencil and fine‐spined urchins (Echinoidea),
starfish (Asteroidae); gorgonians (Gorgonacea), sponges and squat lobsters (Galatheoids).
The HyBIS track crossed four substantial coral mounds (Fig. 6.38), which were covered in a moderateamount of small to medium sized coral colonies (Figs. 6.39 and 6.40). Madrepora oculata appeared tobe more abundant than Lophelia pertusa on the coral mounds. The coral colonies were occasionallyaccompanied by the hexactinellid sponge Aphrocallistes sp., a taxon known to be associated to cold‐
water coral mounds. Marine litter was encountered on several of the mounds and included plastic
debris and fishing gear (Fig. 6.39b). Fish, such as the North Atlantic codling (Lepidion eques) and theroundnose grenadier (Coryphaenoides rupestris) were common in areas containing coral. Chimera(probably Chimaera monstrosa) were occasionally observed both on sand and on coral mounds.

Fig. 6. 38 Final OFOP map showing the tracks of the ship (orange) and HyBIS (blue) for dive 54. The
historical track is colour‐coded; dark green for sand with Xenophyopores, green for sand with pebbles
and light green for just sand, yellow for coral rubble and red for live coral.
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Fig. 5.39a and b. Moderate sized colony of coral (left) and a similar colony with fouled fishing gearfrom HyBIS dive 54.

Fig. 6.40 The distribution of live colonial scleractinian coral observations (Madrepora oculata andLophelia pertusa), shown as red points, along the route of HyBIS dive 54 (light green points).

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6.3.5. Dive 55: Darwin Mounds West (963 – 971 m; moderately poor visibility and high current
speeds ‐ spring tide)
Objective of the dive: repeat ROV track collected in 2011.
The majority of the transect was dominated by a sandy substratum, often with a discontinuous or
lobate pattern suggesting localised increases in hydrodynamic energy. The rest of the sandy
substratum lacked surface texture but did have substantial densities of small polychaete tubeworms.
Xenophyopores were moderately abundant on both rippled and featureless areas. As with all HyBIS
stations on the Darwin Mounds, squid and cutthroat eels (Synaphobranchidae) were abundant.
Epifaunal species, in approximate order of decreasing abundance, included brittlestars and starfish(Ophiuroidea and Asteroidae), pencil and fine‐spined urchins (Echinoidea), tube‐dwelling anemones(Cerianthids), gorgonians (Gorgonacea), sponges and hermit crabs with shells covered in Epizoanthids.
A large sponge of the genus Geodia was also observed during this dive, a not very common taxon inthis region.
The HyBIS track crossed three coral mounds and passed over the flanks of four other mounds (Fig.
6.41). Small and large pieces of coral rubble were present on the top of the mounds (Figs. 6.42 and6.43). Coral mounds were also covered in a moderate amount of medium and occasionally large sizedcoral colonies (comprised mainly of Madrepora oculata and some Lophelia pertusa). The coral colonies
were occasionally accompanied by the hexactinellid sponge Aphrocallistes sp., a taxon known to be
associated to cold‐water coral mounds. Marine litter was encountered on several of the mounds andincluded plastic debris and a tin can. The North Atlantic codling (Lepidion eques) was common in areas
containing coral whereas the roundnose grenadier (Coryphaenoides rupestris) was less frequently
seen. Chimera (Chimaera monstrosa) were occasionally observed mainly on sand and occasionallynear coral mounds.

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Fig. 6.41 Final OFOP map showing the tracks of the ship (orange) and HyBIS (blue) for dive 55. The
historical track is colour‐coded; dark green for sand with Xenophyopores, green for sand with pebbles
and light green for just sand, yellow for coral rubble and red for live coral.

Fig. 6.42. Sparse coral colonies on a mound during dive 55.

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Fig. 6.43 The distribution of live coral observations (Madrepora oculata and Lophelia pertusa), shown
as red points, along the route of HyBIS dive 55 (light green points). The presence of living coral a few
meters away from the mound structures represented in the side‐scan sonar might indicate a positional
inaccuracy of the latter.

6.3.6. Dive 56: Darwin Mounds East (1045 – 1058 m; moderate visibility)
Objective of the dive: repeat ROV track collected in 2011.
The majority of the substratum on this dive was a silty sand mostly lacking surface ripples. Numerous
Xenophyopores were present on the sandy substratum and densities increased markedly in the leeside of coral mounds. Squid and cutthroat eels (Synaphobranchidae) were abundant throughout thedive. Epifaunal species, in approximate order of decreasing abundance, included tube‐dwelling
anemones (Cerianthids), brittlestars (Ophiuroidea), fine‐spined urchins (Echinoidea), sea cucumbers(Stichopodidae) and gorgonians (Gorgonacea). An isolated specimen of the genus Pheronema was also
observed during this dive. Aggregations of this species are considered vulnerable marine ecosystems(VME).
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The HyBIS track crossed nine mounds (Fig. 6.44). Coral mounds were covered in small coral rubble
pieces with only a low density of small colonies of both Madrepora oculata and Lophelia pertusa (Fig.
6.45 and 6.46). The coral colonies were occasionally accompanied by the hexactinellid sponge
Aphrocallistes sp., a taxon known to be associated to cold‐water coral mounds. Marine litter, which
was relatively infrequent when compared with Darwin Mounds West, included plastic debris andfishing gear. The North Atlantic codling (Lepidion eques) was common in areas containing coral andlarge accumulations of larger rubble. Chimera (Chimaera monstrosa) were occasionally observed bothon sand and on coral mounds.

Fig. 6.44 Final OFOP map showing the tracks of the ship (orange) and HyBIS (blue) for dive 56. The light
blue line is the planned transect line for the HyBIS dive. The historical track is colour‐coded; dark green
for sand with Xenophyopores, green for sand with pebbles and light green for just sand, yellow forcoral rubble and red for live coral.

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Fig. 6.45 Typical summit of a coral mound during dive 56 at Darwin Mounds East.

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Fig. 6.46 The distribution of live coral observations (Madrepora oculata and Lophelia pertusa), shown
as red points, along the route of HyBIS dive 56 (light green points).

6.3.7. Dive 57: Darwin Mounds West (958 – 973 m; moderate visibility)
Objective of the dive: repeat ROV track collected in 2011 and look for a whale carcass previously
detected during a Biocam mission using Autosu6000.
The majority of the transect was over a sandy, rippled substratum with fewer Xenophyopores thanobserved in other stations. As per the entire Darwin Mounds area, squid and cutthroat eels
(Synaphobranchidae) were abundant throughout the dive. Epifaunal species on sand, in approximate
order of decreasing abundance, included pencil and fine‐spined urchins (Echinoidea), tube‐dwelling
anemones (Cerianthids), brittlestars and starfish (Ophiuroidea and Asteroidae) and sea cucumbers(Stichopodidae).
The HyBIS track crossed five mounds (Fig. 6.47). Both Madrepora oculata and Lophelia pertusa were
present on most mounds (Fig. 6.48). Some mounds had what appeared to be high densities of
echiurans, generally in the surroundings of the coral colonies (Fig. 6.49). A small, isolated stand ofcoral was also found within a sand plain (identified as a small, bright spot on an acoustic image). The
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coral colonies were occasionally accompanied by the hexactinellid sponge Aphrocallistes sp., a taxon
known to be associated to cold‐water coral mounds. Litter was present at almost all of the significant
concentrations of coral (Fig. 6.50a and b) and typically comprised of plastic packaging. The North
Atlantic codling (Lepidion eques) was common in areas containing coral. Chimera (Chimera monstrosa)
were occasionally observed both on sand and on coral mounds. The same HyBIS dive was used tolocate the whale fall observed in the Autosub/BioCam mission. As such, only half of the historical track
was repeated, i.e. waypoints 1 – 6 completed.
Despite the intense efforts from the scientist team and HyBIS technicians the whale carcass could not
be spotted during this dive.

Fig. 6.47 Final OFOP map showing the tracks of the ship (orange) and HyBIS (blue) for dive 57. The light
blue line is the planned transect line for the HyBIS dive. The historical track is colour‐coded; dark green
for sand with Xenophyopores, green for sand with pebbles and light green for just sand, yellow forcoral rubble and red for live coral.

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Fig. 6.48 The distribution of live coral observations (Madrepora oculata and Lophelia pertusa), shown
as red points, along the route of HyBIS dive 57 (light green points).

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Fig. 6.49 High density of spoon worms (echiurans) on top of a coral mound during dive 57.

Fig. 6.50a and b. Branded plastic litter seen during dive 57 (left) and more plastic litter during the same
dive (right).

6.3.8. Dive 58: North of Darwin Mounds West (965 ‐ 980 m; moderate currents and visibility)
Objective of the dive: repeat the historical WASP track (southern transect moving east) and examine
new mounds (northern transect moving west).
This site was previously examined with the WASP drop‐down system in 1999 (Fig. 6.51). This station
has distinct coral mounds and extensive areas of sparse coral (Fig. 6.52). During the southern part of
the transect, the sand substratum had a significant topping of gravel but with no surface rippling.
Unlike both Darwin Mounds East and West, there was a general absence of Xenophyopores with somesporadic individuals. Epifaunal species, in approximate order of decreasing abundance, included pencil
and fine‐spined urchins (Echinoidea), tube‐dwelling anemones (Cerianthids), gorgonians(Gorgonacea), brittlestars and starfish (Ophiuroidea and Asteroidae), sea cucumbers (Stichopodidae)
and various sponges.

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The northern transect (running east to west) ran over and between some large and densely colonised
mounds (Fig. 6.52). Generally, M. oculata appeared to be more abundant than L. pertusa. The coralcolonies were occasionally accompanied by the hexactinellid sponge Aphrocallistes sp., a taxon known
to be associated to cold‐water coral mounds. Sand running between these mounds occasionallyformed channels of heavily rippled sand, often with extreme sharp boundaries between ripple andunrippled sand (Fig. 6.53a). Some of these sedimentary features could be part of a larger structure,such as barchan dunes. These features might be related to faster currents nearer the Wyville Thomson
Ridge or occasional overflow of cold arctic water over this ridge. Coral density and height superficiallyappeared to be greater here than elsewhere in the West (Fig. 6.53b). Besides the coral colonies locatedon the mounds, some off‐mound sparse coral aggregations were observed, one of them being of aconsiderable size (approximately 3 – 4 m across and more than a meter tall) (Fig. 6.53c). The North
Atlantic codling (Lepidion eques) was common in areas containing coral. Chimera (Chimaera
monstrosa) were occasionally observed both on sand and on coral mounds. Marine litter, typicallyplastic debris (Fig. 6.54a) was frequently encountered and especially abundant within stands of dense
coral. A large fishing net, approximately 30 – 40 m long, was found attached to a small, but surprisingly
healthy, coral outcrop (Fig. 6.54b). The net was sparsely covered with barnacles and coral could beseen growing through the net mesh. The HyBIS video track roughly corresponded to the TOBI acoustic
image (the acoustic image was perhaps shifted north north‐west by 70 ‐ 100 m).

Fig. 6.51 Final OFOP map showing the tracks of the ship (orange) and HyBIS (blue) for dive 58. The light
blue line is the planned transect line for the HyBIS dive. The historical track is colour‐coded; dark green
for sand with Xenophyopores, green for sand with pebbles and light green for just sand, yellow forcoral rubble and red for live coral.

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Fig. 6.52 The distribution of live coral observations (Madrepora oculata and Lophelia pertusa), shown
as red points, along the route of HyBIS dive 58 (light green points).

Fig. 6.53a, b and c. A distinct boundary between untextured sand and ribbons of heavily rippled sandthat runs between coral mounds during the northern ad hoc transect (left) and a typical coral moundfrom the same area (right). Large off‐mound aggregation of M. oculata with some patches of L. pertusa(down).
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Fig. 6.54a and b. Plastic or fabric litter caught on coral (left) and part of the fishing gear (59° 53.00320
N 007° 4.37176 W) caught on coral along the northern ad hoc transect.

6.3.9. Dive 59: North of Darwin Mounds West (943 ‐ 961 m; moderate to high visibility)
Objective of the dive: repeat ROV track collected in 2011 and examine new mounds north of thetransect.
The majority of the transect was on a sandy substratum, with some areas having an undulatory(rippled) surface. Although heterogeneous, there was a moderate density of Xenophyopores on boththe sand and on some coral mounds. Further north, the sandy substratum started to form intomegaripples – these features were obvious in the existing sidescan sonar data and in the forward‐
facing sonar on HyBIS but not in the camera footage. Dense fields of small, polychaete
tubeworms/amphipod tubes were often associated with areas of featureless sand. Squid andcutthroat eels (Synaphobranchidae) were abundant throughout the dive. Epifaunal species associatedwith the sand, in approximate order of decreasing abundance, included tube‐dwelling anemones(Cerianthids), pencil (Cidaris cidaris) and fine‐spined urchins (Echinoidea), brittlestars and starfish(Ophiuroidea and Asteroidae) and squat lobsters (galatheoids). Chimera (Chimaera monstrosa) wereoccasionally observed more over sandy substrata.
The planned track crossed eight coral mounds (Fig. 6.55). Mounds typically had a low to medium
density of small to medium sized coral patches (Fig. 6.56). The majority of the live coral on the mounds
was dominated by M. oculata (both orange and white morphs) with smaller quantities of L. pertusa.
Sponges and gorgonians were frequently present with the live coral. The coral colonies wereoccasionally accompanied by the hexactinellid sponge Aphrocallistes sp., a taxon known to be
associated to cold‐water coral mounds. Epifaunal species associated with the coral included Brisingida
starfish (large aggregation of these asteroids on one of the mounds) (Fig. 6.57), large anemones, spoon
worms (Echiurians) and crinoids. As per most mounds in the West, marine litter such as plastic
sheeting, fishing gear and bottles was present on numerous coral mounds. The North Atlantic codling(Lepidion eques) was common in areas containing coral, whereas the roundnose grenadier(Coryphaenoides rupestris) was only occasionally sighted.

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Fig. 6.55 Final OFOP map showing the tracks of the ship (orange) and HyBIS (blue) for dive 59. The
light blue line is the planned transect line for the HyBIS dive. The historical track is colour‐coded; darkgreen for sand with Xenophyopores, green for sand with pebbles and light green for just sand, yellow
for coral rubble and red for live coral.

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Fig. 6.56 The distribution of live coral observations (Madrepora oculata and Lophelia pertusa), shown
as red points, along the route of HyBIS dive 59 (light green points).

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Fig. 6.57 Unusual abundance of Brisingida in an on‐mound coral patch.

6.3.10. Dive 60: North of Darwin Mounds East (1048 ‐ 1060 m, moderate to high visibility)
Objective of the dive: repeat ROV track collected in 2011 and examine a new area south of thetransect.
The majority of the transect was on a sandy substratum lacking surface texture. Xenophyopores werecommon throughout the dive although their abundance did decline on coral mounds. Dense fields ofsmall, polychaete tubeworms /amphipod tubes were often associated with areas of untextured sand.
As per all HyBIS dives, squids were common and cutthroat eels (Synaphobranchidae) abundant
throughout the dive. Epifaunal species associated with the sand, in approximate order of decreasing
abundance: tube‐dwelling anemones (Cerianthids), brittlestars and starfish (Ophiuroidea andAsteroidae), pencil (Cidaris cidaris) and fine‐spined urchins (Echinoidea), and squat lobsters(galatheoids). Approximately 4‐5 seapens were also encountered during the dive.
During the descent, a large elasmobranch (possibly Lamna nasus) appeared in both of the HyBIS
cameras. Chimera (Chimaera monstrosa) were occasionally observed over sandy substrata. A large
monkfish (Lophius piscatorius) was also observed on the seabed during the dive.
The planned track crossed about seven significant coral mounds (Fig. 6.58). Mounds were similar toother mounds in the area with large quantities of coral rubble and gravel but little live coral (Fig. 6.59).
Live colonies were typically small and comprised of M. oculata with smaller quantities of L. pertusa.
Due to the lack of live coral, epifaunal species associated with the coral were not particularly common
or diverse but did include gorgonians, brisingida starfish, large anemones, spoon worms (Echiurians)
and crinoids. Marine litter, such as plastic sheeting, fishing gear and plastic bottles, were present on
the coral mounds. The North Atlantic codling (Lepidion eques) was common in areas containing coraland higher densities of coral rubble.

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Fig. 6.58 Final OFOP map showing the tracks of the ship (orange) and HyBIS (blue) for dive 60. The
light blue line is the planned transect line for the HyBIS dive. The historical track is colour‐coded; darkgreen for sand with Xenophyopores, green for sand with pebbles and light green for just sand, yellow
for coral rubble and red for live coral.

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Fig. 6.59 The distribution of live coral observations (Madrepora oculata and Lophelia pertusa), shown
as red points, along the route of HyBIS dive 60 (light green points).

6.3.11. Dive 61: North of Darwin Mounds West (902 ‐ 924 m; moderate to high visibility)
Objective of the dive: Investigate new area to the west of the areas surveyed in 2011.
The majority of the dive crossed a sandy substratum, with most areas having an undulating, rippled
surface. The density of Xenophyopores was much lower on sand with textured surfaces and on coralmounds. Although patchy, small tube dwelling amphipods or polychaetes were common on almost all
sandy substrata, although densities were lower on textured sand surfaces. Squids and cutthroat eels
(Synaphobranchidae) were abundant throughout the dive. Epifaunal species associated with the sand,in approximate order of decreasing abundance, included pencil (Cidaris cidaris) and fine‐spined
urchins (Echinoidea), brittlestars and starfish (Ophiuroidea and Asteroidae), tube‐dwelling anemones(Cerianthids) and squat lobsters (Galatheoids). Chimera (Chimaera monstrosa) were occasionallyobserved over sandy substrata.
The planned track crossed nine small and medium‐sized coral mounds (Fig. 6.60). The majority of themounds during the first two‐thirds of the dive were covered in high concentrations of coral gravel andCruise report No. 66

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rubble, with only occasional patches of small colonies (more often M. oculata than L. pertusa). Manyof these mounds looked heavily abraded and superficially similar to those seen at Darwin Mounds
East. Later in the dive mounds did have a greater density of live coral, and many of the colonies werelarger than seen earlier in the transect (Fig. 6.61). Epifaunal species associated with the coral included
sponges, gorgonians (Gorgonacea), various anemones, spoon worms (Echiurians) and crinoids. As per
most mounds in the West, marine litter such as plastic sheeting, fishing gear and bottles were present.
The North Atlantic codling (Lepidion eques) was common in areas containing coral rubble and live
coral. The roundnose grenadier (Coryphaenoides rupestris) was only sighted occasionally during thedive.

Fig. 6.60 Final OFOP map showing the tracks of the ship (orange) and HyBIS (blue) for dive 61. The light
blue line is the planned transect line for the HyBIS dive.

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Fig. 6.61 The distribution of live coral observations (Madrepora oculata and Lophelia pertusa), shown
as red points, along the route of HyBIS dive 61 (light green points).

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6.4. Macrofauna community study from boxcores (Laurence De Clippele, Laura
Duran Suja)
Twenty‐one boxcore deployments were carried out in the west and east Darwin Mound area in an
attempt to obtain large‐volume samples of mound and tail sediments of trawled and untrawled areas
to analyse the macrofaunal biodiversity. The corer used was the NOC NMFD stainless steel, USNEL‐
type 0.25m2 boxcorer (see Section 7.3.1). It was rigged and operated with the penetration limit
removed. The mound samples were all insufficiently cohesive to support the water in the box once inair. Consequently, these samples were subject to wash‐out. Tail samples on the other hand were able
to retain the water and were subject to minor wash‐out. The “intact” areas of the recovered sedimentof the mound samples were sampled in a quantitative matter, i.e. the dimensions were measured andthis known surface area was then sieved on a 500 micron mesh, with the resultant residue fixed andpreserved in borax buffered 3.7% seawater formaldehyde. 15 boxcores were classified as successful,four as partly and two did not trigger (Fig. 6.62 and 6.63, Table 6.13).
After allowing the samples to fix for 2‐5 days in the borax buffered 3.7% seawater formaldehyde, thesamples were washed and identified to family level using a ZEISS Stemi 305 stereo microscope. After
identification the samples were transferred into glass vials on 75% Industrial Methylated Spirit (IMS).
These samples were taken on behalf of Prof J Murray Roberts and Dr Lea‐Anne Henry, from the
University of Edinburgh, to serve as a comparison to a similar set of samples collected from the Darwin
Mounds area during the 2000 RRS Discovery cruise 248 (Bett et al, 2001) and 2011 RRS James Cookcruise 060 (Huvenne, 2011). A comparison analyses of the tails versus the mound associatedbiodiversity will also be conducted.

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Fig 6.62
Photographs of boxcore surface upon recovery:(a) DY108/109_ST8_BC2; (b)DY108/109_ST9_BC3; (c) DY108/109_ST11_BC4; (d) DY108/109_ST12_BC5; (e) DY108/109_ST13_BC6
whiteboard is missing “BC6”; (f) DY108/109_ST19_BC7; (g) DY108/109_ST20_BC8; (h)DY108/109_ST21_BC9;(i)
DY108/109_ST23_BC10;(j)
DY108/109_ST24_BC11;(k)
DY108/109_ST26_BC13; (l)DY108/109_ST28_BC14; (m) DY108/109_ST29_BC15; (n)DY108/109_ST31_BC16 whiteboard station location should be “31”; (o) DY108/109_ST32_BC17
habitat type on whiteboard should be “mound”; (p) DY108/109_ST34_BC18 Station number onwhiteboard should be “34”; (q) DY108/109_ST35_BC19; (r) DY108/109_ST36_BC20; (s)DY108/109_ST38_BC21
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Cruise report No. 66

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Fig 6.63 Photographs of boxcore profiles: (a) DY108/109_ST26_BC13 (b) DY108/109_ST28_BC14 (c)DY108/109_ST29_BC15 (d) DY108/109_ST31_BC16 whiteboard station location should be “31” (e)DY108/109_ST32_BC17 habitat type on whiteboard should be “mound” (f) DY108/109_ST34_BC18
Station number on whiteboard should be “34” (g) DY108/109_ST36_BC20

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Table 6.13 Overview of boxcores taken during the cruise.
SAMPLE NR
DY108/109_ST7_BC1
DY108/109_ST2_BC2
DY108/109_ST9_BC3
DY108/109_ST11_BC4
DY108/109_ST12_BC5
DY108/109_ST13_BC6
DY108/109_ST19_BC7
DY108/109_ST20_BC8
DY108/109_ST21_BC9
DY108/109_ST23_BC10
DY108/109_ST24_BC11
DY108/109_ST25_BC12
DY108/109_ST26_BC13
DY108/109_ST28_BC14
DY108/109_ST29_BC15
DY108/109_ST31_BC16
DY108/109_ST32_BC17
DY108/109_ST34_BC18
DY108/109_ST35_BC19
DY108/109_ST36_BC20
DY108/109_ST38_BC21

Date

Location

Habitat

StationBC no.

Success

11/09/2019
11/09/2019
11/09/2019
12/09/2019
12/09/2019
12/09/2019
16/09/2019
16/09/2019
16/09/2019
17/09/2019
17/09/2019
17/09/2019
17/09/2019
18/09/2019
18/09/2019
18/09/2019
18/09/2019
19/09/2019
19/09/2019
19/09/2019
20/09/2019

WDM
WDM
WDM
WDM
WDM
EDM
WDM
WDM
WDM
EDM
EDM
EDM
EDM
EDM
EDM
EDM
EDM
EDM
WDM
WDM
WDM

mound
mound
mound
mound
mound
just next to mound
tail
tail
tail
backgroundjust next to moundmoundjust next to mound
tail
tail
tail
just next to mound
tail
mound
tail
mound

7
8
9
11
12
13
19
20
21
23
24
25
26
28
29
31
32
34
35
36
38

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21

no
mediumyes
yes
yes
medium
yes
yes
yes
yes
yes
no
yes
yes
yes
yes
yes
yes
mediumyes
mediumCruise report No. 66

Depth
(m)
966
964
968
963.5
962.4
1053
975
957
1456
1057
1055
1062.5
1052
1052
1057
1050
1053
1053
953
952
951

Dimensions
Sediment type detail
(cm)
NA
NA
50x25x10
sand with coral rubble (15%)
41x35x10
sand with coral rubble (25%)
35x35x10
sand with coral rubble (35%)
35x35x10
muddy (10%) sand (90%) with coral rubble (35%)
30x40x10
Gravelly sand
50x50x10
sandy (20%) mud (80%)
50x50x10
sandy (20%) mud (80%)
50x50x10
sandy (20%) mud (80%)
18x50x10
Gravelly sand
22x31x10
Gravelly sandNANA
19x31x10
Gravelly sand
50x50x10
sand
50x50x10
muddy (20%) sand (80%)
50x50x10
gravely sand
37x20x10
gravelly sand with a few coral rubble pieces (1%)
50x50x50 gravelly muddy (15%) sand with coral rubble pieces (3%)
19.5x23x10
sand with coral rubble (15%)
50x50x10
mud (20%) sand (80%)
9x16x10sand with one piece of rubble

Time
12:36
14:12
15:48
05:21
06:52
10:18
10:58
12:47
14:56
08:57
10:54
12:52
14:13
05:11
06:39
12:38
14:15
04:52
11:54
14:01
04:42

USBL Latdegrees
59
59
59
59
59
59
59
59
59
59
59
59
59
59
59
59
59
59
59
59
59

USBL Lat
Minutes
48.74
48.75
48.74849.10349.3892
50.98126
49:31187
49.230849.755450.9661
50.63651.03451.0334
50.9992
50.7135
50.942250.95350.9057
48.82409
48.815948.8247

USBL Londegrees
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7

USBL Lon
Minutes
21.74421.71921.71221.37221.02883.82663
21.2818
21.8687
21.4977
3.83597.57857.90497.92398.0092
8.34763.87443.6312
3.698422.51364
22.80049
22.5341

Estimatedfamily
54
62
24
38
20
15
11
15
NA
14
8
12
11
16
19
24
26
11
NA

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6.5. Settling experiment (James Strong)
Four small moorings were deployed in the Darwin Mounds during expedition JC060 in 2011, to markthe start of ROV dives and provide a clear point to return to (Huvenne, 2011). Two of the fourmoorings, those placed in the Eastern Darwin Mounds, also carried two settlement panels. Eachmooring had a steel plate anchor and a spherical glass buoy encased in two hemispherical plastic
shells. The height of the buoy above the ballast varied between moorings. Moorings were fitted withsettlement panels at 1 m and 2 m above the seabed. Settlement panels were concrete roof tiles thatwere drilled and attached to the moorings with cable ties. The objective of the deployments was toestablish whether the settlement of Desmophyllum pertusum (nom. nov Lophelia pertusa) (Linnaeus,
1758) was occurring at either site.
On initial inspection during DY108‐109 with HyBIS, it was apparent that each of the buoys had
accumulated a substantial amount of biofouling. HyBIS video footage revealed the presence ofmultiple coral species, including L. pertusa, on the buoys. As such, the decision was taken to recover
one mooring from both East and West Darwin Mounds for further inspection (Section 6.5.2) and toleave the remaining moorings for future study (Section 6.5.3).
6.5.1. Recovered settlement moorings
The two moorings (Table 6.14) were recovered with the HyBIS remote underwater vehicle. The HyBIS
frame was modified to include a snap‐carabiner, mounted on a pole and attached to the HyBIS framewith a lifting strop. Care was taken not to disturb the mooring excessively during the recovery. Closeup video observations were collected before the ascent should the mooring be lost on recovery(Darwin Mounds West buoy ‐ Figures 6.64a and 6.64b; Darwin Mounds East buoy ‐ Figures 6.65a and6.65b).
Table 6.14 Details of the settlement moorings at Darwin Mounds East and West.
Darwin Mounds West
JC060‐30‐Mark‐02
16/05/2011 21:46
52
12/09/2019 ~ 19:21
968 m
59° 48.86417 N
007° 21.54315 W

Darwin Mounds East
JC060‐50‐Mark‐04
21/05/2011 23:00
53
12/09/2019 ~23:25
1058 m59° 50.93434 N
007° 3.53917 W

Buoy height above the seabed
Settlement panels

6m
N/A

Moorings remaining in place

1

4.5 m
1 m and 2 m above seabed(2 m panel lost on recovery)
1

Original station numbers
DeployedHyBIS dive
Recovered to deck
Depth
Position

6.5.1.1. Visual inspection of the recovered moorings in situ
The ballast weight was not colonised whilst the mooring rope was covered in a dense hydroid turf.
The buoys at both sites were predominantly covered in large barnacles as well as a variety of mobile
epifaunal species such as urchins (Echinoidea), hermit crabs (Paguroidea), gastropods (Gastropoda),
brittlestars (Ophiuroides) and shrimp (Pandalus sp.) ‐ much of this was lost during the ascent.

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Fig. 6.64 a & b Darwin Mounds West buoy on seabed (left) and close‐up of buoy during ascent (right).

Fig. 6.65 a & b. Darwin Mounds East buoy on seabed showing the location of the two settlement panels
near the base of the mooring (left) and close‐up of buoy during ascent (right).

6.5.1.2. On‐deck observations of the mooring from Darwin Mounds West
The buoy was completely covered in biofouling and several of the mobile epifaunal species were still
attached to the buoy (i.e. urchins and numerous brittlestars). Barnacles dominated the buoy in termsof both cover and biomass (Fig. 6.66, Fig. 6.67a). Noteworthy members of the biofouling community
included:








Four colonies of L. pertusa attached to the buoy ‐ each colony was between 25 ‐ 95 mm inheight and contained multiple polyps. Colonies were mostly growing on barnacle plates.
Numerous individual Desmophyllum sp. polyps were interspersed through the barnacle cover(Fig. 6.67b).
Many small orange, Chlamys‐like species, pectinids were scattered over the barnacle
encrustment .
Ophiuroids were abundant across the surface of the buoy (approximately in the low to mid
hundreds).
Polychaete worms were frequent within the interstitial spaces between barnacles.
Several small soft coral colonies were also present on the buoy (Fig. 6.67c).
The mooring rope was also colonised, although sparsely, with barnacles, individual
Desmophyllum polyps, hydroids and small, soft corals.

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Fig. 6.66 Photomosaic of the mooring buoy deployed at Darwin Mounds West.

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Fig. 6.67a, b and c. Close‐up of a barnacles with Desmophyllum sp. (top), Desmophyllum sp. (middle),
and soft coral (bottom).

The following samples were collected from the mooring:four colonies of L. pertusa (Fig. 6.68a and b) in ethanol;
seven individual Desmophyllum sp. polyps (Fig. 6.69a, b and c) in ethanol;
a one‐eighth sub‐sample of the total biofouling on the buoy (in ethanol);a pseudo‐settlement panel sample (an area of 659 cm2) from the buoy surface, lower half (inethanol); andCruise report No. 66

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

all remaining fouling was frozen for weighing back at NOC.

Fig. 6.68a and b. Example images of L. pertusa on the Darwin Mounds West mooring.
Fig. 6.69a, b and c. Example images of the Desmophyllum sp. polyps on the Darwin Mounds Westmooring.

6.5.1.3. On‐deck observations of the settlement panel mooring from Darwin Mounds East
The buoy was again completely in barnacles (Fig. 6.70). Several urchins, as well as numerous
ophiuroids, were still occupying the buoy following the ascent. The settlement panel 2 m above theseabed was lost during the recovery process. Noteworthy members of the biofouling community
included:






One small colony of L. pertusa was attached to the buoy ‐ the colony was attached to abarnacle plate.
One very small colony of L. pertusa (one polyp colony) attached to the settlement panel but
growing on a barnacle plate. The settlement panel had a significant uncolonised area.
Numerous smaller Desmophyllum sp. polyps were interspersed throughout the barnacle
cover.
Many small orange pectinids were scattered over the barnacle encrustment.
Ophiuroids were abundant across the surface of the buoy (approximately in the low to mid
hundreds).

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

Polychaete worms were frequent within the interstitial spaces between barnacles.
The blue rope attached to the mooring rope was also colonised, although sparsely, withbarnacles, individual Desmophyllum polyps, hydroids and small bivalves.

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A

B

A

B

Fig. 6.70 Biofouling on the two halves of the Darwin Mounds East mooring buoy ‐ the width of the buoy (from point A to point B) is 494 mm.

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The following samples were collected from the mooring:






one colony of L. pertusa (in ethanol);the entire settlement panel (in ethanol);a one‐eighth sub‐sample of the buoy biofouling (in ethanol);a pseudo‐settlement panel sample (an area of 659 cm2) from the buoy surface (in ethanol);andall remaining fouling was frozen for weighing back at NOC.

Laboratory analysis required on return to NOC:

Identification of the species present on each buoy.
Enumeration and weighing of the biofouling species.
Coral samples to be weighed, measured and dispatched for genetic sampling.
Careful examination of the samples for smaller colonies of coral missed on deck.

6.5.2. In situ observations of the settlement panel moorings remaining in place
The mooring remaining in place at Darwin Mounds West was inspected during HyBIS dive 54(16/09/2019). The mooring lacked settlement panels and was estimated to be 4 m in height. The plateanchor was not colonised but the mooring rope was colonised by hydroids and some barnacles. The
buoy was completely covered in feeding barnacles (Fig. 6.71) and looked superficially the same as therecovered buoy. A possible Lophelia pertusa colony was also apparent on the buoy. Additional taxa on
the buoy included sea anemones and large tufts of hydroid.
The mooring remaining in place at Darwin Mounds East was inspected during HyBIS dive 56(18/09/2019). The mooring lacked settlement panels and was estimated to be 4.5 m in height. The
plate anchor was surrounded by debris from the mooring (probably detached barnacles). One of thedetached settlement panels could be seen resting against the anchor and appeared to be colonisedby barnacles. A basket star (Gorgonocephalus sp.) was attached to the bottom of the mooring rope.
The rest of the mooring rope was colonised by a small number of barnacles, hydroids and a Venus fly
trap anemone (Phelliactis sp.). The buoy was again completely covered in barnacles (Fig. 6.72). Basedon a superficial inspection of the camera footage, no hard corals were apparent on the buoy.
Unfortunately, the video recording of this buoy was lost – only the Scorpio downward pictures wererecorded.

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Fig. 6.71 Scorpio downward photographs of the Darwin Mounds West settlement buoy that remainedin‐place. The red box highlights a possible Lophelia colony. The blue box surrounds a sea anemone. The
yellow box shows an area of filtering barnacles. The green box encompasses large tufts of hydroid.

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Fig. 6.72 Scorpio downward photographs of the Darwin Mounds East settlement buoy that remainedin place. The yellow box shows an area of filtering barnacles. The green boxes encompass large tufts
of hydroid.

6.5.3. Initial impressions of the fouling growth present at both sites
 More hard coral colonies were present on the moorings located in Darwin Mounds West whencompared with Darwin Mounds East. Western moorings were also shorter than those in the
East.
 The biofouling community consisted of attached and, interestingly, many large and numerous
mobile epifaunal species ‐ it is likely that these species also settled on the buoy rather thanmigrated up the mooring rope.
 Coral colonies were typically growing on barnacle plates suggesting the surviving colonies
settled sometime after the barnacles i.e. less than 8 years ago.
 Coral growth is moderately rapid in the West with one colony having grown close to 10 cm inlength in 8 years (or less as is more likely considering corals were attached to barnacle plates).
 It is possible that the high abundance of mobile epifauna is maintained by large quantities ofpseudo‐faeces produced by the barnacles and bivalves.

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

It is not clear whether the coral settlement and growth on the buoys is enhanced by: (i) theelevation above the seabed, and consequently an increase in current speed and foodavailability; (ii) isolation from seafloor predators and sedimentary processes (burial andscour); and/or (iii) the reduction of taphonomically induced mortalities of settling larvae on
cleaner buoy surfaces.

6.5.4. Deployment of new settlement experiment
Following the successful recovery of the JC060 moorings, and the unexpectedly high colonisation
rates, it was decided that further settlement experiments should be carried out to investigate
following questions:Given the high colonisation in eight years, what is the level of settlement/colonisation after 1
year?
Do corals settle preferentially on barnacle plates rather than directly on the plastic shells of
the marker buoys?
What is the effect of height above the seabed?

In order to obtain some pilot data to answer these questions, the plastic shells of the mooring werecleaned, and attached at two different heights to the oceanographic mooring that was deployed in
the Eastern Darwin Mounds (see Section 7.5). The inside of the shells was cleaned with a ligh soap,
while the outside was just scraped clean, leaving some biological residue from the barnacles as
biological settlement surface.

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6.6. Water column study from CTDs, ADCP, mooring, sediment trap and lander(Sam Jones, Brian Bett)
Oceanographic measurements during DY108/109 consisted of CTD casts (with LADCP), continuous
measurements with the ship‐board ADCPs, a mooring deployment and the attempt to recover &deploy a lander frame with upward‐looking ADCP.
6.6.1. Shipboard ADCP measurements
RRS Discovery is fitted with RD Instruments 75kHz and 150 kHz Ocean Surveyor ADCPs. The
instruments are mounted in the ship’s hull in a forward–aft configuration, approximately 6 m below
the waterline.
Positional and attitude information is provided via a PosMV multi‐receiver GPS attitude sensor.
Discovery now uses UHDAS (University of Hawaii Data Acquisition System), which in turn employs
CODAS (Common Ocean Data Access System database) to construct a dataset of averaged, Earthreferenced ocean velocities. The root folder for the VM‐ADCP data (raw and processed) is in thefollowing folder in the ship’s data archive:
Ship_Fitted_Scientific_Systems\Acoustics\ADCP‐UHDAS.
The UHDAS GUI is used to configure the ADCP and perform velocity mapping to the reference frameof the vessel. Bottom tracking was disabled for the cruise as the work areas were in waters too deepfor it to be effective.
Vessel mounted ADCP data were recorded throughout DY108 with the exception of the long transits
at the beginning and end of the cruise. In general, the ADCP systems worked well throughout thecruise, though suffered from a daily mid‐water column reduction in signal strength which might belinked to zooplankton diurnal vertical migration. As a rule of thumb, the 150 kHz instrument has alower range but better resolution than the 75 kHz insrument. Typical ranges achieved by the
instruments were as follows:
OS75 broadband: 180 m
OS75 narrowband: 400 m
OS150 broadband: 100 m
OS150 narrowband: 180 m
RDI OS150 Setup
Narrowband Mode:
NB Number of Bins:
NB Bin length (m):NB Blanking (m):Broadband mode:
BB Number of Bins:
BB Bin length (m):BB Blanking (m):Bottom Tracking:
BT Max Depth (m):TP min ping time (s):Trigger in,out [,timeout]:

Cruise report No. 66

ON
40
8.0
4.0
ON
80
4.0
4.0
OFF
500.0
01.10
0,0

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RDI OS75 Setup
Narrowband Mode:
NB Number of Bins:
NB Bin length (m):NB Blanking (m):Broadband mode:
BB Number of Bins:
BB Bin length (m):BB Blanking (m):Bottom Tracking:
BT Max Depth (m):TP min ping time (s):Trigger in,out [,timeout]:

ON
60
16.0
8.0
ON
45
8.0
8.0
OFF
1000.001.80
0,0Accessing the processed data in the UHDAS file structure
The VM‐ADCP data processed by UHDAS are automatally output and stored in the ship’s archive in thefolder:
Ship_Fitted_Scientific_Systems\Acoustics\ADCP‐UHDAS\proc\os75nb\contour (e.g. for 75 kHz
narrowband data).
This contains temporally averaged and gridded data, which has been referenced to Earth coordinates(ship
velocities
removed).
The
UHDAS
user’sguide(https://currents.soest.hawaii.edu/docs/adcp_doc/adcp_data/adcp_access/READING/MATLAB/GET
MAT/index.html) provides the following information for reading these data files into Matlab:
1. You will probably want the matlab program load_getmat.m (available for download from the
webpage above).
2. Identify the location of the files generated by getmat.m. For example, a modern UHDAS installation
writes files in contour/allbins_*.mat. You can see the live processing directory and access theallbins*.mat files by looking at the shared data directory and following the example in the next step.
3. If the location of the getmat output is uhdas_data/km1001c/proc/os38nb/contour then load thefiles with matlab as follows:data = load_getmat('uhdas_data/km1001c/proc/os38nb/contour/allbins_');% DO apply the editing mask:
u = data.u .* data.nanmask;
v = data.v .* data.nanmask;

4. Variable names are documented with “help load_getmat”.

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Example data plots

Fig. 6.73 U (eastward) and V (northward) currents recorded by the 75 kHz vessel‐mounted ADCP in
narrowband mode. The time interval shown approximately covers the occupation of the Darwin
Mounts study areas. Note the period between the 14th and 16th September when the ship moved to an
anchorage in the Outer Hebrides to avoid a storm.

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Fig. 6.74 Stick vectors of temporally averaged currents by depth for the two study sites in the Darwin
Mounds region. Note that the stick vectors only extend to the range of the ADCP, not the full watercolumn. Each location average is constructed from numerous occupations between 11th Septemberand 26th September. Data from 75 kHz vessel‐mounted ADCP in narrowband mode.

6.6.2. Water column structure in the Darwin Mounds
Three CTD profiles were collected in the Darwin Mound area (Fig. 6.75), in order to obtain soundvelocity profiles for the acoustic systems in addition to information about the environmental
conditions around the coral mounds. The lower portion of the profiles is plotted in Fig. 6.76, and thewater column characteristics are summarised in Table 6.15.

Fig. 6.75 CTD locations in Darwin Mounts study region during DY108
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Fig. 6.75 Plots of downcast CTD profiles for the three casts made in the Darwin Mounds area
(West Field, DY108‐006, 017; East Field, DY108‐047)

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Table 6.15 Benthic boundary layer water properties as determined by CTD deployments. The data
presented are statistical summaries of the downcast data logged while the CTD package was at analtitude of < 20 metres above bottom.

DY108‐006

DY108‐017

DY108‐047

Variable

Statistic

West Field

West Field

East Field

Pressure (db)Median

958.4

966.6

1027.8

Altitude (m)Temperature (ITS‐90, °C)

Salinity (PSU)

Oxygen (µmol kg‐1)

Fluorescence (Chl, µg L‐1) × 10‐3

Beam Transmission (%)

Turbidity (m‐1 sr‐1) × 10‐4Interquartile range

1.3

1.4

1.1

Minimum

955.1

959.5

1020.6

Maximum

960.2

969.0

1030.0Median

14.61

9.45

10.36

Interquartile range

0.59

0.65

0.53

Minimum

13.84

8.31

9.50

Maximum

19.47

19.15

19.71

Median

7.631

7.757

7.403

Interquartile range

0.003

0.003

0.010

Minimum

7.624

7.753

7.380

Maximum

7.647

7.776

7.435

Median35.188635.1938

35.1783

Interquartile range

0.00030.00030.0006

Minimum

35.188135.1933

35.1759

Maximum

35.189635.1948

35.1803

Median

229.6

229.8

228.3

Interquartile range

0.3

0.3

0.3

Minimum

228.9

229.2

227.7

Maximum

230.1

230.4

229.0

Median

5.3

6.4

8.1

Interquartile range

4.1

3.8

4.7

Minimum

‐2.1

‐1.5

‐3.4

Maximum

13.7

13.7

19.2

Median

98.77

98.70

98.06

Interquartile range

0.03

0.06

0.06

Minimum

98.30

97.33

97.23

Maximum

98.84

98.82

98.16

Median

3.15

3.73

4.75

Interquartile range

0.29

0.50

0.71

Minimum

2.83

3.07

3.76

Maximum

4.76

5.54

15.97

Plotting CTD data in T‐S space shows a nearly straight mixing line between North Atlantic Water(carried in the European Slope Current) and Modified North Atlantic Water or some other mid‐depth
water mass in the Faroe‐Shetland Channel (Fig. 6.76). This would seem to indicate some residual
effect from sporadic overflow episodes, perhaps the overflowed water remains stagnant in the centreof the basin and mixes away gradually. An alternative explanation, although unlikely, would be that
there is some southern deep‐water source which could explain this.

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Fig. 6.76 Temperature–salinity plot for the three CTD stations in the Darwin Mounts region. The T‐Sproperties of local water masses are overlaid, based on the definitions by Johnson et al. (2013) and
McKenna et al. (2016). See map in Fig. 6.77 for a schematic of the pathways of the water masses
highlighted.

Apart from the CTDs in the Darwin Mound area, the first CTD cast (DY108‐001) was performed justnext to the location of one of the large moorings of the CLASS Ellett Line (see next section), two more
CTD casts were taken between the ADCP lander and this mooring (DY108‐004), and two 24‐hour yoyo
CTDs were carried out in a submarine canyon on the Irish Rockall Margin, for the BLT‐Recipes project(DY108‐058 to 060). All CTD casts carried the LADCP (see section 7.5 for technical details). During thesecond 24‐hour yoyo CTD, the instrument frame touched the seabed, and the CTD had to be broughton board for an hour to be checked over. The system turned out to be unharmed, and the yoyo CTD
was continued. Initial data visualisation indicated unusual water column structures with clearly
different water masses.

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Fig. 6.77 Flow pathways of water masses referred to in Figure 2. WNAW = Western North Atlantic
central Water, carried in North Atlantic Current; ENAW = Eastern North Atlantic Water, enters Rockall
Trough from south; NAW = North Atlantic Water, carried from Bay of Biscay region in Shelf edge
current; MNAW = Modified North Atlantic Water, circulates at mid depth in Faroe‐Shetland Channel.

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Fig. 6.78 Zoomed portion of temperature‐salinity plot, showing only the water deeper than 800 m.

6.6.3. OSNAP ADCP lander
6.6.3.1. Attempted AL500 lander pickup
We began pinging near expected location and planned to follow a spiral search pattern outward which
would allow some coverage up and down slope in the limited time available. We arrived two km southof RTADCP1 on the 750 m contour on 9 September, and began pinging at 05:19. Response was almost
immediate, initially ranging at 2166 m. Subsequent ranging placed it in the same location it was
deployed, minimum range from the drop keel was 741 m. We then held station for two hours to allow
a fishing trawler to leave the area. Both releases were successfully fired at 07:20 but caused no change
in range. We moved off to conduct a CTD at EB1 (35 minutes steam) and returned around 13:00.
Further ranging to the releases demonstrated that the lander hadn’t moved during this interval.
An attempt was made to launch the NOC HyBIS system with cameras to assess the state and positionof the lander on the seabed. However, lowering was aborted at 400 m due to a loss of all telemetryon the HyBIS which was later traced to an onboard power failure. There was no time to repair the
HyBIS that day, so the investigation was aborted.

6.6.3.2. AL500 lander deployment and retrieval
The new lander assembly to be deployed on DY108 was comprised of a new concrete base suppliedby the AL500 manufacturer, refurbished buoyancy and gimbal assembly (also built by the AL500
manufacturer) and a new aluminium pad built by an external fabricator.
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The onboard acoustic release was armed, tightened and checked, then the buoyancy unit wasassembled onto the structure on 8th September. We decided to program and power‐on the ADCP at
5 pm on the 8th September due to a combination of calm sea, dry weather and lack of deck activity.
This meant that programming and connecting the battery and dummy comms plug was done without
time pressure. The ADCP was also set to flash for 24 hours to ensure it was sampling at the rate
expected.
The ADCP battery cable has male connectors at both ends and there is a significant risk of a short‐circuit on the metal frame if it is first connected to the battery and left loose. We found that the cable
can be first connected to the gimballed ADCP by chocking the gimbal up and reaching inside, thenconnected to the battery by reaching into the Iridium beacon hole on the buoyancy, thereby
eliminating short‐circuit risk. Arrows were painted on the buoyancy pointing to the lifting eyes which
tend to sit underwater during recovery. The protective dome for the ADCP was missing on this lander,
so we hoped to use the dome from the recovered lander. In the event, there was no recovery so we
decided to proceed with the exposed ADCP.
The deployment method was similar to that used in previous AL500 deployments, with glass spheres
fitted above the lifting gear to keep the bridle under tension on the seabed prior to release (Fig. 6.79).
The lander was lifted off the deck at 15:42 and quickly manoeuvred over the water. It was in the waterat 15:45. Lowering was briefly delayed as a handling line had become wrapped around the lander. It
was then lowered gently as the ship’s heave was creating slack in the winch cables. At about 15:50 the
onboard lander release mechanism failed, allowing the buoyancy to prematurely separate and drift
away. Reviewing a video of the deployment shows that it survived numerous heaves of the ship before
it failed, but that this probably contributed to the release failure.

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Fig. 6.79 Prior to deployment, showing layout of lifting bridles.

The concrete base (which would not normally have to be lifted back on deck) was manoeuvred
carefully out of the water and secured on both sides to stop it swinging (Fig. 6.80). It wasbBack on
deck at 16:13. The lander package was brought alongside the ship and hooked with a telescopic poleon one of its lifting eyes. It was lifted by one eye and was back on deck at 16:47.

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Fig. 6.80 Retrieval of the buoyancy and aluminium pan

A preliminary investigation suggests that nothing failed structurally in the release mechanism. It
appears that a combination of play in the release mechanism, and an altered latch geometry, which
was necessitated by differences between the new aluminium pan and the manufacturer’s version,
made the latch less secure (Fig. 6.81). It is likely that it would hold the static force of the buoyancy
but that the dynamic snatching forces on deployment contributed to its failure to stay latched under
tension.

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Fig. 6.81 Armed release from side

6.6.3.3. ADCP lander HyBIS survey on 26/09/2019
Towards the end of DY108 there was an opportunity to return to the ADCP lander site and conduct asurvey with the HyBIS to try to ascertain the cause of its failure to surface. The lander was locatedrelatively quickly using the HyBIS’s forward scanning sonar less than 10 m away from the predicted
location based on its deployment triangulation conducted on AR30 in 2018.
The camera survey revealed extensive trawl damage, with the ADCP and its gimbal separated fromthe lander’s structure and lying beside it, but with the ADCP battery cable still connected (Figs. 6.82 &
6.83). This damage alone would not have prevented the lander from surfacing; however, the main
structure was also buried beneath a thick layer of sediment. This presumably was heavy enough tocounteract the ~200 kg of positive buoyancy supplied by the syntactic foam and keep the lander on
the seabed. It is possible that future trawl activity will cause the lander to release and float to thesurface as both acoustic releases successfully fired. The Iridium system and light may still befunctional, but the ADCP and its acquired data will almost certainly be lost, as the weak point in thebattery cable (the plastic connector at its termination) will likely fail on the ascent or shortly after.

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Fig. 6.82 ADCP lander deployed on AR30 cruise in 2018. Imaged by HyBIS in September 2019 after it
failed to surface and was found to have been damaged and partially buried by trawl activity.

Fig. 6.83 Close‐up of damaged gimbal and ADCP head

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6.6.4. Darwin Mounds long‐term mooring (DY108‐048)
Recovery information
Position:
Water depth:
Release:Last bottle closes:
Instrumentation:
Samples:

59° 51.672´ N 007° 02.631´ W (triangulated)
1028 m (corrected)
s/n 2330, ARM 1B89, REL 1B55
12:00 6 October 2020
ADCP, 21‐bottle sediment trap, 2 × MicroCAT
21 × formaldehyde preserved (caps with NOC MG); 3 × hard hatcolonization surfaces (e.g. Teledyne Benthos 17” standard ribbed single
shell) – containers / preservatives / protocols needed

General mooring arrangement
The mooring comprised a pick‐up float (12” glass), buoyancy pack (3 × 17” glass), MicroCAT, 44”
syntactic sphere carrying: light, argos, and downward ADCP, 21‐bottle sediment trap, 2 × colonization
hard hat, MicroCAT, 1 × colonization hard hat, acoustic release, and 1000 kg chain clump anchor (Fig.
6.84).
The mooring was deployed buoyancy first, towed to nominal position and let go. The achieved locationof the mooring was estimated by triangulation from three points c. 0.5 nm from the intended target
location. The intention is for the mooring to be in place for ~one year.
Sediment trap preserving fluid19 L deep seawater (CTD DY108‐001; 1000 m)
100 g NaCl
1 L c. 38% formaldehyde solution
5 g sodium tetraborate

The preserving fluid was made up as per the recipe above; seawater and salt were mixed and left fora few days; formaldehyde and borax were mixed and left for a few days; hypersaline seawater andbuffered formaldehyde were mixed and left a few days. Trap bottles were filled near‐full and fitted tothe carousel and left a couple of days (aided clearance of bubbles), then topped‐up using the trap “fillprogram”. Archive sample retained as blank (NOC MG).
Sediment trap programming
The sediment trap carousel system was programmed (Table 6.16) to rotate one unit every 18‐daysfrom 12:00 UTC 25 September 2019, i.e. first bottle opens at that time. The last bottle is scheduled toclose at 12:00 UTC 6 October 2020. Trap programming and schedule were as follows:

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Fig. 6.84 Darwin Mounds long‐term mooring as deployed (DY108‐048)

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Table 6.16 Sediment trap schedule asprogrammed

Keystroke log
Is the rotator aligned to theopen hole (Yes/No) [N] ? y

ActionClock reads 09/22/2019 15:29:57
Change time & date (Yes/No) [N] ? n0Existing deployment data file will beerased. Continue (Yes/No) [N] ? y1

Enter new deployment schedule (Yes/No) [N]? n2

Schedule Verification

3

Event
Event
Event
Event
Event
Event
Event
Event
Event
Event
Event
Event
Event
Event
Event
Event
Event
Event
Event
Event
Event
Event

1 of
2 of
3 of
4 of
5 of
6 of
7 of
8 of
9 of
10 of
11 of
12 of
13 of
14 of
15 of
16 of
17 of
18 of
19 of
20 of
21 of
22 of

22 = 09/24/2019 12:00:00
22 = 10/12/2019 12:00:00
22 = 10/30/2019 12:00:00
22 = 11/17/2019 12:00:00
22 = 12/05/2019 12:00:00
22 = 12/23/2019 12:00:00
22 = 01/10/2020 12:00:00
22 = 01/28/2020 12:00:00
22 = 02/15/2020 12:00:00
22 = 03/04/2020 12:00:00
22 = 03/22/2020 12:00:00
22 = 04/09/2020 12:00:00
22 = 04/27/2020 12:00:00
22 = 05/15/2020 12:00:00
22 = 06/02/2020 12:00:00
22 = 06/20/2020 12:00:00
22 = 07/08/2020 12:00:00
22 = 07/26/2020 12:00:00
22 = 08/13/2020 12:00:00
22 = 08/31/2020 12:00:00
22 = 09/18/2020 12:00:00
22 = 10/06/2020 12:00:00

4
5
6
7
8
9
10
11
12

Modify an event (Yes/No) [N] ? nCurrent Header reads:
DY108

13

Do you want a different header (Yes/No)[N] ? n14

System status:

15

09/22/2019 15:31:32 18.7 Vb 18 øCaligned

16
Caution:

Deployment will overwrite the
EEPROM data backup cache.

17

Proceed with the deployment (Yes/No)? y>>> Remove communication cable and <<<>>> attach dummy plug. <<<>>> Sediment trap is ready to deploy. <<<<09/22/2019 15:31:46> Waiting for Event 01
of 22 @ 09/24/2019 12:00:00
09/22/2019 15:31:48 Sleeping . . .

18
19
20
21

UK Date24/09/2019
12:00
12/10/2019
12:00
30/10/2019
12:00
17/11/2019
12:00
05/12/2019
12:00
23/12/2019
12:00
10/01/2020
12:00
28/01/2020
12:00
15/02/2020
12:00
04/03/2020
12:00
22/03/2020
12:00
09/04/2020
12:00
27/04/2020
12:00
15/05/2020
12:00
02/06/2020
12:00
20/06/2020
12:00
08/07/2020
12:00
26/07/2020
12:00
13/08/2020
12:00
31/08/2020
12:00
18/09/2020
12:00
06/10/2020
12:00

US Date09/24/2019
12:00
10/12/2019
12:00
10/30/2019
12:00
11/17/2019
12:00
12/05/2019
12:00
12/23/2019
12:00
01/10/2020
12:00
01/28/2020
12:00
02/15/2020
12:00
03/04/2020
12:00
03/22/2020
12:00
04/09/2020
12:00
04/27/2020
12:00
05/15/2020
12:00
06/02/2020
12:00
06/20/2020
12:00
07/08/2020
12:00
07/26/2020
12:00
08/13/2020
12:00
08/31/2020
12:00
09/18/2020
12:00
10/06/2020
12:00(Action 0 opens bottle 1, Action 1 closes bottle
1and opens bottle 2 etc. etc.)

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Acoustic Doppler current profiler set‐up
A 600 kHz ADCP in downward‐looking orientation was set‐up to the following specification:






Duration: 365 days
Ensemble interval: 00:01:30
Ping interval: 00:00:05
Pings per ensemble: 10
Depth cell size: 1 m (30 m range)

MicroCAT sensors
The mooring was fitted with two MicroCATS (Sea‐Bird Scientific SBE 37‐SM) carrying temperature,
conductivity, and pressure sensors. One MicroCAT (s/n 12456) was located at c. 79 mab (949 m) andthe other (s/n 124558) was located at c. 4 mab (1024 m). The MicroCATs, sampling at 10‐second
intervals, were tested on CTD deployment DY108‐047, carried out in the near vicinity of the intended
mooring location, immediately prior to the mooring deployment (Table 6.17). During the up‐cast of
the CTD, 5‐minute stops were made at four depths (1014, 945, 101, and 36 m) to provide cross‐calibration data. Following standard processing, the CTD and MicroCAT data were summarized tomedian and 95% non‐parametric confidence intervals for the periods of the stops. The resultant dataand plots (Fig. 6.85) suggested that both MicroCATs were performing well.
For the mooring deployment (DY108‐048), MicroCAT sampling interval was set to 15‐minutes.

Colonization panels
The mooring was fitted with three colonization panels, two located at c. 11 mab (1017 m) and one
located at c. 4 mab (1024 m). Each panel is a single shell of a Teledyne Benthos 17” standard ribbed‘hard hat’. These shells were recovered during the cruise as marker buoy originally emplaced during
RRS James Cook cruise 060 (see original cruise report, and section 6.5 in this report). The heavy
biofouling was roughly cleaned from the outer surface of the shell, and the essentially clean innersurfaces given a basic wash prior to their redeployment on the mooring (DY108‐048).

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Table 6.17 CTD and Microcat data from “calibration stops” on up cast of DY108‐047; median value (95% CI) during stop
CTD hand log
Depth (m)CTD data
Time

Temp

Sal

Con

Pressure (db)Temperature (ITS‐90, °C)

Conductivity (mS cm‐1)

Salinity (PSU)

1

36 m

06:14

11.9

35.27940.16436.3(36.2, 36.3)

11.8857(11.8850, 11.8862)

40.1303(40.1297, 40.1306)

35.2204(35.2204, 35.2204)

2

101 m

06:06

10

35.32538.469102.1(102.1, 102.1)

10.0232(10.0232, 10.0234)

38.4734(38.4733, 38.4735)

35.3229(35.3228, 35.3229)

3

945 m

05:43

7.9

35.2

36.71

956.0

(956.0, 956.0)

7.8755(7.8754, 7.8757)

36.7056(36.7055, 36.7058)

35.1988(35.1988, 35.1988)

41014 m05:34

7.7

35.17936.2791027.9(1027.9, 1028.0)

7.4029(7.4027, 7.4029)

36.2773(36.2772, 36.2774)

35.1783(35.1782, 35.1783)

Depth (m)Microcat s/n 12456

Microcat s/n 12458

Cruise report No. 66

34.2(34.0, 34.5)

11.8871(11.8836, 11.8960)

40.1296(40.1257, 40.1375)

35.2180(35.2175, 35.2187)

99.9(99.8, 100.2)

10.0242(10.0209, 10.0266)

38.4705(38.4684, 38.4737)

35.3203(35.3200, 35.3207)

943.4(943.2, 943.5)

7.8767(7.8746, 7.8798)

36.7033(36.7018, 36.7073)

35.1964(35.1962, 35.1967)

1014.3(1014.1, 1014.6)

7.4033(7.3993, 7.4054)

36.2743(36.2711, 36.2759)

35.1752(35.1750, 35.1755)

34.6(34.3, 34.8)

11.8853(11.8836, 11.8947)

40.1306(40.1286, 40.1397)

35.2209(35.2203, 35.2214)

99.8(99.7, 100.0)

10.0263(10.0236, 10.0294)

38.4758(38.4736, 38.4778)

35.3227(35.3224, 35.3235)

943.2(942.9, 943.6)

7.8789(7.8762, 7.8839)

36.7067(36.7050, 36.7129)

35.1987(35.1984, 35.1988)

1014.3(1014.1, 1014.7)

7.4054(7.4014, 7.4087)

36.2782(36.2752, 36.2820)

35.1778(35.1776, 35.1780)

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Microcat
s/n 12456

CTD vs Microcat temperature

CTD vs Microcat conductivity

CTD vs Microcat salinity

CTD pressure vs Microcat depth

CTD vs Microcat temperature

CTD vs Microcat conductivity

CTD vs Microcat salinity

Microcats/n 12458

CTD pressure vs Microcat depth

Fig. 6.85 Cross‐calibrations of CTD and MicroCAT data

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6.7. Outreach activities (Larissa Macedo, Loïc Van Audenhaege)
During the DY108/109 cruise, outreach practice was performed through social media. The scientists
were well engaged with content sharing and media coverage. Information about daily activities on thecruise was shared via Twitter and the blog page on the following addresses:‐‐@CLASS_UKRI ‐ (https://twitter.com/CLASS_UKRI)
CLASS blog ‐ (https://projects.noc.ac.uk/class/blog)

Larissa Macedo and Loïc Van Audenhaege were responsible for tweeting and posting on the blog,
under the supervision of Veerle Huvenne.
The account @CLASS_UKRI tweeted an average of two tweets/day. All content was linked to twitter
accounts and hashtags of the research bodies and partners i.e. SAMS (@ScotMarineInst), JNCC(@JNCC_UK), University of Southampton (@unisouthampton), University of Edinburgh(@EdinburghUni), NOC (@NOCnews) and BioCam (#BioCam) and the study site #Darwinmounds.
Usually, tweets were posted with a type of visual content which included images and videos of theequipment, scientists in action and the findings from HyBIS HD camera. The scientists on board werealso active on media sharing. Around eight scientists tweeted from their personal accounts making
use of the aforementioned names and hashtags.

The statistical data collected with Twitter Analytics shows that the content shared on @CLASS_UKRI
account earned around 57.1K impressions since the start of the cruise. The number of profile visits
and impressions has increased by 56.3% and 360.3%, respectively (Fig. 6.86):

Fig. 6.86 Data from 01/10/2019. Source: Twitter

Until the 1st of October, 2019, our top tweets earned around 4.990 impressions (Fig. 6.87):

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Fig. 6.87 Data from 01/10/2019. Source: Twitter

As for the blog, there was a commitment to post at least twice a week. The posts covered different
activities that were carried out during the cruise. Usually, it contained information about the Darwin
Mounds, equipment, weather forecast, methods, and general research activities. The aim was to givean idea about daily research routine and life at sea to compose a story related coherently by thedifferent posts. All posts were followed by visual content within the context of the blog.
Since the start of the DY108/09 cruise, the website statistics showed an increase in new users by
66,5%. Around 44.5% of the users are concentrated in the UK and 29% are from the USA. The blog hasreached other countries such as France (6.63%), Belgium (3.37%), Canada, Australia, Denmark, Spain(Fig. 6.88).

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Fig. 6.88 Website interaction statistics for the CLASS project cruise website during the second week of
the cruise

The overall results of outreach activities were positive. As can be seen from the statistical data, thesocial media engagement was considered high and the actions attracted new users and impressions
to the project's results.
The expedition story had also an impact on the news media as the BBC wrote five press articles forthe section “UK/Scotland/Highlands & Islands” and the Times in Scotland wrote one article. See links
below:●●●●

https://www.bbc.co.uk/news/uk‐scotland‐highlands‐islands‐49606937
https://www.bbc.co.uk/news/uk‐scotland‐highlands‐islands‐49727181
https://www.bbc.co.uk/news/uk‐scotland‐highlands‐islands‐49753440(https://www.thetimes.co.uk/article/protected‐coral‐reef‐is‐blighted‐by‐plastic‐waste‐03k85j63v

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In addition, several posts contained an hyperlink to a 3D model of some organism (e.g. Desmophyllum
dianthus) and scientific features (e.g. the buoy recovered). High‐resolution 3D models are easy tomake and do not require powerful hardware (phone`s camera and a basic computer, software:
Meshroom (opensource) or Agisoft). SketchFab was used for 3D data visualization. This outreach tool
is in our opinion a good way to enable people to interact with our scientific work and to show what
we do for a non‐specialised audience.

Outreach recommendation for future expeditions:●
Before an expedition, we recommend that most of the scientific accounts post an update
regarding the preparation of the cruise by uploading teaser‐like posts. This would help to already build
up a more solid and earlier audience prior to the expedition.
●
Twitter can spread tweets very quickly but, it is mainly used by a specific public. The use of
Instagram and Facebook could be a way to reach better a “more general” audience. Facebook could
be a way to update people with more detailed stories than Twitter, while Instagram is useful to sharevisual content through the “Story” feature. It is necessary to mention that Instagram does not allow
to share hyperlinks (if account <1000 followers). Finally, the National Oceanography Centre is active
on Instagram and on Facebook and these accounts could be useful to share the project account prior
to the start of the expedition.
●
Finally, as the expedition can be sometimes repetitive, it is necessary to think of plans B interms of outreach (e.g. “How is the life at Sea”, “Who is involved in the running of an expedition (i.e.
focussing on the cooks, technicians, engineers, navigation crew)”). Furthermore, it could be a great
idea to define a more recreative post concept that will be related once a week. For example, a quiz
every Sunday (e.g. “What is this animal?”) or a “Fun‐fact” Sunday post, etc.

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7. EQUIPMENT & SAMPLING REPORTS
7.1. Autosub6000 Cruise Report
Operational Team : Phil Bagley, Rachel Marlow, Owain Shepherd, Richard Austin‐Berry, Eoin O’Hobain

7.1.1. Autosub 6000 Cruise Summary
The Autosub 6000 was deployed on 7 missions (1 abandoned), providing Sidescan and Biocam survey
data as well as delivering the standard suite of science data throughout (Table 7.1). The Biocam
operated successfully in all but the last deployment where the cable between the Logger tube and the
Biocam appeared to have failed under pressure preventing Autosub UDP data reaching the Biocam.
One mission (M154) was abandoned soon after deployment. The Phins unit within the Autosub Inertia
Navigation System hung and was not responding to motion or heading changes. The Autosub wasrecovered back to deck successfully. During M155, after successfully completing a 90km side scansurvey the ADCP (used for bottom tracking) failed just after the start of Biocam element of the mission.
The vehicle ascended to the safe depth and the mission was aborted. The ADCP unit was replaced
and the vehicle successfully operated during the following final mission.

Table 7.1 Overview of Autosub missions for DY108/109
Mission
M150
M151
M152
M153
M154
M155
M156
Total

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Survey Time
4 hrs 36 mins
23 hrs 43 mins
23 hrs 59 mins
24 hrs 55 mins
(mission abandoned)
25 hrs 1 min
26 hrs 8 mins
5 days 21 hrs 40 mins

Distance Travelled
12.7 km
93.5 km90.3 km90.2 km‐
97 km
92.9 km
476.6 kmMaximum Depth
206.6 m968.3 m965.8 m1043.7 m‐
1063.3 m
952.8 m‐Page 134 of 224

Fig. 7. 1 Owain & Richard recovering the Autosub after Mission M156

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Mission 150
The AUV was launched and dived successfully. The AUV was monitored via the Ships USBL and the
Linkquest throughout the mission, a navigation offset was not sent and the vehicle sent on its way.
The vehicle surfaced a little ahead of schedule in the expected location and was recovered back on
deck without incident in increasingly freshening winds. Initial analysis of data indicated a successful
mission.
Mission 151
The AUV was launched and dived successfully. The AUV was monitored via the Ships USBL at the startof the dive. We were unable to set the mission navigation offset due to poor Linquest communication.
The navigational offset at the start was (Autosub was located):

459m south of the starting waypoint
265m West of the starting waypoint.

The mission was completed as expected. The vehicle surfaced a little ahead of schedule in the
expected location. Due to higher sea state than forecast we did not immediately recovery the Autosub
and stood by for approximately 4 hours. The weather conditions had improved slightly but conditions
were still difficult for the recovery. Autosub was recovered back on deck without incident due the skillof Owain and Richard, the officers on the Bridge and the deck crew. Initial analysis of data indicated a
successful mission, with embedded Edgetech navigational data and good Biocam imagery. To improvelighting for future missions the Biocam team may increase the intensity of the LED flashes.
Mission 152
Dense Grid Biocam survey of Western Darwin Mounds. Test New Biocam lighting configurations. The
vehicle successfully dived, however the USBL stopped working during the descent. The Linquest
acoustic telemetry also failed to communicate with the vehicle once the vehicle reduced its pitch as it
approached the sea floor. This is similar to the situation on M151. Biocam work successfully. LED
drivers were modified to run at higher voltage, creating a brighter flash.
Mission 153
AUV successfully dived and was followed on the Ships USBL and the LinkQuest Fish until the AUV
moved into ‘WaitAtAlt’ mode where the LinkQuest communication dropped out. Ship repositioned
over vehicle and LinkQuest Fish was set to high power, this enabled intermittent comms with AUV
meaning it was possible to send the required navigation offset. The AUV then continued the mission
and surfaced about 90 minutes later than expected. Initial analysis suggests that a number of surveylines overran the expected duration and timed out potentially due to strong seabed currents. The
data also shows that the vehicle hit the seabed although there is no visible damage to the AUV. The
AUV was successfully recovered.
Mission 154
The vehicle was successfully launched but once in the water no heading change was observed in the
mission commander. The vehicle was recovered before starting the mission. Later analysis showed
the Phins unit within the Autosub’s Inertial Navigation System had hung, and vehicle motion was not
being measured or recorded. This situation may occur when the Phins does not successfully complete
it’s alignment phase. Alignment has two phases:
Course alignment when the Phins unit should be kept as still as possible
Fine alignment when the Phins should experience moderate motion.

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This can be difficult to achieve on a ship and deployment procedures were updated to confirm correct
Phins operation before relese into the water.
Mission 155
Successful Edge tech mission. However, just after the Biocam section of the dive started the Autosub
lost bottom lock and dived and hit the seabed. It aborted the mission and ascended to near the safe
depth of 160m (note a safe depth of 100m was programmed, unclear why the Autosub did not achieve
this depth. However strong surface currents were present at the time and may have influenced
Autosub dynamic performance ). The mission was aborted via the Linquest system on the acoustic fish
and the vehicle surfaced 50m from the ship. Recovered on board safely. Later analysis showed theAutosub lost bottom lock because the ADCP had failed. The Autosub then dived to try to reacquire theseabed, causing the collision with the seabed. Post mission the ADCP was removed and bench tested
where it was conformed both beams 2 & 4 were no longer working.
Mission 156
The new ADCP was tested successfully by performing a dive to 900m to obtain DVL bottom lock andrun two test lines. The vehicle then ascended back to the surface again and paused where data was
offloaded to check ADCP performance. All appeared correct and so the vehicle was sent on theremaining Biocam mission. The vehicle performed correctly and we saw a better altitude tracking
performance than on earlier dives (Fig. 7.2). The vehicle surfaced as expected and was recovered
successfully under demanding conditions. The Biocam did not collect any data. Initial analysis suggests
the cable between the Biocam and the logger failing under pressure at 900m at the start of the Biocam
mission. Then working again at 300m on the ascent after the Biocam mission. Although power was
still being supplied the Biocam did not receive any UDP messages from Autosub. Post mission analysisof the Logger tube data showed UDP messages around the Autosub vehicle were working as normal.
Therefore, the cable between the Biocam and the logger is suspect.

Fig. 7.2 Autosub bottom tracking (Track at Altitude command) during M156

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7.1.2. AUV Standard Sensor Configuration

Fig. 7.3 Autosub standard configuration

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7.1.3. AUV Biocam Configuration

Fig. 7.4 Adjusted Autosub configuration to accommodate the BioCam system

7.1.4. Mission M150 Summary

Campaign: DY108/9

Operating Area

: Mingulay

Mission No.

: M150Objectives
Biocam calibration mission, plus short sidescan sonar lines at end of mission to determine
performance of systems operating together.
Mission Plan
Mission to calibrate the Biocam aboard the Autosub 6000



Initial dive to depth followed by Biocam laser calibration lines at 10m, 9m, 8m, 7m, 6m, and5m.
Followed by a further Biocam data acquisition lines starting at 5m and increasing in altitude
back to 10m in 1m steps.
Final phase of edge Tech survey lines at 15m altitude with Biocam off, then a further Edge
Tech line with Biocam on to determine Autosubs capability to drive both systems anddetermine if any interference was present.

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Table 7.2 Vehicle Configuration and sensors used for M150
Sensors used
1) RDI workhorse ADCP 300kHz
downwards.
2) PHINS INS
3) Seabird 9+ CTD with dual CT sensors
4) EM2040 multi‐beam (not used on
this mission)5) EdgeTech 2200‐M 120‐425kHz sidescan and 2‐16kHz sub‐bottom
profiler (not used on this mission)6) 1 x colour downwards camera andflash (not used on this mission)7) 1 x colour forward camera and flash(not used on this mission)8) Tritech Seaking obstacle avoidancesonar9) Sonardyne G6 USBL Transponder
10) Biocam, two flash panels and two
Class 4 lasers

Sub configuration

1) Rear winglets set at 6º pitched downwards.
2) Autosub 6k recovery line retention systemwith nylon springer lines3) 16.9kg positive buoyancy.
4) 6 x new battery packs.
5) New Autosub6000 launch and recovery
system (LARS)

Table 7.3 Mission Conditions for M150
Start of Mission

End of Mission

Time [logger]

05:18:40 10/09/2019

09:55:35 10/09/2019

Position [GPS]N56:48.096 W7:24.662

N56:48.254 W7:25.045

Sea state

2

3Wind speed

15 knots

Battery Voltage

49.75 Volts

30 knots
48.41 Volts(pack)
Table 7.4 Mission Statistics for M150
Total Mission duration
4 hrs 36 mins

Time on seabedsurveying

2 hrs 21 mins

Avg. descent speed

0.27 m/s

Avg. ascent speed

0.48 m/s

Mean ground speed atbottom0.76 m/s

Distance travelled

12.7 km

Mean motor power

246.7 W

Maximum Depth

206.6 mApproximate usefulvertical images‐

Approximate usefulforward images‐

Useful images are based on survey time between 2m and 4m altitude with a picture rate of 1000 ms.

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The AUV was launched and dived successfully. The AUV was monitored via the Ships USBL and the
Linkquest throughout the mission, a navigation offset was not sent and the vehicle sent on its way.
The vehicle surfaced a little ahead of schedule in the expected location and was recovered back on
deck without incident in increasingly freshening winds.
Initial analysis of data indicated a successful mission.
All systems appeared to operate successfully. Edge tech navigation data not found by Sonarwiz.
However, this was working during test dives in ballast tank prior to cruise. Edge Tech systems appears
to be receiving and interoperating navigational data correctly.
Table 7.5 Sensor Data Quality for M150
EM2040 – not used during this mission
CTD, DO ‐Seaking sonar – Data present, not analysed
Magnetometer – Data present, not analysed
ADCP – Data present (DVL operated correctly)
Side‐Scan Sonar (425kHz) – Data files present, not yet analysed
Side‐Scan Sonar (120kHz) –Sub bottom profiler – Data files present not yet analysed
AESA Cameras – not used during this mission

Fig. 7.5 3D Vehicle track for M150

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Voltage [V]Current [Amps]
Power [W]Fig. 7.6 Mission Power Usage for M150

Fig. 7.7 Current analysis for M150

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Fig. 7.8 Altitude tracking for M150

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7.1.5. Mission M151 Summary

Campaign: DY108/9

Mission No.

Operating Area

: Darwin Mounds (West): M151

Mission Objectives & Description
Repeat 2011 sidescan survey of theWestern Darwin mounds trawl damaged coral field to determine
if the area is improving. At the end of this survey repeat the Biocam calibration runs of M150 (poorvisibility during M150 necessitates re‐running the calibration).
Mission Plan
Sparse Edge Tech grid over eastern Darwin Mounds coral field. !5m altitude, high resolution sidescan survey. Then repeat the Biocam laser calibration survey of M150 i.e.:

Initial dive to depth followed by Biocam laser calibration lines at 10m, 9m, 8m, 7m, 6m, and5m.
Followed by a further Biocam data acquisition lines starting at 5m and increasing in altitude
back to 10m in 1m steps.
Final phase of edge Tech survey lines at 15m altitude with Biocam off, then a further Edge
Tech line with Biocam on to determine Autosubs capability to drive both systems anddetermine if any interference was present.

Table 7.6 Vehicle Configuration and sensors used for M151
Sensors used
11) RDI workhorse ADCP 300kHz
downwards.
12) PHINS INS
13) Seabird 9+ CTD with dual CT sensors14) EM2040 multi‐beam (not used on
this mission)15) EdgeTech 2200‐M 120‐425kHz sidescan and 2‐16kHz sub‐bottom
profiler (not used on this mission)16) 1 x colour downwards camera andflash (not used on this mission)17) 1 x colour forward camera and flash(not used on this mission)18) Tritech Seaking obstacle avoidancesonar19) Sonardyne G6 USBL Transponder
20) Biocam, two flash panels and two
Class 4 lasers

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Sub configuration

6) Rear winglets set at 6º pitched downwards.
7) Autosub 6k recovery line retention systemwith nylon springer lines8) 16.9kg positive buoyancy.
9) 6 x new battery packs.
10) New Autosub6000 launch and recovery
system (LARS)Page 144 of 224

Table 7.7 Mission Conditions for M151
Start of Mission

End of Mission

Time [logger]

12‐Sep‐2019 13:20:11

13‐Sep‐2019 13:02:39

Position [GPS]N59:48.723 W7:20.052

N59:49.207 W7:21.964

Sea state

3

4 to 5Wind speed

20 knots

Battery Voltage

48.0 Volts

30 knots
43.6 Volts(pack)

Table 7.8 Mission Statistics for M151
Total Mission duration
23 hrs 42 mins

Time on seabedsurveying

20 hrs 53 mins

Avg. descent speed

0.32 m/s

Avg. ascent speed

0.43 m/s

Mean ground speed atbottom1.01 m/s

Distance travelled

93.5 km

Mean motor power

320.4 W

Maximum Depth

968.3 mApproximate usefulvertical images‐

Approximate usefulforward images‐

Useful images are based on survey time between 2m and 4m altitude with a picture rate of 1000 ms.
The AUV was launched and dived successfully. The AUV was monitored via the Ships USBL at the startof the dive. We were unable to set the mission navigation offset due to poor Linquest communication.
The navigational offset at the start was (Autosub was located):

459m south of the starting waypoint
265m West of the starting waypoint.

The mission was completed as expected. The vehicle surfaced a little ahead of schedule in the
expected location. Due to higher sea state than forecast we did not immediately recovery the Autosub
and stood by for approximately 4 hours. The weather conditions had improved slightly but conditions
were still difficult for the recovery. Autosub was recovered back on deck without incident.
Initial analysis of data indicated a successful mission, with embedded Edgetech navigational data andgood Biocam imagery. To improve lighting for future missions the Biocam team may increase theintensity of the LED flashes.
All systems appeared to operate successfully. Edge Tech data had embedded navigational data thistime (manually auto record the edge tech during pre‐mission setup). The Biocam appeared tooperate correctly but the image intensity was less than expected. LED intensity will be increased
before the next mission.

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Table 7.9 Sensor Data Quality for M151
EM2040 – not used during this mission
CTD, DO ‐Seaking sonar – Data present, not analysed
Magnetometer – Data present, not analysed
ADCP – Data present (DVL operated correctly)
Side‐Scan Sonar (425kHz) – Data files present, not yet analysed
Side‐Scan Sonar (120kHz) –Sub bottom profiler – Data files present not yet analysed
AESA Cameras – not used during this mission

Fig. 7.9 3D Vehicle track for M151

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Voltage [V]Current [Amps]
Power [W]Fig. 7.10 Mission Power Usage

Fig. 7.11 Current analysis for M151

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Fig. 7.12 Altitude Tracking for M151

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7.1.6. Mission M152 Summary

Campaign: DY108/9

Mission No.

Operating Area

: Darwin Mounds (West): M152

Mission Objectives & Description
Dense Grid Biocam survey of Western Darwin Mounds. Repeating survey of the pervious EdgeTechsurvey. Test New Biocam lighting configurations.
Mission Plan
Biocam Dense grid over the region of the previously Edge Tech surveyed Darwin Mounds (West).
Using Zamboni waypoints to give a spacing of 5 meters between lines.
Table 7.10 Vehicle Configuration and sensors used for M152
Sensors used
21) RDI workhorse ADCP 300kHz
downwards.
22) PHINS INS
23) Seabird 9+ CTD with dual CT sensors24) EM2040 multi‐beam25) EdgeTech 2200‐M 120‐425kHz sidescan and 2‐16kHz sub‐bottom
profiler (not used on this mission)26) 1 x colour downwards camera andflash (not used on this mission)27) 1 x colour forward camera and flash(not used on this mission)28) Tritech Seaking obstacle avoidancesonar29) Sonardyne G6 USBL Transponder
30) Biocam, two flash panels and two
Class 4 lasers

Table 7.11 Mission Conditions for M152
Start of Mission

Sub configuration

11) Rear winglets set at 6º pitched downwards.
12) Autosub 6k recovery line retention systemwith nylon springer lines13) 16.9kg positive buoyancy.
14) 6 x new battery packs.
15) New Autosub6000 launch and recovery
system (LARS)End of Mission

Time [logger]

16‐Sep‐2019 05:46:53

17‐Sep‐2019 05:46:05

Position [GPS]N59:48.860 W7:21.136

N59:48.437 W7:21.504

Sea state33Wind speed

25 knots

Battery Voltage

49.61 [V]20 knots
44.76 V](pack)
Table 7.12 Mission Statistics for M152

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Total Mission duration

23 hrs 59 mins (or86352.2 seconds)

Time on seabedsurveying

19 hrs 8 mins

Avg. descent speed

0.278 m/s

Avg. ascent speed

0.531 m/s

Mean ground speed atbottom0.92 [m/s]Distance travelled

90.3 [km]Mean motor power309.7 [W]

Maximum Depth

965.8 [m]Approximate usefulvertical imagesn/aApproximate usefulforward images

n/a

Useful images are based on survey time between 2m and 4m altitude with a picture rate of 1000 ms.
Table 7.13 Sensor Data Quality for M152
EM2040 – Not used during this mission
CTD, DO – Data Ok
Seaking sonar – Data Ok
Magnetometer – Data Ok
ADCP – Data Ok
Side‐Scan Sonar (425kHz) – Not used
Side‐Scan Sonar (120kHz) – Not sued
Sub bottom profiler – Not Used
AESA Cameras – Not Used

Successful Dive. USBL died on the dive down. Acoustic failed at sea floor similar to M151.
Biocam worked. LED drivers were modified to run at higher voltage, creating a brighter flash.
Acoustic Modem (TrackLink) failed to communicate when circling at 150m altitude.
USBL stopped working 1 hours and 30 minutes into the mission. This was due to the battery failing tocharge. Issue with USBL not accepting charge. Seen this issue previously on DY94.
Mission plan overestimated the time need to complete the mission. Sub returned 2hrs and 30 minutes
earlier than expected.

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Fig. 13 3D Vehicle track for M152

Fig. 7.14 Mission Power Usage

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Fig. 7.15 Current Analysis

Fig. 7.16 Altitude tracking for M152

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7.1.7. Mission M153 Summary

Campaign: DY108

Mission No.

Operating Area

: Darwin Mounds: M153

Mission Objectives & Description
2nd BioCam survey at 6m of the eastern Darwin Mounds.
Mission Plan
‐ Deck Test for all suitable systems‐ Fast dive to 950m then more gentle until ADCP contact made with bottom‐ Circle and wait for position offset from the Acoustics or timeout‐ Start BioCam/EM2040/Edgetech then run survey.
‐ Return to surface potter until we arrive to pick it up.
Table 7.14 Vehicle Configuration and sensors used for M153
Sensors used
31) RDI workhorse ADCP 300kHz
downwards.
32) PHINS INS
33) Seabird 9+ CTD with dual CT sensors34) EM2040 multi‐beam35) EdgeTech 2200‐M 120‐425kHz sidescan and 2‐16kHz sub‐bottom
profiler (not used on this mission)36) 1 x colour downwards camera andflash (not used on this mission)37) 1 x colour forward camera and flash(not used on this mission)38) Tritech Seaking obstacle avoidancesonar39) Sonardyne G6 USBL Transponder

Table 7.15 Mission Conditions for M153
Start of Mission

Sub configuration

16) Rear winglets set at 6º pitched downwards.
17) Autosub 6k recovery line retention systemwith nylon springer lines18) 14.2kg positive buoyancy.
19) 6 x new battery packs.
20) New Autosub6000 launch and recovery
system (LARS)End of Mission

Time [logger]

18‐Sep‐2019 08:22:43

19‐Sep‐2019 09:18:00

Position [GPS]N59:51.327 W7:4.592

N59:51.283 W7:4.384

Sea state

1.5m

1.5m

Wind speed

15kn

Battery Voltage

49.95 [V]15 kn
44.21 [V](pack)

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Table 7.16 Mission Statistics for M153
Total Mission duration
24 hrs 55 mins
Avg. descent speed

Time on seabedsurveying
Avg. ascent speed

Mean ground speed atbottom1.01 [m/s]Distance travelled

90.2 [km]Mean motor power

323.1 [W]

Maximum Depth

1043.7 [m]Navigation Offset
AppliedMove 370m southand 120m west

Mission completed successfully: AUV successfully dived and was followed on the Ships USBL and the
LinkQuest Fish until the AUV moved into ‘WaitAtAlt’ mode where the LinkQuest communication
dropped out. Ship repositioned over vehicle and LinkQuest Fish was set to high power, this enabledintermittent comms with AUV meaning it was possible to send the required navigation offset. The AUVthen continued the mission and surfaced about 90 minutes later than expected, it is expected that thisis because of the currents, a number of lines can be seen to be timing out. The data also shows thatthe vehicle potentially hit the seabed although there is no visible damage to the AUV. The AUV wassuccessfully recovered.
Linkquest ‐ Same fault as previous missions, when AUV moves into ‘WaitAtAlt’ it is not possible tocommunicate with the AUV.
Tritech – From inspection of the Tritech node and data it appears that the Tritech head is not
functioning.
Depth – Inspection of the data shows that the vehicle depth sensor is reading less than that of the
CTD. The code on the lonworks node suggests that the latitude should be taken into consideration
when making the depth calculation, this had been updated earlier in the cruise but will update again
to see if this rectifies the issue.
Table 7.17 Sensor Data Quality for M153
EM2040 – N/ACTD, DO ‐ Ok
Seaking sonar – Data collected
Magnetometer – Ok
ADCP – Ok
Side‐Scan Sonar (425kHz) – N/A
Side‐Scan Sonar (120kHz) – N/A
Sub bottom profiler – N/A
AESA Cameras – N/A

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Fig. 7.17 3D Vehicle track for M153

Fig. 7.18 Battery voltage measured at the motor node for M153

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Fig. 7.19 Altitude tracking for M153

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7.1.8. Mission M154 Summary

Campaign: DY108

Mission No.

Operating Area

: Darwin Mounds: M154

Mission Objectives & Description
Run Edgetech survey of Eastern Darwin mounds followed by a short BioCam survey.
Table 7.18 Vehicle Configuration and sensors used for M154
Sensors used
Sub configuration40) RDI workhorse ADCP 300kHz
downwards.
41) PHINS INS
42) Seabird 9+ CTD with dual CT sensors43) EM2040 multi‐beam44) EdgeTech 2200‐M 120‐425kHz sidescan and 2‐16kHz sub‐bottom
profiler (not used on this mission)45) 1 x colour downwards camera andflash (not used on this mission)46) 1 x colour forward camera and flash(not used on this mission)47) Tritech Seaking obstacle avoidancesonar48) Sonardyne G6 USBL Transponder

Table 7.19 Mission Conditions for M154
Start of Mission21) Rear winglets set at 6º pitcheddownwards.
22) Autosub 6k recovery line retention
system with nylon springer lines23) 16.8kg positive buoyancy.
24) 6 x new battery packs.
25) New Autosub6000 launch andrecovery system (LARS)End of Mission

Time [logger]

20‐Sep‐2019 14:34:43

20‐Sep‐2019 17:10:53

Position [GPS]N59:51.411 W7:9.554

N59:51.246 W7:9.406

Sea state

1.5m

1.5m

Wind speed

12kn

12kn

Battery Voltage(pack)The vehicle was successfully launched but once in the water it was noticed that the heading from the
INS was not changing and the mission was abandoned.
-

The heading from the INS appeared to have frozen, it was possible this was occurring on deck
but was not noticed until the vehicle was in the water and had made a dramatic shift in its
orientation.

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7.1.9. Mission M155 Summary

Campaign: DY108/9

Mission No.

Operating Area

: Darwin Mounds (East): M155

Mission Objectives & Description
Perform a sidescan sonar survey over the east Darwin mounds area previously surveyed in 2011. The
purpose is to compare sidescan images from the two surveys to determine if the site has improved
since 2011. At the end of the survey complete a short Biocam survey.
Mission Plan
Edge Tech survey over the east Darwin mounds coral reef field. A repeat of the survey carried out in
2011, to determine the extent of recovery. After the edge tech survey a short Biocam mission with
Edge tech still operating at depths from 15m to 4m
Table 7.20 Vehicle Configuration and sensors used for M155
Sensors used
49) RDI workhorse ADCP 300kHz
downwards.
50) PHINS INS
51) Seabird 9+ CTD with dual CT sensors52) EM2040 multi‐beam (not used on
this mission)53) EdgeTech 2200‐M 120‐425kHz sidescan and 2‐16kHz sub‐bottom
profiler54) 1 x colour downwards camera andflash (not used on this mission)55) 1 x colour forward camera and flash(not used on this mission)56) Tritech Seaking obstacle avoidancesonar57) Sonardyne G6 USBL Transponder
58) Biocam, two flash panels and two
Class 4 lasers
Table 7.21 Mission Conditions for M155
Start of Mission

Sub configuration

26) Rear winglets set at 6º pitched downwards.
27) Autosub 6k recovery line retention systemwith nylon springer lines28) 16.9kg positive buoyancy.
29) 6 x new battery packs.
30) New Autosub6000 launch and recovery
system (LARS)End of Mission

Time [logger]

21‐Sep‐2019 14:39:20

22‐Sep‐2019 15:40:39

Position [GPS]N59:51.406 W7:9.501

N59:50.965 W7:8.309

Sea state

2

3Wind speed

12 knots

Battery Voltage

49.69 [V]20 knots
44.24 [V](pack)

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Table 7.22 Mission Statistics for M155
Total Mission duration
25 hrs 1 mins

Time on seabedsurveying

22 hrs 0mins

Avg. descent speed

0.34 m/s

Avg. ascent speed

0.39 m/s

Mean ground speed atbottom1.02 [m/s]Distance travelled

97 [km]Mean motor power

315.9 [W]

Maximum Depth

1063.3 [m]Approximate usefulvertical imagesn/aApproximate usefulforward images

n/aSuccessful Edge tech mission. However, just after the Biocam section of the dive started the Autosub
lost bottom lock and dived and hit the seabed. It aborted the mission and ascended to near the safe
depth of 160m (note a safe depth of 100m was programmed, unclear why the Autosub did not achieve
this depth). The mission was aborted via the Linquest system on the acoustic fish and the vehicle
surfaced 50m from the ship. Recovered on board safely. Later analysis showed the Autosub lost
bottom lock because the ADCP had failed. The Autosub then dived to try to reacquire the seabed,causing the collision with the seabed. Post mission the ADCP was removed and bench tested where it
was conformed both beams 2 & 4 were not longer working.
Successful EdgeTech mission, however loss of bottom lock just after the start of the Biocam section of
the mission resulted in the Autosub pitching downwards and colliding with the sea floor. The Autosub
then returned to close to the safe depth at which point the mission was aborted via the Linquest
acoustic system,‐ The Autosub did not return exactly to the safe depth. Aurtosub circled and pottered at 160m rather
than the configured 100m
‐ Bottom lock was lost due to an ADCP failure. Post mission analysis of the ADCP (removed from theNavigation tube) showed beam 2 and 4 were not working‐ We do not have a full understanding of what happened after the collision with the seabed. The
vehicle did return to somewhere near the safe depth, however post mission analysis showed all
mission script commands after the collision were actioned but then then skipped over rapidly (withina few minutes rather than the 2 to 3 hours programmed). We are unclear whether this is normal
behaviour.

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Table 7.23 Sensor Data Quality for M155
EM2040 – Not used during this mission
CTD, DO – Questionable data, depth data poor quality requires investigation.
Seaking sonar – Data Ok
Magnetometer – Data Ok
ADCP – Data Ok
Side‐Scan Sonar (425kHz) – Data OK
Side‐Scan Sonar (120kHz) – Not sued
Sub bottom profiler – Data Ok
AESA Cameras – Not Used

Fig. 7.20 3D Vehicle track for M155

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Voltage [V]Current [Amps]
Power [W]Fig. 7.21 Mission Power Usage for M155

Fig. 7.22 Current Analysis for M155

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Fig. 7.23 Altitude Tracking for M155

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7.1.10. Mission M156 Summary

Campaign: DY108/9

Mission No.

Operating Area

: Darwin Mounds (West): M156

Mission Objectives & Description
Test dive to check new ADCP followed by a Biocam dense grid survey of the Western Darwin mounds
coral reef site. This area was side scanned previously on this cruise and the dense grid hopes tohighlight key coral mounds within the area.
Mission Plan
Perform a test dive to check operation of the newly installed, and then carry out a dense grid Biocam
survey over the previously side scanned area to pick out key features.
Table 7.24 Vehicle Configuration and sensors used for M156
Sensors used
59) RDI workhorse ADCP 300kHz
downwards.
60) PHINS INS
61) Seabird 9+ CTD with dual CT sensors62) EM2040 multi‐beam (not used on
this mission)63) EdgeTech 2200‐M 120‐425kHz sidescan and 2‐16kHz sub‐bottom
profiler (not used on this mission)64) 1 x colour downwards camera andflash (not used on this mission)65) 1 x colour forward camera and flash(not used on this mission)66) Tritech Seaking obstacle avoidancesonar67) Sonardyne G6 USBL Transponder
68) Biocam, two flash panels and two
Class 4 lasers
Table 7.25 Mission Conditions for M156
Start of Mission

Sub configuration

31) Rear winglets set at 6º pitched downwards.
32) Autosub 6k recovery line retention systemwith nylon springer lines33) 16.9kg positive buoyancy.
34) 6 x new battery packs.
35) New Autosub6000 launch and recovery
system (LARS)End of Mission

Time [logger]

24‐Sep‐2019 13:01:37

25‐Sep‐2019 15:17:41

Position [GPS]N59:49.454 W7:21.677

N59:49.708 W7:22.520

Sea state

24Wind speed

20 knots

Battery Voltage

49.93 [V]30 knots
44.09 [V](pack)

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Table 7.26 Mission Statistics for M156
Total Mission duration
26 hrs 08 mins

Time on seabedsurveying

21 hrs 58 mins

Avg. descent speed

0.38 m/s

Avg. ascent speed

0.41 m/s

Mean ground speed atbottom1.07 [m/s]Distance travelled

92.9 [km]Maximum Depth

952.8 [m]Approximate usefulforward images

n/aMean motor power
Approximate usefulvertical images

n/a

The new ADCP was tested successfully by performing a dive to 900m to obtain DVL bottom lock andrun two test lines. The vehicle then ascended back to the surface again and paused where data was
offloaded to check ADCP performance. All appeared correct and so the vehicle was sent on theremaining Biocam mission. The vehicle performed correctly and we saw a better altitude tracking
performance than on earlier dives. The vehicle surfaced as expected and was recovered successfully
under demanding conditions.
The Biocam did not collect any data. Initial analysis suggests the cable between the Biocam and thelogger failing under pressure at 900m at the start of the Biocam mission. Then working again at 300m
on the ascent after the Biocam mission. Although power was still being supplied the Biocam did nor
receive any UDP messages from Autosub. Post mission analysis of the Logger tube data showed UDP
messages around the Autosub vehicle were working as normal. Therefore, the cable between the
Biocam and the logger is suspect.

Table 7.27 Sensor Data Quality for M156
EM2040 – Not used during this mission
CTD, DO – Data Ok, although a delay accrues during the mission so data does not align correctly atthe end of the mission
Seaking sonar – Data Ok
Magnetometer – Data Ok
ADCP – Data Ok
Side‐Scan Sonar (425kHz) – Not used
Side‐Scan Sonar (120kHz) – Not sued
Sub bottom profiler – Data Ok
AESA Cameras – Not Used
Biocam – No data due to Biocam cable failing under pressure

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Power [W]Current [Amps]

Voltage [V]Fig. 7.24 3D Vehicle track for M156

Fig. 7.25 Mission Power Usage for M156

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Fig. 7.26 Current Analysis for M156

Fig. 7.27 Altitude Tracking for M156

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Fig. 7.28 Improved Altitude tracking performance for M156

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7.2. HyBIS System Cruise Report
Operational Team: Dave Turner, Russell Locke & Emre Mutlu

Fig. 7.29 HyBIS on deck
7.2.1. Cruise Outline
HyBIS was used during DY108 for HD video and stills survey of the Darwin Mounds.
7.2.2. Stats
No. of dives DY108 (Dive nos. HY50 to HY62)
Water Depths
Total time at seabed or survey depth:
HyBIS total time in water:
Total Video (Apple ProRes 422)
Scorpio Images

13755m – 1072m
75:50 hrs
90:46 hrs
HD 4.17 TB
PAL 3.84 TB
26845 images – 102.2 GB

Master #1 Lacie Raid unit SER# NL4104NZ will be installed in the NOC media room for BODC to archiveand provide access for scientists post cruise.
Backup #1 Lacie Raid unit SER# NL41042D will be retained by the ROV team until BODC have archived
the Master unit.

7.2.3. Mobilisation
NOC Southampton:

2nd September to 5th September 2019

The mobilisation of Hybis in preparation for DY108 was conducted by the whole of the ROV team.
The HYBIS monitors and control rack were assembled in the first bay (furthest forward) of the mainlab, with the winch operator’s CLAM and CCTV monitors mounted at the end of the bench. The HYBIS
power supply unit was mounted on top of the portable table, inside of the High Voltage Cage. The
HYBIS team were given responsibility of the HV cage key and the Chief Engineer kept the key to the
key cabinet also kept inside the cage.
An Evergrip termination was still connected to the deep tow cable following the previous (trials) cruise.
After electrical testing, new fibre optic tails were spliced onto the cable. The results of the electricaland optical testing are shown below:

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Optical readings were taken from the Main Lab Junction box to the terminated end of the Deep Tow.
Red
Black
Grey

1310 nm‐11.15dB‐11.37dB‐11.12dB

1550 nm‐9.50dB‐10.82dB‐10.50dB

1310 nm9.91 km xxxdB Loss
9.91 km 6.7dB Loss
9.9 km 5.8dB loss

1550 nm9.91 km xxxdB Loss
9.91 km 5.6dB Loss
9.9 km xxxdB LossOTDR readings:
Red
Black
Grey

The termination was then connected to HYBIS with the red fibre used for telemetry and the black fibreused for the Scorpio camera. The vehicle was then tested using the 240V deck lead followed by the
HV supply and all functions worked correctly.

The electrical conductor readings were taken from the Deep Tow junction box in the winch room tothe terminated end of the Deep Tow.
Table 7.28 – RRS Discovery deep tow cable test results
Continuity of Conductors & Earth
L1 – L2
L1 – L3
L2 – L3
L1 – Earth
L2 – Earth
L3 – Earth
Insulation Resistance Test
L1 – L2
L1 – L3
L2 – L3
L1 – Earth
L2 – Earth
L3 – Earth

Test Results Ω
92.6
92.1
92.0
47.4
47.3
47.2
Test Results (GΩ)
3.27
4.46
3.47
2.59
3.00
2.53

7.2.4. De‐Mobilisation
The HyBIS system was prepared for demobilisation during the transit back to NOC Southampton. The
vehicle was stripped of lights and sensors and the cages were packed so that the HyBIS system wasready to be lifted off the ship.
During the de‐mobilisation another deep tow wire inspection was made and the fibre optic power
values were recorded on the IMS system. The Evergrip termination was cut off and returned to the
NOC ROV Hangar S1/55 for service and storage.
7.2.5. Deep Tow Cable
7.2.5.1. Umbilical Termination
During DY108, HyBis was the only piece of equipment attached to the deep tow cable underneath thehydraboom, so no wire swapping was required.

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There is now a working fusion splicing kit, OTDR, optical power meters and associated tools andconsumables on board the Discovery, located in aluminium boxes in the technician’s lab.
Suggestions/Recommendations
 Re‐test the umbilical cable during the de‐mob. Remove Evergrip termination from theumbilical and return to ROV hangar for refurbishment.
7.2.5.2. Active Heave Compensation
The Active Heave Compensation (AHC) of the deep tow cable was tested during the Discovery trials
cruise, which took place just before DY108. During testing, the main problem with the AHC was
identified and fixed.
The AHC was used on dive HY51 of DY108 during weather that would have normally produced poor
video footage, due to the large sea state. The water depth at the work site was 1046m and the AHC
was turned on at a depth of 900m. The AHC compensated well for the heave of the ship and HyBIS
maintained a constant altitude off the sea bed (± ~0.5m) providing stable video footage and reducing
the constant winch adjustments that are normally required. The data provided by the winch console
showed that the maximum heave compensation during the dive was 6.43m with the averagecompensation being 2.19m.
The AHC was subsequently used for every HyBIS dive and improved the image stability and video
quality substantially.

7.2.5.3. High Voltage Operations
As with previous cruises, the HV operations were discussed and agreed with the Chief Engineer andthe ETO prior to sailing. The key to the HV cage key remained in the possession of the HyBIS HV
appointed person for the duration of the trip. The HV was turned on at 110m depth, which allowed
just one stop during descent and was also the depth that the Active Heave Compensation (AHC) could
be turned on.
During recovery, the power to HyBIS was turned off at 100m depth and the bridge was notified when
this was done so that HyBIS could be recovered to deck.
A permit to work/Isolation certificate was filled out to show that the vehicle was isolated and HVprobes were used each time the HV JB was opened.
After the last HyBIS dive, the system was isolated and an isolation certificate was completed. The
system was then inspected by the Chief Engineer and ETO.
Suggestions/Recommendations
 The HV cage on the ship should be modified so that the front panel does not need to be
dismantled each time when the HV portable system and table is installed and removed.
 It would be highly recommended that the 230V supply in the HV cage be changed to aswitched socket for isolation and lockout/tag out purposes.

7.2.6. HyBIS System
During DY108 the HyBIS vehicle was stowed inside the hangar aft of the CTD slot. It was sat on a palletand moved out under the hydra‐boom prior to each launch. When deploying from this position andwhen the sampling module was attached (Dive HY50) it was found that the height between theEvergrip and the first set of rollers was not sufficient to allow any floats to be attached to the wire,

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without first opening the bulwark doors. During dive HY50 it was decided to put all five floats onto thewire when HyBIS was approximately 12m under the surface.
The associated HyBIS spares boxes and consumables were stowed in cages in the main hangar. Decktesting was achieved using the 240V AC deck lead plugged into a socket in the hanger. The deep tow
cable was not removed from the vehicle during DY108 so during deck testing, communications weredone using the deep tow fibres.

7.2.6.1. Vehicle
7.2.6.1.1 Hydraulic System
The only hydraulic function used on DY108 was the camera tilt.
Suggestions/Recommendations
 Flush and replace hydraulic oil before next HyBIS cruise.
7.2.6.1.2 Thrusters
The thrusters were used significantly during DY108 and worked well. Small oil leak on starboard
thruster.
Suggestions/Recommendations
 Drain all thrusters. Strip and check for signs of wear.
 Fix oil leak on starboard thruster
7.2.6.1.3 Modules
7.2.6.1.3.1 Sampling
The sampling module was mobilised for DY108 and attached to Hybis for the first dive (HY50), which
was to be a reconnaissance and possible recovery of a lander. Unfortunately, due to the cable failure
described, the dive was aborted and the sampling module was not used again during the cruise.
7.2.6.1.3.2 Downward video
The downward video frame was used for all but one of the dives during DY108. It was modified toaccommodate an extension pole, grapple hook and lifting strop for the recovery of the marker buoys(HY52 & HY53).
7.2.6.1.3.3 Grab module
Not mobilised for this cruise.
7.2.6.1.4 Cameras
Two Super Scorpio HD cameras were made available for DY108 from the Isis ROV equipment. Unit
Serial# SSC102 was mounted onto HyBIS for the duration of the trip.
During dive HY54‐power‐up and after two days of HyBIS not being used, the Super Scorpio camera
would not come to life. The power was cycled several times and it could be seen from the fibre optic
rattler that the camera was sending a signal to topside. After approximately five minutes, and a final
power cycle, the camera came to life but had lost all of its internal set‐up parameters. Unit SSC102
was the camera that had just been returned from having its internal battery replaced, but it appears
that the repair was unsuccessful.
It was noticed during dives HY54 and HY55 that the Delrin shroud of the Super Scorpio camera could
be seen at the corners of the image. The shroud was adjusted during HY56 pre‐dive by rotating until
it disappeared from the field of view.
During DY108 white balancing was not required as this was done by post processing of the video andimages.

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The download of images was done with a laptop and a power supply in the hanger.
Two Bowtech PAL cameras were available as part of the HyBIS equipment. During the first pre‐dive ofthe trip it was noticed that the upward looking camera image was distorted and the display was cutting
in and out. To test the cables the cameras were swapped over but the problem remained with thesame camera unit ruling out a problem with the camera leads. The faulty camera was dismantled andit was suspected that the internal wiring might be suffering from dry joints. The internal wiring was
replaced and the camera reassembled but the same display problem was seen. The problem may lie
in the actual camera unit. For the rest of DY108 HyBIS was operated with one PAL camera and nospare.
Suggestions/Recommendations
 Look into purchasing replacement HyBIS Bowtech PAL camera Contact Insite Pacific and seek advice concerning failure of Super Scorpio internal
battery
7.2.6.1.4.1 Super Scorpio Specs:
HD: 1920 x 1080 / (50P), 50i, 25p
12.3 MEGA‐PIXEL quality for Ultra‐High Definition (4672 x 2628‐pixel) Still Images
Sensor: Exmor Back‐illuminated CMOS 1/2.88” (6.2mm)
10X Optical Zoom Lens (26.3mm ‐ 263mm in 35mm format)
Focal Distance= f= 3.8mm – 38mm
Aperture: F1.8 ‐ F9.6
64GB Internal Flash Memory
On recovery deck download of images (Ethernet deck cable)

7.2.6.1.5 Lights
During video transect dives, three Cathx Aphos lights were pointed downwards to illuminate the
Scorpio camera and two DSPL Lumos LED lights faced forwards for the PAL tooling camera.
Suggestions/Recommendations
 Return Cathyx lights to ISIS spares container and DSPL Lumos LED lights to MPUS spares.
7.2.6.1.6 Scaling Lasers
Two NOC lasers were used for DY108 with two spares. The lasers worked well for the duration of thecruise.
Suggestions/Recommendations
 Check lasers for damage and replace seals as part of their routine maintenance.
7.2.6.1.7 Valeport VA500 Pressure / Altimeter transducer
The pressure/altimeter transducer worked well for most of DY108 and proved very useful to the winch
driver during bottom operations.
During dive HY57 the altimeter did not return a signal to the GUI PC for a short period of time. The
signal then re‐appeared of its own accord.
During dive HY58, altimeter cut out again for 5 minutes, then came back to life of its own accord.
During the last four HyBIS dives, no further problems with the altimeter were observed.

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7.2.6.1.8 Tritech Sonar
The HyBIS 4000m Tritech sonar was used throughout DY108 and worked successfully for the durationof the cruise. It proved to be very useful during the location of the marker buoys and lander. It also
imaged the mounds and the bedforms (sandwaves, ripples) very well
Suggestions/Recommendations
 Develop a method to record the forward sonar data for later re‐play/analysis
7.2.6.1.9 Compass
The Xsense MTi‐30 AHRS compass worked well during DY108. The compass offset was set to zero as
per previous cruise (DY103) and this seemed to correctly reflect the vehicles movements during video
transects.
Suggestions/Recommendations
 Remove the ‐25 degree offset built into the GUI software.
7.2.6.1.10 Vehicle cabling
During the first HyBIS dive (HY50) the vehicle powered up and worked correctly to a depth ofapproximately 250m at which point the power to the vehicle was lost and HyBIS was recovered.
At first, it was thought that the umbilical had failed as the vehicle still powered up using the deck lead.
Continuity and insulation Resistance checks were made on the cable but the test results looked okay
and were similar to the values obtained during the mobilisation.
The fault was eventually traced to the 240V power lead from the transformer to the high power tube.
On visual inspection the cable had a tight 90° bend and when tested it was found to be faulty.
The cable was replaced and when the transformer overload was re‐set, the vehicle powered up
successfully again.

7.2.6.2. Lab Setup and Rack Mount Case
The rack unit and lab set‐up was identical to that of HyBIS cruise DY094 & DY103.
7.2.6.2.1 Mini HP GUI Machine
The GUI PC was used to run the Labview status displays for HyBIS.
7.2.6.2.2 Mini HP OFOP Machine
The OFOP PC and monitor were used to run the OFOP software. A second monitor was provided forscience logging of ocean floor observations.
7.2.6.2.3 AJA KiPro video recorders
Two AJA Rackmounted KiPro units were used to record video. The Top unit was assigned to the Scorpio
HD camera. The lower unit was connected to the 720P50 quad which was connected to the PAL
tooling camera. The copying of the KiPro disks to the Lacie units was done by the HyBIS team.
During dive HY56 the PAL KiPro Unit Stopped recording of own accord. The unit then locked up andwould not mount formatted solid state drive unit. When viewed on the Mac‐Mini, the .mov file onthat particular 250Gb drive unit was corrupt and could not be viewed. Afterwards it was noticed thatthat particular drive unit would not click/lock into the KiPro deck and could be removed without using
the release button. It was believed that the unit might have not been fully engaged and somehow
created a corrupt file. A spare 250Gb drive unit was installed and the old drive unit was labelled faulty.
No further KiPro issues occurred.

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7.2.6.2.4 HD Video Overlay
The new modified HYBIS video overlay worked well during DY108 with no freezing or crashes.
7.2.6.3. Football Floats
The football floats were not required for the majority of the cruise and were only used when thesampling module was attached to HyBIS during dive HY50.
It should be noted that when deploying HyBIS using the hydra‐boom, there is not sufficient height
above the Evergrip termination to attach floats prior to deployment.
Suggestions/Recommendations
 Modify HyBIS deployment procedure to describe the number of floats and their positions
when deploying HyBIS with the Hydra‐boom on the RRS Discovery.
7.2.6.4. Sonardyne Beacon
One of the ROV Sonardyne WMT beacons (2709) was used for each HyBIS deployment on DY108.
Generally, the beacon tracked well apart from just one dive (HY54) where connection was intermittent
and there was larger than normal error in the vehicle position. It was noted that the ship was also
struggling to hold position due to the weather during the dive, so the problems with tracking were put
down to the environmental conditions at that time.
The beacon was removed from the vehicle after each dive and connected to the charger and HyBIS
laptop in preparation for the next dive.

7.2.7. HyBIS specific operations
7.2.7.1. Marker Buoy Recoveries ‐ Dives HY52 & HY53
Several marker buoys were placed on the seabed during a previous visit to the Darwin Mounds. It was
believed that two of the markers might interfere with the operation of the AUV during DY108 andafter a visual inspection of one of the markers during HyBIS dive HY51 it was decided to try and recoverthem.
HyBIS was rigged for the recovery by attaching a strop to the central aluminium channel of the video
module. An aluminium pole was also attached to the channel, which protruded approximately 1.5m
out the front of the vehicle. A master link and snap hook were attached to the end of the strop which
was then run along the length of the pole and secured in place with cable‐ties (See Fig. 7.30).
During both dives, the position of the markers was located with the Tritech Super Sea‐King scanningsonar, and the ship was manoeuvred towards that position. The Active Heave Compensation (AHC)
was turned on during the HyBIS descent and this helped enormously with the stability of the vehicle
during the marker buoy recoveries. When visual contact was made with the markers, HyBIS was
manoeuvred so that the snap hook caught around the rope, just below the marker buoy. The winch
driver then hauled on the deep tow, to take the weight of the buoy on the hook so that it detacheditself from the aluminium pole and swung underneath the HyBIS vehicle.
As HyBIS was recovered to deck, the weight of the marker buoy was taken by the rex‐roth winch, sothat HyBIS could be detached from the package and landed on deck. The marker buoy was then also
recovered to deck.

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Fig. 7.30 ‐ Photo showing marker buoy and snap hook arrangement.

Fig. 7.31 ‐ Photo showing ecology attached to glass sphere.

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7.2.7.2. Lander Inspection ‐ Dive HY62
Dive HY62 was the last HyBIS dive of DY108 and was the video inspection of a lander that had beenreleased and could still be ranged, but had not come to the surface.
The ship was positioned close to the estimated position of the lander and HyBIS was lowered to theseabed. A target was observed straight away using the Tritech forward scanning sonar and was withina range of 50m. The ship was then manoeuvred towards the target until it came into view on the video
display.
The lander appeared to be covered with silt and the ADCP had been ripped off and lay close by, still
attached to the power cable (Figs. 7.32 & 7.33).

Fig. 7.32 ‐ Photo showing silt covered lander with detached ADCP.

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Fig. 7.33 ‐ Photo showing close up of detached ADCP.

It was not possible to make a recovery attempt with the video inspection set‐up of HyBIS and it was
discussed whether HyBIS should be recovered and re‐deployed with the sample module andmanipulator arm, but there was not enough time left in the schedule to attempt it. The video did
however provide good information on the state of the lander and the fact that it was probably
damaged by a passing trawl.

7.2.7.3. HyBIS Dive Hr Summary
Dive 1 09/09/2019
Station 02
HY50 GMT
Difference between times
In Water
13:30:00
Hr
Seabed
13:58:00
Hr
00:28:00
In Water Time
Off Seabed
13:59:00
Hr
00:01:00
On Bottom TimeOn Surface
14:22:00
Hr
00:23:00
Dive aborted at 350m due to power fault
Dive 2 11/09/2019
Station 10
HY51
In WaterSeabedOff Seabed
On Surface

Cruise report No. 66

GMT
19:10:00
19:59:00
02:07:00
02:50:00

Difference between times
Hr
Hr
00:49:00
In Water TimeHr
06:08:00
On Bottom TimeHr
00:43:00

00:52:00
00:01:00

07:40:00
06:08:00

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Dive 3 12/09/2019
Station 15
HY52
In WaterSeabedOff Seabed
On Surface

GMT
17:32:00
18:01:00
18:40:00
19:27:00

Difference between times
Hr
Hr
00:29:00
In Water TimeHr
00:39:00
On Bottom TimeHr
00:47:00

Dive 4 12/09/2019
Station 16
HY53
In WaterSeabedOff Seabed
On Surface

GMT
21:22:00
21:58:00
22:38:00
23:26:00

Difference between times
Hr
Hr
00:36:00
In Water TimeHr
00:40:00
On Bottom TimeHr
00:48:00

Dive 5 16/09/2019
Station 22
HY54
In WaterSeabedOff Seabed
On Surface

GMT
16:50:00
17:49:00
02:20:00
02:54:00

Difference between times
Hr
Hr
00:59:00
In Water TimeHr
08:31:00
On Bottom TimeHr
00:34:00

Dive 6 17/09/2019
Station 27
HY55
In WaterSeabedOff Seabed
On Surface

GMT
16:28:00
17:06:00
02:34:00
03:03:00

Difference between times
Hr
Hr
00:38:00
In Water TimeHr
09:28:00
On Bottom TimeHr
00:29:00

Dive 7 18/09/2019
Station 33
HY56
In WaterSeabedOff Seabed
On Surface

GMT
16:18:00
16:53:00
02:32:00
03:04:00

Difference between times
Hr
Hr
00:35:00
In Water TimeHr
09:39:00
On Bottom TimeHr
00:32:00

Dive 8 19/09/2019
Station 37
HY57
In WaterSeabedOff Seabed
On Surface

GMT
16:25:00
16:56:00
02:19:00
02:47:00

Difference between times
Hr
Hr
00:31:00
In Water TimeHr
09:23:00
On Bottom TimeHr
00:28:00

Cruise report No. 66

01:55:00
00:39:00

02:04:00
00:40:00

10:04:00
08:31:00

10:35:00
09:28:00

10:46:00
09:39:00

10:22:00
09:23:00

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Dive 9 20/09/2019
Station 43
HY58
In WaterSeabedOff Seabed
On Surface

GMT
17:58:00
18:32:00
02:23:00
02:50:00

Difference between times
Hr
Hr
00:34:00
In Water TimeHr
07:51:00
On Bottom Time
Hr
00:27:00

Dive 10 22/09/2019
Station 46
HY59
In WaterSeabedOff Seabed
On Surface

GMT
16:58:00
17:31:00
01:48:00
02:18:00

Difference between times
Hr
Hr
00:33:00
In Water TimeHr
08:17:00
On Bottom Time
Hr
00:30:00

Dive 11 23/09/2019
Station 52
HY60
In WaterSeabedOff Seabed
On Surface

GMT
17:16:00
17:49:00
02:06:00
02:36:00

Difference between times
Hr
Hr
00:33:00
In Water TimeHr
08:17:00
On Bottom Time
Hr
00:30:00

Dive 12 24/09/2019
Station 55
HY61
In WaterSeabedOff Seabed
On Surface

GMT
19:32:00
20:06:00
02:15:00
02:40:00

Difference between times
Hr
Hr
00:34:00
In Water TimeHr
06:09:00
On Bottom Time
Hr
00:25:00

Dive 13 24/09/2019
Station 57
HY62
In WaterSeabedOff Seabed
On Surface

GMT
13:56:00
14:28:00
15:15:00
15:44:00

Difference between times
Hr
Hr
00:32:00
In Water TimeHr
00:47:00
On Bottom TimeHr
00:29:00

Cruise report No. 66

08:52:00
07:51:00

09:20:00
08:17:00

09:20:00
08:17:00

07:08:00
06:09:00

01:48:00
00:47:00

Total Water Time (Days}
Total Bottom Time (Days)

3.781944444
3.159722222

Total Water Time (Hrs)
Total Bottom Time (Hrs)

90:46:00
75:50:00

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7.2.8. HyBIS Media Data
Scorpio Video

Pal Video

HY50
HY51
HY52
HY53
HY54
HY55
HY56
HY57
HY58
HY59
HY60
HY61
HY62

0.0
387.0
77.2
90.7
462.0
527.7
441.5
517.3
438.1
460.5
457.1
348.1
66.3
4273.5
4.17

GB
TB

Files

Data

0.0
365.2
72.9
85.1
437.0
495.7
366.6
483.4
398.2
422.2
422.3
319.8
61.4

0
2156
237
258
2980
3382
3445
3352
2805
2967
2783
2200
280

0.0
8.4
0.8
0.8
10.7
13.0
13.7
12.1
12.5
10.9
10.7
7.7
0.9

3929.83.8426845 102.2
0.10

Total storage used (GB)Total storage used (TB)

Cruise report No. 66

Stills:8305.480
8.111

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7.3. Coring
Operational Team: Richard Phipps, with help from Brian Bett7.3.1. Boxcorer
The corer used (Fig. 7.34) was a NOC NMF supplied stainless steel United States Naval Electronics
Laboratory (USNEL) Mk 2‐type spade box corer, having a nominal 50 × 50 cm (0.25 m2) seabedsampling aperture (see e.g. Gage & Bett, 2005; Narayanaswamy et al., 2016). The corer was rigged
and operated in conventional fashion, with the penetration limiting stops having been removed prior
to the first deployment. Note that to maximise sampling performance, the core box was specificallyground to a fine profile match with the spade sealing surface, and the supernatant draining
mechanism and opening side of the box were sealed closed during pre‐cruise preparation. The corer
was operated in conjunction with a Sonardyne Wideband Sub‐Mini 6 Plus USBL transponder that was
clamped to the coring warp 50 m above the corer. Typically, the corer was lowered to c. 50 m above
the seabed at a maximum of 0.8 ms‐1, if required the ship was then repositioned in an attempt to movethe corer closer to the intended seafloor target point, the final pay out speed was 0.5 ms‐1, with a c. 5
m wire over‐run on bottom contact, and immediate hauling at 0.3 ms‐1, and subsequent recovery at
maximum 0.8 ms‐1. Pull‐out tension typically reflected seabed habitat type: mounds averaged 1.5 T(1.4‐1.9 T), tails averaged 2.9 T (1.6‐4.5 T). See separate account of samples retained.

Fig. 7.34 Boxcorer on deck

7.3.2. Megacorer
The corer used (Fig. 7.35) was a NOC NMF supplied Bowers & Connelly Megacorer (see e.g. Gage &Bett, 2005) with extended protective frame and three additional layers of ballast lead sheet. In allcases during the present cruise the corer was rigged in MgC02+2 format (2 × 10 cm ID coring units,
and 2 × 59 mm ID coring units) and deployed in conventional fashion. The corer was operated inconjunction with a Sonardyne Wideband Sub‐Mini 6 Plus USBL transponder that was clamped to thecoring warp 50 m above the corer. Typically, the corer was lower to c. 50 m above the seabed at a

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maximum of 0.8 ms‐1, if required the ship was then repositioned in an attempt to move the corer
closer to the intended seafloor target point, the final pay out speed was 0.4 ms‐1, with a c. 5 m wire
over‐run on bottom contact, a 1‐minute wait period, then hauling at 0.3 ms‐1, and subsequent
recovery at maximum 0.8 ms‐1. The corer was deployed on five occasions, each on a mound target. No
sediment samples were recovered. Coral fragments were retained dry from deployment DY108‐040;
coral fragments were retained dry from deployments DY108‐050 & 051 from the same mound target;
and a polychaete and an amphipod were also retained from deployment DY108‐051, and preservedin ethanol.

Fig. 7.35 Megacorer on deck

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7.4. CTD
Operational Team: Jeff Benson, Billy Platt
7.4.1. CTD system configurations
1) One CTD system was prepared. The water sampling arrangement was a 24‐way stainlesssteel frame system (s/n SBE CTD6), and the initial sensor configuration was as follows:
Sea‐Bird 9plus underwater unit, s/n 09P‐77801‐1182
Sea‐Bird 3P temperature sensor, s/n 03P‐4814, Frequency 1 (primary)
Sea‐Bird 4C conductivity sensor, s/n 04C‐2165, Frequency 2 (primary)
Digiquartz temperature compensated pressure sensor, s/n 129735 Frequency 3
Sea‐Bird 3P temperature sensor, s/n 03P‐4816, Frequency 4 (secondary)
Sea‐Bird 4C conductivity sensor, s/n 04C‐3258, Frequency 5 (secondary)
Sea‐Bird 5T submersible pump, s/n 05T‐3086, (primary)
Sea‐Bird 5T submersible pump, s/n 05T‐3090, (secondary)
Sea‐Bird 32 Carousel 24 position pylon, s/n 32‐60380‐0805
Sea‐Bird 11plus deck unit, s/n 11P‐24680‐0589 (main)
Sea‐Bird 11plus deck unit, s/n 11P‐34173‐0676 (back‐up logging)2) The auxiliary input initial sensor configuration was as follows:
Sea‐Bird 43 dissolved oxygen sensor, s/n 43‐1882 (V0) (primary)
Sea‐Bird 43 dissolved oxygen sensor, s/n 43‐2818 (V1) (secondary)Chelsea Aquatracka MKIII fluorometer, s/n 88‐2615‐126 (V2)Benthos PSA‐916T altimeter, s/n 62679 (V3)
Biospherical QCP‐2350‐HP DWIRR PAR sensor, s/n 70510 (V4)
Biospherical QCP‐2350‐HP UWIRR PAR sensor, s/n 70520 (V5)WETLabs BBRTD light scattering sensor, s/n BBRTD‐5466 (V6)WETLabs C‐Star 25cm path transmissometer, s/n CST‐1654DR (V7)3) Other sensors & instruments:
TRDI Workhorse Monitor 300kHz Downward‐looking LADCP, s/n 1855
TRDI Workhorse Monitor 300kHz Downward‐looking LADCP, s/n 4275
NOCS Workhorse LADCP battery pack pressure case, s/n WH007
OTE 10L water samplers, s/n’s 1B through 24B
MDS titanium CTD swivel, s/n 1246‐1
4) Sea‐Bird 9plus configuration file DY108_1182_SS.xmlcon was used for the stainless steel
frame CTD casts 001 – 003. Sea‐Bird 9plus configuration file DY108_1182_1940_SS.xmlcon
was used for the stainless steel frame CTD casts 004 – 048.
5) The spare water sampling arrangement was a 24‐way stainless steel frame system (s/n SBE
CTD1). The spare sensors were as follows:
Sea‐Bird 9plus underwater unit, s/n 09P‐54047‐0943
Sea‐Bird 3P temperature sensor, s/n 03P‐4381, 03P‐4383 and 03P‐4593
Sea‐Bird 4C conductivity sensor, s/n 04C‐2450, 04C‐2571 and 04C‐2580
Digiquartz temperature compensated pressure sensor, s/n 110557

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Sea‐Bird 5T submersible pump, s/n 05T‐6320, 05T‐6916 and 05T‐7515
Sea‐Bird 32 Carousel 24 position pylon, s/n 32‐34173‐0493
6) The spare auxiliary input initial sensor configuration was as follows:
Sea‐Bird 43 dissolved oxygen sensor, s/n 43‐1940
Chelsea Aquatracka MKIII fluorometer, s/n 88‐2050‐095 and 88‐2960‐163
Benthos PSA‐916T altimeter, s/n 59494
WETLabs BBRTD light scattering sensor, s/n BBRTD‐759R and BBRTD‐1055
WETLabs C‐Star 25cm path transmissometer, s/n CST‐1718TR and CST‐1837TR
7) Spare sensors & instruments:
TRDI Workhorse Monitor 300kHz LADCP, s/n 12369, 13329, 15288 and 23444
NOCS Workhorse LADCP battery pack pressure case, s/n WH006T and WH008T
OTE 10L water samplers, s/n’s 1A through 24A
MDS titanium CTD swivel, s/n 1253‐2
Changes to instrument suite: 43‐1940 replaced 43‐1882 for casts 004‐048. PAR sensor s/n 70520
removed from frame for casts 005‐006 to test BioCam USBL modem. LADCP battery pack s/n WH006T
replaced s/n WH007 for the second series of 24 hour CTD yo‐yo’s, as the original battery pack required
more than 3 hours of re‐charging.
Total number of casts ‐ 48
Casts deeper than 2000m ‐ 0
Deepest cast ‐ 1785m
7.4.2. Technical detail report
7.4.2.1. S/S CTD on CTD1 with titanium CTD swivel
CTD wire 1 was inspected before the start of DY107 and re‐terminated at the sea cable end. The sea
cable end was terminated with the normal S&M CTD termination; it was load tested by following thestandard procedure of being pulled at 0.5T, 1.0T, 1.5T and 2.0T. The termination assembly was held
for 5 minutes at each and re‐torqued between each. It had a ‘megger’ value of >1000 MOhms andinternal resistance of 70.1 Ohms post‐cruise. The termination was tested at the start of DY108 and it
had a ‘megger’ value of >1000 MOhms and internal resistance of 69.7 Ohms. This remained for theduration of the cruise.
Casts 001 was a cast to 1600m to check termination electrical integrity, test other instruments(acoustic releases and USBL beacons), to obtain water for the sediment trap mooring, and to checksensor performance. At the beginning of the down cast the primary oxygen sensor exhibited noise anddrift, along with erratic readings, compared to the secondary oxygen, and was subsequently checkedon deck post‐deployment and flushing. The readings were not similar enough to confirm the sensor
was functioning properly. The primary oxygen sensor was left in place for casts 002 & 003 (mini‐yoyo),and exhibited identical problems. Prior to cast 004 the cable was replaced for deck tests, and nochange was observed. Thus s/n 43‐1882 was then replaced with s/n 43‐1940.

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Deployments 005 to 006 did not have the Biospherical UWIRR sensor, as it was removed to test the
BioCam USBL modem. (The power supply provided for the USBL was not sufficiently depth rated totest the modem to greater than 1000m.) The Sea‐Bird 9P underwater unit was used to supply +9 to+28V required for the modem.
During cast 020 the altimeter began to display signs of intermittent cable failure, as the height offbottom was fixed at approximately 9m on the downcast, until a range of 7 to 8m was actually reached.
As this was during the first 24 hour BLT CTD yo‐yo series, the bottom was well known from previous
deployments, and reaching the target range of less than 10m off the bottom was attainable. The
altimeter cable was replaced at the end of the first series of yo‐yo deployments, cast 026, and began
to read correctly until cast 032, when the same symptoms reappeared.
The secondary conductivity sensor started to give “noisy” readings at 1350m depth during thedowncast on 027, and continued through cast 034. As the measurements were consistent with theoverall trend of the primary sensor, the cause of the “noise” was suspected to be biofouling.
During deployment 034 the CTD frame made contact with the bottom. (A separate report provides
these details.) After recovery to deck, prior to cast 035, the altimeter cable was replaced, and thesecondary conductivity sensor cleaned and flushed. These remedies worked until cast 041, when thesecondary conductivity again became “noisy”. The altimeter also resumed not working correctly at a
range of 10m from the bottom. The BBRTD showed “spikes” from 300m through the thermocline,
during upcasts, from deployment 042.
Only one titanium CTD swivel was used with the CTD frame, and it was refurbished MDS titanium CTD
swivel s/n 1246‐1; no problems or oil leaks observed.

7.4.2.2. LADCP
Two different pairs of command files were used during the cruise; one provided by RSMAS for the
single deployments, and the other provided by BAS for the 24 hour yo‐yo deployments. An explanationof the BAS command file set is attached in Appendix B.
Deployment of the Slave instrument on DY108_006s resulted in 4 separate files. The first file,
DY108_006s, stopped recording approximately 20 minutes before the Master file of DY108_006m.
The next three Slave files all stopped and started sequentially, and were named DY108_006a_s,
DY108_006b_s and DY108_006c_s. None of these three files appear to have any meaningful data.
At the finish of the first 24 hour CTD yo‐yo series, the Slave LADCP recorded for only a few minutes.
The command files were checked again for any errors or missing characters prior to re‐deployment
for the second 24 hour yo‐yo. Both instruments worked correctly for the entire second series, whichindicates a possible intermittent connection within the LADCP Star cable on the CTD frame as thecause of the non‐recording of data to the Slave instrument.

7.4.2.3. AUTOSAL
A Guildline 8400B, s/n 65764, was installed in the Salinometer Room as the main instrument forsalinity analysis. The Autosal set point was 21C, and samples were processed according to WOCE cruise
guidelines: The salinometer was standardized at the beginning of the first set of samples, and checked

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with an additional standard analysed prior to setting the RS. Once standardized the Autosal was not
adjusted for the duration of sampling.
A standard was analysed after each crate of samples to monitor & record drift (second standard
analysed after sample 24, third standard analysed after sample 48, etc).
Standards were labeled sequentially and increasing, beginning with number 9000. Standard deviation
set to 0.00002. 2.5 crates of salinity samples were analysed, with 7 bottles of standard used to monitor
the instrument drift. The electronic standby value after the standardisation was stable at 6132 to 6136
for the duration of the cruise.The spare salinometer, s/n 68426, was not used.

7.4.3. Configuration files
Stainless CTD frame:Casts 001 – 003
Date: 09/06/2019
Instrument configuration file: C:\Users\sandm\Documents\Cruises\DY108_109\Seasave Setup
Files\DY108_1182_SS.xmlcon
Configuration report for SBE 911plus/917plus CTD‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐
Frequency channels suppressed : 0
Voltage words suppressed : 0
Computer interface: RS‐232C
Deck unit: SBE11plus Firmware Version < 5.0
Scans to average:1
NMEA position data added : Yes
NMEA depth data added: No
NMEA time added: No
NMEA device connected to : PC
Surface PAR voltage added : No
Scan time added: Yes
1) Frequency 0, Temperature
Serial number : 03P‐4814
Calibrated on : 14 June 2018
G
: 4.30111327e‐003
H: 6.24737110e‐004
I: 1.86297758e‐005
J: 1.29851757e‐006
F0: 1000.000
Slope: 1.00000000
Offset: 0.0000
2) Frequency 1, Conductivity
Serial number : 04C‐2165
Calibrated on : 23 August 2017G
: ‐9.76338109e+000
H: 1.34212964e+000
I: ‐2.03325982e‐003
J: 2.01310127e‐004
CTcor: 3.2500e‐006
CPcor: ‐9.57000000e‐008
Slope: 1.00000000
Offset: 0.00000

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3) Frequency 2, Pressure, Digiquartz with TC
Serial number : 129735
Calibrated on : 3 November 2017
C1
: ‐6.064446e+004
C2: 6.966022e‐002
C3: 1.971200e‐002
D1: 2.882500e‐002
D2: 0.000000e+000
T1: 3.029594e+001
T2: ‐6.713680e‐005
T3: 4.165390e‐006
T4: 0.000000e+000
T5: 0.000000e+000
Slope: 0.99982000
Offset: ‐1.48930
AD590M: 1.279180e‐002
AD590B: ‐8.821250e+000
4) Frequency 3, Temperature, 2Serial number : 03P‐4816
Calibrated on : 23 August 2017G
: 4.30497192e‐003
H: 6.34223731e‐004
I: 2.17264599e‐005
J: 2.02839765e‐006
F0: 1000.000
Slope: 1.00000000
Offset: 0.0000
5) Frequency 4, Conductivity, 2
Serial number : 04C‐3258
Calibrated on : 25 August 2017G
: ‐1.06581670e+001
H: 1.36071859e+000
I: 1.30128231e‐004
J: 6.09502147e‐005
CTcor: 3.2500e‐006
CPcor: ‐9.57000000e‐008
Slope: 1.00000000
Offset: 0.00000
6) A/D voltage 0, Oxygen, SBE 43
Serial number : 43‐1882
Calibrated on : 21 July 2018
Equation : Sea‐Bird
Soc: 4.84100e‐001
Offset: ‐4.91000e‐001
A: ‐4.34740e‐003
B: 2.09570e‐004
C: ‐3.16150e‐060
E: 3.60000e‐002
Tau20: 1.23000e+000
D1: 1.92634e‐004
D2: ‐4.64803e‐002
H1: ‐3.30000e‐002
H2: 5.00000e+003
H3: 1.45000e+003

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7) A/D voltage 1, Oxygen, SBE 43, 2
Serial number : 43‐2818
Calibrated on : 24 August 2017
Equation : Sea‐Bird
Soc: 4.65400e‐001
Offset: ‐4.98300e‐001
A: ‐4.41050e‐003
B: 2.34710e‐004
C: ‐3.56300e‐006
E: 3.60000e‐002
Tau20: 1.38000e+000
D1: 1.92634e‐004
D2: ‐4.64803e‐002
H1: ‐3.30000e‐002
H2: 5.00000e+003
H3: 1.45000e+003
8) A/D voltage 2, Fluorometer, Chelsea Aqua 3
Serial number : 88‐2615‐126
Calibrated on : 16 August 2018
VB
: 0.593340
V1: 2.105980
Vacetone : 0.756140
Scale factor : 1.000000
Slope: 1.000000
Offset: 0.000000
9) A/D voltage 3, Altimeter
Serial number : 62679
Calibrated on : 14 Janusry 2014
Scale factor : 15.000
Offset: 0.000
10) A/D voltage 4, PAR/Irradiance, Biospherical/Licor
Serial number: 70510
Calibrated on: 27 June 2019M
: 1.00000000
B: 0.00000000
Calibration constant : 20300000000.00000000
Multiplier: 1.00000000
Offset: ‐0.05009162
11) A/D voltage 5, PAR/Irradiance, Biospherical/Licor, 2Serial number: 70520
Calibrated on: 27 June 2019M
: 1.00000000
B: 0.00000000
Calibration constant : 19900000000.00000000
Multiplier: 1.00000000
Offset: ‐0.05148773
12) A/D voltage 6, Transmissometer, WET Labs C‐Star
Serial number : CST‐1654DR
Calibrated on : 7 April 2017M
: 21.1627
B: ‐0.1550

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Path length : 0.250
13) A/D voltage 7, OBS, WET Labs, ECO‐BB
Serial number : BBRTD‐5466
Calibrated on : 4 February 2019
ScaleFactor : 0.003307
Dark output : 0.051000
Scan length: 41Casts 004 – 048
Date: 09/10/2019
Instrument configuration file: C:\Users\sandm\Documents\Cruises\DY108_109\Seasave Setup
Files\DY108_1182_1940.xmlcon
Configuration report for SBE 911plus/917plus CTD‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐
Frequency channels suppressed : 0
Voltage words suppressed : 0
Computer interface: RS‐232C
Deck unit: SBE11plus Firmware Version < 5.0
Scans to average:1
NMEA position data added : Yes
NMEA depth data added: No
NMEA time added: No
NMEA device connected to : PC
Surface PAR voltage added : No
Scan time added: Yes
1) Frequency 0, Temperature
Serial number : 03P‐4814
Calibrated on : 14 June 2018
G
: 4.30111327e‐003
H: 6.24737110e‐004
I: 1.86297758e‐005
J: 1.29851757e‐006
F0: 1000.000
Slope: 1.00000000
Offset: 0.0000
2) Frequency 1, Conductivity
Serial number : 04C‐2165
Calibrated on : 23 August 2017G
: ‐9.76338109e+000
H: 1.34212964e+000
I: ‐2.03325982e‐003
J: 2.01310127e‐004
CTcor: 3.2500e‐006
CPcor: ‐9.57000000e‐008
Slope: 1.00000000
Offset: 0.00000
3) Frequency 2, Pressure, Digiquartz with TC
Serial number : 129735
Calibrated on : 3 November 2017
C1
: ‐6.064446e+004
C2: 6.966022e‐002

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C3: 1.971200e‐002
D1: 2.882500e‐002
D2: 0.000000e+000
T1: 3.029594e+001
T2: ‐6.713680e‐005
T3: 4.165390e‐006
T4: 0.000000e+000
T5: 0.000000e+000
Slope: 0.99982000
Offset: ‐1.48930
AD590M: 1.279180e‐002
AD590B: ‐8.821250e+000
4) Frequency 3, Temperature, 2Serial number : 03P‐4816
Calibrated on : 23 August 2017G
: 4.30497192e‐003
H: 6.34223731e‐004
I: 2.17264599e‐005
J: 2.02839765e‐006
F0: 1000.000
Slope: 1.00000000
Offset: 0.0000
5) Frequency 4, Conductivity, 2
Serial number : 04C‐3258
Calibrated on : 25 August 2017G
: ‐1.06581670e+001
H: 1.36071859e+000
I: 1.30128231e‐004
J: 6.09502147e‐005
CTcor: 3.2500e‐006
CPcor: ‐9.57000000e‐008
Slope: 1.00000000
Offset: 0.00000
6) A/D voltage 0, Oxygen, SBE 43
Serial number : 43‐1940
Calibrated on : 21 July 2018
Equation : Sea‐BirdSoc: 5.30300e‐001
Offset: ‐4.97000e‐001
A: ‐3.46500e‐003
B: 1.95130e‐004
C: ‐3.33540e‐006
E: 3.60000e‐002
Tau20: 1.33000e+000
D1: 1.92634e‐004
D2: ‐4.64803e‐002
H1: ‐3.30000e‐002
H2: 5.00000e+003
H3: 1.45000e+003
7) A/D voltage 1, Oxygen, SBE 43, 2
Serial number : 43‐2818
Calibrated on : 24 August 2017
Equation : Sea‐Bird

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Soc: 4.65400e‐001
Offset: ‐4.98300e‐001
A: ‐4.41050e‐003
B: 2.34710e‐004
C: ‐3.56300e‐006
E: 3.60000e‐002
Tau20: 1.38000e+000
D1: 1.92634e‐004
D2: ‐4.64803e‐002
H1: ‐3.30000e‐002
H2: 5.00000e+003
H3: 1.45000e+003
8) A/D voltage 2, Fluorometer, Chelsea Aqua 3
Serial number : 88‐2615‐126
Calibrated on : 16 August 2018
VB
: 0.593340
V1: 2.105980
Vacetone : 0.756140
Scale factor : 1.000000
Slope: 1.000000
Offset: 0.000000
9) A/D voltage 3, Altimeter
Serial number : 62679
Calibrated on : 14 Janusry 2014
Scale factor : 15.000
Offset: 0.000
10) A/D voltage 4, PAR/Irradiance, Biospherical/Licor
Serial number: 70510
Calibrated on: 27 June 2019M
: 1.00000000
B: 0.00000000
Calibration constant : 20300000000.00000000
Multiplier: 1.00000000
Offset: ‐0.05009162
11) A/D voltage 5, PAR/Irradiance, Biospherical/Licor, 2Serial number: 70520
Calibrated on: 27 June 2019M
: 1.00000000
B: 0.00000000
Calibration constant : 19900000000.00000000
Multiplier: 1.00000000
Offset: ‐0.05148773
12) A/D voltage 6, Transmissometer, WET Labs C‐Star
Serial number : CST‐1654DR
Calibrated on : 7 April 2017M
: 21.1627
B: ‐0.1550
Path length : 0.250
13) A/D voltage 7, OBS, WET Labs, ECO‐BB
Serial number : BBRTD‐5466
Calibrated on : 4 February 2019

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ScaleFactor : 0.003307
Dark output : 0.051000
Scan length: 41

LADCP script files:
Casts 001 – 006 (RSMAS)

Master:
WV250
WN25
WS1000
WF0
WB1
EZ0011101
EX00100
WP1
TP 00:00.90
TE 00:00:01.50
CF11101
SM1
SA011
SW5500
RNmast_CKW?
T?
CS
Slave:WV250
WN25
WS1000
WF800
WB1EZ0011101
EX00100
WP1
TP 00:00.00
TE 00:00:01.50
CF11101
SM2
SA011
ST120
RNslav_
CK
W?
T?
CS

; ambiguity velocity [cm/s]; number of depth cells; NBP0402; bin size [cm]; NBP0402: WS1000; blank after transmit [cm]; NBP0402; narrow bandwidth mode
; Sensor source: (NBP0402: EZ0111111); coordinate transformation: (NBP0402: 11111); single‐ping ensembles; NBP0402: WP3 most of the time
; time between pings; NBP0402; time per ensemble; Flow control:; set to master; send pulse before ensemble; master waits .5500 s after sending sync pulse; keep params as user defaults (across power failures); ambiguity velocity [cm/s]; number of depth cells; NBP0402; bin size [cm]; NBP0402: WS1000; blank after transmit [cm]; NBP0402; narrow bandwidth mode
; Sensor source: (NBP0402: EZ0111111); coordinate transformation: (NBP0402: 11111); single‐ping ensembles; NBP0402: WP3 most of the time
; time between pings; NBP0402; time per ensemble; Flow control:; set to slave; waits for pulse before ensemble; waits 120s for ma‐signal before running single^M; keep params as user defaults (across power failures)

Casts 007 – 048 (CTD yo‐yo series) BAS

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Master:
CR1
RN DY108
WM15
TC2
LP1
TB 00:00:02.80
TE 00:00:01.30
TP 00:00.00
LN25
LS0800
LF0
LW1
LV400
SM1
SA011
SB0
SW5500SI0EZ0011101
EX00100
CF11101
CK
CS

Slave:CR1
RN DY108
WM15
LP1
TP 00:00.00
TE 00:00:00.00
LN25
LS0800
LF0
WB1
LW1
LV400
SM2
SA011
SB0
EZ0011101
EX00100
CF11101
CK
CS$l

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7.4.4. SENSOR INFORMATION
7.4.4.1. CTD
SHIP: RRS DISCOVERYCRUISE: DY108/109

FORWARDING INSTRUCTIONS / ADDITIONAL INFORMATION:
Stainless steel 24‐way CTD frame

DATE: 6th September 2019

Checked By: J. Benson

Manufacturer/
Instrument / Sensor

Model

SerialNumberCasts Used
ChannelPrimary CTD deck unit

SBE 11plus

11P‐24680‐
0589

n/a

All casts

CTD Underwater Unit

SBE 9plus

09P‐77801‐1182

n/a

All stainless casts

Stainless steel 24‐way frame

NOCS

SBE CTD 6n/a

All stainless casts

Primary Temperature Sensor

SBE 3P

03P‐4814

F0

All stainless casts

Primary Conductivity Sensor

SBE 4C

04C‐2165

F1

All stainless casts

Digiquartz Pressure sensor

Paroscientific129735F2

All stainless casts

Secondary Temperature Sensor

SBE 3P

03P‐4816

F3

All stainless casts

Secondary Conductivity Sensor

SBE 4C

04C‐3258

F4

All stainless casts

Primary Pump

SBE 5T05T‐3086

n/a

All stainless casts

Secondary Pump

SBE 5T05T‐3090

n/a

All stainless casts

24‐way Carousel

SBE 3232‐60380‐0805

n/a

All stainless casts

Primary Dissolved Oxygen
SensorSBE 4343‐1882

V0

Casts 001‐003

Primary Dissolved Oxygen
SensorSBE 4343‐1940

V0

Casts 004‐048

Secondary Dissolved Oxygen
SensorSBE 4343‐2818

V1

All stainless casts

Fluorimeter

CTG Aquatracka III

88‐2615‐126

V2

All stainless casts

Altimeter

Benthos PSA‐916T

62679

V3

All stainless casts

DWIRR PAR

Biospherical QCP‐
2350‐HP

70510

V4

All stainless casts

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IWIRR PAR

Biospherical QCP‐
2350‐HP

70520

V5

All stainless casts
except 005‐006

Backscatter

WETLabs BBRTD

BBRTD‐5466

V6

All stainless casts

Transmissometer

WETLabs C‐Star

CST‐1654DR

V7

All stainless casts

Downward‐looking 300kHz
Monitor LADCP

TRDI

1855

n/a

All stainless casts

Upward‐looking 300kHz Monitor
LADCP

TRDI

4275

n/a

All stainless casts

LADCP battery pack

NOCS

WH007

n/a

Casts 001‐026

LADCP battery pack

NOCS

n/a

Casts 027‐048

n/a

All stainless casts

WH007
6T

10L Water Samplers

Ocean Test
Equipment

1B‐24B

7.4.4.2. Lowered Acoustic Doppler Current Profiler (LADCP) –Instrument and Configuration
For all CTD casts, two RDI 300kHz Workhorse LADCP units were fitted to the CTD
frame one in a downward‐looking orientation the other upward‐looking. Each LADCP
was configured to have 25 x 8 m bins, a 0 m blank‐to‐surface, one ping per ensemble, and two
ensembles per burst in narrowband mode. Data were collected in beam coordinates.
Parameter Description:
WM15 water mode 15 (LADCP)
TC2 ensembles per burst
LP1 pings per ensemble
TB 00:00:02.80 time per burst
TE 00:00:01.30 time per ensemble
TP 00:00.00 time between pings
LN25 number of depth cells
LS0800 bin size [cm]
LF0 blank after transmit [cm]
LW1 narrow bandwidth LADCP mode
LV400 ambiguity velocity [cm/s]
SB0 disable hardware‐break detection on Channel B (ICN118)
EZ0011101 Sensor source: ‐ manual speed of sound (EC)‐ manual depth of transducer (ED = 0 [dm]) ‐measured heading (EH) ‐ measured pitch (EP) ‐ measured roll (ER) ‐ manual salinity (ES = 35 [psu]) ‐measured temperature (ET)EX00100 Coordinate transformation: ‐ radial beam coordinates (2 bits) ‐ use pitch/roll (not used forbeam coords?) ‐ no 3‐beam solutions – no bin mapping
CF11101 Flow control: ‐ automatic ensemble cycling (next ens when ready) ‐automatic ping cycling(ping when ready) ‐ binary data output‐ disable serial output ‐ enable data recorder

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7.5. Mooring
Operational Team: Billy Platt
The mooring, as described in section 6.6.4 was deployed over the aft end of the Discovery by handand is as per the mooring diagram in Fig. 6.84. After triangulation the final position of the mooring
was confirmed to be 59 deg 51.672 N, 007 deg 02.631 W.
Prior to deployment the Ixsea release was tested down to a depth of 1800m and worked correctly.
7.5.1. SBE37
The SBE 37’s were attached to the CTD for a test dip to ensure that they were working fine. The data
was checked by the science party, compared to the CTD data and deemed to be good. Both were setup
for deployment using the following commands.
datetime=MMDDYYYYHHMMSS
outputformat=3
txrealtime=noutputsal=y
sampleinterval=900
samplenumber=0
samplenumber=0
startdatetime=startnow
qs

7.5.2. ADCP 600KHz Workhorse Sentinel
Sn 23184 fitted downward looking in a 44” syntactic sphere, Sn J17041‐001 along with Light Sn A08‐
011 and Argos Sn A02‐017.
Downlooking 600 kHz ADCP
Duration: 365 days
Ensemble interval: 00:01:30
Ping interval 00:00:05
Pings per ensemble: 10
Depth cell size: 1 m (30 m range)

7.5.3. Sediment trap
Sn 12168‐02
21 bottle trap programmed with the science party as described in Section 6.6.4.

7.5.4. Instrument Log

SBE 37’sds
SBE37SM‐RS232 v4.1 SERIAL NO. 12456 23 Sep 2019 07:16:30
vMain = 13.14, vLith = 2.97
samplenumber = 0, free = 559240
logging
sample interval = 900 seconds
data format = converted engineering

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transmit real‐time = nosync mode = nopump installed = yes, minimum conductivity frequency = 3073.6<Executed/>ds
SBE37SM‐RS232 v4.1 SERIAL NO. 12458 23 Sep 2019 07:17:29
vMain = 13.36, vLith = 3.00
samplenumber = 0, free = 559240
not logging, stop command
sample interval = 900 seconds
data format = converted engineeringtransmit real‐time = nosync mode = nopump installed = yes, minimum conductivity frequency = 3110.7<Executed/>
startnow<!‐‐start logging at = 23 Sep 2019 07:32:47, sample interval = 900 seconds‐‐><Executed/>ds
SBE37SM‐RS232 v4.1 SERIAL NO. 12458 23 Sep 2019 07:17:48
vMain = 13.35, vLith = 3.00
samplenumber = 0, free = 559240
logging
sample interval = 900 seconds
data format = converted engineeringtransmit real‐time = nosync mode = nopump installed = yes, minimum conductivity frequency = 3110.7<Executed/>

ADCP
CR1
CF11101
EA0
EB0
ED0
ES35
EX11111
EZ1111101
WA50
WB0
WD111100000
WF88
WN29
WP10
WS100
WV175

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TE00:01:30.00
TP00:09.00
TF19/09/23 07:00:00
CK
CS;;Instrument= Workhorse Sentinel;Frequency= 614400;Water Profile = YES;Bottom Track= NO;High Res. Modes = NO;High Rate Pinging = NO;Shallow Bottom Mode= NO;Wave Gauge= NO;Lowered ADCP
= NO
;Ice Track= NO;Surface Track = NO
;Beam angle= 20;Temperature= 5.00;Deployment hours = 9600.00;Battery packs = 2;Automatic TP= YES;Memory size [MB] = 3900
;Saved Screen=2;;Consequences generated by PlanADCP version 2.06:;First cell range = 2.10 m;Last cell range = 30.10 m;Max range= 42.01 m;Standard deviation = 2.21 cm/s
;Ensemble size = 734 bytes;Storage required = 268.80 MB (281856000 bytes);Power usage= 829.88 Wh;Battery usage = 1.8;; WARNINGS AND CAUTIONS:; Advanced settings have been changed.

Sediment trap
Schedule Verification
Event 1 of 22 = 09/24/2019 12:00:00
Event 2 of 22 = 10/12/2019 12:00:00
Event 3 of 22 = 10/30/2019 12:00:00
Event 4 of 22 = 11/17/2019 12:00:00
Event 5 of 22 = 12/05/2019 12:00:00
Event 6 of 22 = 12/23/2019 12:00:00
Event 7 of 22 = 01/10/2020 12:00:00

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Event 8 of 22 = 01/28/2020 12:00:00
Event 9 of 22 = 02/15/2020 12:00:00
Event 10 of 22 = 03/04/2020 12:00:00
Event 11 of 22 = 03/22/2020 12:00:00
Event 12 of 22 = 04/09/2020 12:00:00
Event 13 of 22 = 04/27/2020 12:00:00
Event 14 of 22 = 05/15/2020 12:00:00
Event 15 of 22 = 06/02/2020 12:00:00
Event 16 of 22 = 06/20/2020 12:00:00
Press any key to continue.
Event 17 of 22 = 07/08/2020 12:00:00
Event 18 of 22 = 07/26/2020 12:00:00
Event 19 of 22 = 08/13/2020 12:00:00
Event 20 of 22 = 08/31/2020 12:00:00
Event 21 of 22 = 09/18/2020 12:00:00
Event 22 of 22 = 10/06/2020 12:00:00
09/22/2019 15:31:32 18.7 Vb 18 øC aligned

Cruise report No. 66

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7.6. Ship‐fitted Systems
Operational team: Martin Bridger
7.6.1. Scientific Computer Systems
7.6.1.1. Acquisition
Network drives were set up on the on‐board file server; firstly a read‐only drive of the ship’s
instruments data (‘current_cruise’) and a second drive (‘Public’) for the scientific party. Both drives
have been backed up on external disks, and have been provided to the co‐chief scientists of the cruise.
The data back‐ups have also been transferred to the British Oceanographic Data Centre (BODC) who
will archive the cruise data for NERC, and who will make the data available to interested scientists(following agreement by the cruise PIs).
Data was logged by the Techsas 5.11 data acquisition system. The system creates NetCDF and ASCII
output data files located in the below ‘TechSAS’ directory. The format of the data files is given per
instrument in the “Data Description” directory:
Cruise Disk Location: ‘DY108/Cruise_Documentation/Data_Description_Documents/’‘DY108/Ship_Fitted_Scientific_Systems/TechSAS’

The Ship‐fitted instruments that were logged are listed in Table 7.30.
The NMF ‘RVDAS’ raw data logger also records raw data streams as a backup/QC option to theprimary Techsas logger. These raw ASCII files are located in the below cruise directory:

Cruise Disk Location: ‘DY108/Ship_Fitted_Scientific_Systems/RVDAS’

Data was additionally logged into the legacy RVS Level‐C format.
There are ASCII dumps of all the Level‐C streams included on the data disk in the directory:
Cruise Disk Location: ‘DY108/Ship_Fitted_Scientific_Systems /Level‐C/Enterprise‐pro_data/ascii/’

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Table 7.30 Ship‐fitted instrumentation and logging status for DY108/109
Manufacturer

Model

Function/data types

Logged?

Comments(Y/N)
Meinberg

M300

GPS network time server
(NTP)

N

Applanix

POS MV320 V5

DGPS and attitude

Y

C-Nav

3050

DGPS and DGNSS

YKongsberg Seatex

Seapath 330

DGPS and attitude

Y

iXSea

PHINSIII

Inertial Navigation System

N

Sonardyne

Fusion USBL

USBL

Y

Ship gyrocompasses x 3

YSingle beam echo sounder(hull)
Multibeam echo sounder(deep)
Multibeam echo sounder(shallow)
Sub bottom profiler

YN

Sperry Marine
Kongsberg Maritime

Simrad EA640

Kongsberg Maritime

Simrad EM122

Kongsberg Maritime

Simrad EM710

Kongsberg Maritime

Simrad SBP120

Kongsberg Maritime

Simrad EK60

NMFSS

CLAM

Scientific echo sounder(fisheries)
CLAM system winch log

NMFSS

Surfmet

Meteorology suite

Y

NMFSS

SurfmetSurface hydrography suite

Y

Skipper log (ship’s velocity)Y

Not logged but
feeds times toother systems
Secondary DGPS
Primary DGPS
LoggedNo attitude logged,
only position

Y
Y
Y

Y

OceanWaveS GmbHWaMoS II

Wave RadarN

Teledyne RD
Instruments
Teledyne RD
Instruments
Microg Lacoste

Ocean Observer
75 kHz
Ocean Observer
150 kHz
Air-Sea System II

VM-ADCPY

VM-ADCPY

GravityN

7.6.1.1.1 Main Acquisition Period
Techsas logging for ‘DY108’ commenced on 06/09/2019 whilst alongside in Southampton. RVDAS
logging commenced 10:28 on 05/09/2019.
All logging was concluded upon arrival in Southampton 2nd October 2019.
7.6.1.1.2 Events/Data Losses
No known data losses occurred.

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7.6.1.2. Communications
7.6.1.2.1 Internet provision
Satellite Communications were provided with both the Vsat and Fleet Broadband (FBB) systems. The
Vsat had a guaranteed speed of 1.5 Mbps, bursts greater than this when there is space on the satellite,
and unlimited data. The FBB had a maximum un‐guaranteed speed of 256 kbps with a fair use policythat equates to 15 GB of data a month. There was solid service throughout, interrupted with a few
mast blockages.
7.6.1.2.2 Email provision
Email communications were provided primarily through user email clients and web‐browser clients.

7.6.2. Instrumentation
7.6.2.1. Marine Mammal Protection
All acoustic instruments were operated in accordance with JNCC / NERC Marine Mammal protection
guidelines. To ensure compliance, a member of the science party (H.Hinchen from JNCC), who had
attended the necessary training, was involved in all acoustic operations. They also offered guidance
to avoid any detrimental effect on the marine life due to inappropriate use of acoustic equipment.

7.6.2.2. Coordinate reference Datum
The common coordinate reference was defined by the Parker Maritime survey (2013) as:
1.

The reference plane is parallel with the main deck abeam (transversely) and with the baseline(keel) fore‐ and aft‐ways (longitudinally).

2.

Datum (X = 0, Y = 0, Z = 0) used in all systems is that of the coordinate reference system 2 with
CRP at CG.

Multibeam
The Kongsberg axes reference conventions are (see Fig. 7.36) as follows:1.

X positive forward,

2.

Y positive starboard,3.

Z positive downward.

The roll reference is set to follow the convention of Applanix PosMV.
The translations and rotations provided by the Applanix PosMV Primary scientific position and attitude
system have the following convention:
1.

Roll positive port up,

2.

Pitch positive bow up,

3.

Heading true,

4.

Heave positive up.

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X positive forward,
Roll positive port up.
Heave positive up.

Datum CGY positive starboard,
Pitch positive bow up.

Kongsberg Z positive down.

Fig. 7.36 Conventions used for position and attitude.

7.6.2.3. Position and Attitude
GPS and attitude measurement systems were run throughout the cruise.
7.6.2.3.1 Applanix POSMVThe Applanix POSMV system is the vessel's primary scientific GPS system, outputting the position of
the ship's common reference point in the gravity meter room (Refer to Parker Report, 2013 –Enclosure 3/Coordinate System 2). The POSMV is available to be sent to all scientific systems and isrepeated around the vessel. The position fixes, attitude and gyro data are logged to the Techsas
system.
The POSMV was the position and attitude source used by the EM122/EM710 as appropriate during
this cruise.
7.6.2.3.2 Kongsberg Seapath 330
The Kongsberg Seapath 300 system is the vessel’s secondary GPS system. It provides an input to theGravity meter due to the POSMV not having vessel course available in its RMC NMEA message.
Position fixes and attitude data is logged to the Techsas system.
Due to faults with the Seapath developed on the previous cruise resulting in occasional large HDOP
values, data from this system should be treated with caution.
7.6.2.3.3 C‐NAV 3050
The CNav 3050 GPS system is a differential correction service. It provides the Applanix POSMV systemwith RTCM DGPS corrections (greater than 1m accuracy). The position fixes data are logged to theTechsas system.
7.6.2.3.4 Fugro Seastar 9205
The Fugro Seastar 9205 GPS system is a differential correction service. It provides the Seapath systemwith RTCM DGPS corrections. Fugro NMEA output messages are logged to the Techsas system.

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7.6.2.4. Meteorology and sea surface monitoring package
The NMF Surfmet system was run throughout the cruise, excepting times for cleaning, entering andleaving port, and whilst alongside. Please see the separate information sheet for details of the sensors
used and whether calibrations values have been applied:‘DY108_Surfmet_sensor_information_sheet.docx’
Cruise Disk Location: ‘DY108/Ship_Fitted_Scientific_Systems/Surfmet/’
Seawater is taken in at a depth of 5.5m, and pump rate was 20,000ml/min (pre‐debubbler), 1750
ml/min (instrumentation).
The Surfmet system is comprised of (see also Table 7.31 and Fig. 7.37):
1.

Hull water inlet temperature probe (SBE38).

2.

Sampling board conductivity, temperature salinity sensor (SBE45).

3.

Sampling board transmissometer (CST).

4.

Sampling board fluorometer (WS3S)

5.

Met platform temperature and humidity probe (HMP45).

6.

Met platform port and starboard ambient light sensors (PAR, TIR).

7.

Met platform atmospheric pressure sensor (PTB110).

8.

Met platform anemometer (Windsonic).

Table 7.31 details of fitted sensors on the Surfmet system during DY108/109
Manufacturer

SensorSerial No

Comments

Calibration
applied?

AML

Micro‐X Surface
SV
PAR SKE510
PAR SKE510
TIR CM6B
TIR CM6B
Windsonic
Option 310377/203551

Drop Keel SV

Y

28560
48927
99413297313410280018

N
N
N
N
N

01/05/2018
30/01/2018
18/10/2018
18/10/2018
N/A (tested
28/09/2015)

HMP155
Temp./Hum.
PTB210 Air Pres.
WS3S
Fluorimeter
CST
Transmissometer
SBE45 TSG

N1211119Starboard
Port
Starboard
Port
Starboard
Inv:
250006705
260004820

N

22/10/2018

260004687

NN

19/10/2018
24/10/2018

N

19/03/2018

N

27/06/2019

SBE38
Temperature

3854115‐0487

N

26/06/2019

Skye
Skye
Kipp & Zonen
Kipp & Zonen
Gill

Vaisala
Vailsala
Wet Labs
Wet Labs
Sea‐Bird
Sea‐Bird

Cruise report No. 66

N093256
WS3S‐134
CST‐1852PR
4548881‐0230

Installed
05/09/2019
Installed
05/09/2019

Last
calibration(DD/MM/YY)
03/04/2019

Page 204 of 224

Fig. 7.37 Configuration of the DY108 Met Platform

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Instrument calibration sheets are included in the directory:
Cruise Disk Location:‘DY108/ Ship_Fitted_Scientific_Systems/Surfmet/SurfMet_Calibration_sheets/’

7.6.2.4.1

Underway TSG Data

Table 7.32 Overview of water samples taken from the Surfmet package

Crate

Bottle
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4

Date
97
98
99
100
101
102
103
104
105
106
111
112
107
108
109
110

2019‐09‐16
2019‐09‐16
2019‐09‐17
2019‐09‐17
2019‐09‐20
2019‐09‐20
2019‐09‐22
2019‐09‐22
2019‐09‐23
2019‐09‐23
2019‐09‐25
2019‐09‐25
2019‐09‐26
2019‐09‐26
2019‐09‐27
2019‐09‐27

Time start Time end
TSG salinity
15:39:00
15:39:00
35.223929
15:39:00
15:40:00
35.223929
13:22:00
13:23:00
35.202884
13:22:00
13:23:00
35.202884
08:54:00
08:55:00
35.196755
08:54:00
08:55:00
35.196755
08:58:00
08:59:00
35.203968
08:58:00
08:59:00
35.203968
08:25:00
08:26:00
35.190874
08:25:00
08:26:00
35.190874
11:10:00
11:11:00
35.188768
11:10:00
11:11:00
35.188768
13:23:00
13:24:00
35.156802
13:23:00
13:24:00
35.156802
11:12:00
11:13:00
35.209274
11:12:00
11:13:00
35.209274

The collected water samples were measured for salinity using a Guildline Autosal 8400B salinometer.
These results and a comparison with SBE45 TSG salinity values (averaged over 30 seconds before
sample and 30 seconds after sample) are in the directory below:

Cruise Disk Location: ‘DY108/Ship_Fitted_Scientific_Systems/Surfmet/tsg_salinities’

7.6.2.5. Drop Keel Sound Velocity Sensor
The surface Sound Velocity (SV) sensor (AML SmartSV) mounted on the drop keel was used throughout
providing SV data to the EM122/EM710. The port drop keel remained flush with the hull for theduration of the cruise.

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7.6.2.6. Kongsberg EA640 10 & 12 kHz Single‐beam
The EA640 single‐beam echo‐sounder was run throughout the cruise. Both 12 and 10kHz were used.
Pulse parameters were altered during the cruise in response to changing depth. This depth was usedas the input for the CLAM (Cable Logging and Measurement) during deployment activities.
The system used a constant sound velocity of 1500 ms‐1 throughout the water column to allow it tobe corrected for sound velocity in post processing if required. Salinity (35 PSU) and Temperature(10degreeC) and Conditions (salt water) were also left as constant values for the cruise duration.
Kongsberg *.raw files (~100MB file size) and *.xyz files are logged and depths were logged to Techsas,
Level‐C and RVDAS.

7.6.2.7. Kongsberg SBP120 Sub Bottom Profiler
This system was run during the cruise, both RAW and SEGY formats were recorded (see also Section
6.1).

Cruise Disk Location: ‘DY108/Ship_Fitted_Scientific_Systems/Acoustics/SBP120

7.6.2.8. ADCP OS75KHz (RDI Teledyne).
The RDI Teledyne Ocean Surveyor 75KHz ADCP was configured as per DY107 trials cruise. It was run
continuously, controlled, and logged by UHDAS. During the passage to the work area both systems
were set to bottom track. Once enough bottom track data was collected, they were switched to hybrid
Wideband/Narrowband mode.

Cruise Disk Location: ‘DY108/Ship_Fitted_Scientific_Systems/Acoustics/ADCP‐UHDAS

Data Feeds


GGA (Ship Position) and VTG (Ship Speed) was provided by the Applanix POS‐MV.



Heading and Tilt was provided by the iXSea PHINS MRU (PRDID NMEA message).

7.6.2.9. ADCP OS150KHz (RDI Teledyne).
The RDI Teledyne Ocean Surveyor 150KHz ADCP was configured as per DY107 trials. It was run
continuously, controlled, and logged by UHDAS. During the passage to the work area both systems
were set to bottom track. Once enough bottom track data was collected, they were switched to hybrid
Wideband/Narrowband mode.

Cruise Disk Location: ‘DY108/Ship_Fitted_Scientific_Systems/Acoustics/ADCP‐UHDAS

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Data Feeds


GGA (Ship Position) and VTG (Ship Speed) was provided by the Applanix POS‐MV.



Heading and Tilt was provided by the iXSea PHINS MRU (PRDID NMEA message).

7.6.2.10. Kongsberg EM122 Multibeam Echo Sounder
The EM122 multibeam echo sounder was run throughout the cruise. The position and attitude data
were supplied from the Applanix PosMV and True Heave *.ath file are logged to allow for inclusion
during reprocessing.
Sound velocity profiles were obtained from CTD casts using the Chen and Millero formula as this is themost appropriate for shelf work <1000m (Ref. Valeport) and compares very well against the Midas
SVP profile (ref. DY100). These were entered into SIS after converting the files using the SVP editor.
Figs. 7.38 & 7.39 show the system installation configuration. The values are from the ships Parker
survey report, which is included on the data disk.

Fig. 7.38 – EM122 transducer locations

Fig. 7.39 – EM122 transducer offsets

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Cruise Disk Location: ‘DY108/Ship_Fitted_Scientific_Systems/Acoustics /EM122/’

7.6.2.11. Kongsberg EM710 Multibeam Echo Sounder
The EM710 multibeam echo sounder was used during shallow water surveys, e.g. during transits. The
position and attitude data was supplied from the Applanix PosMV and True Heave *.ath file are logged
to allow for inclusion during reprocessing.
Sound velocity profiles were obtained from CTD casts, and entered into SIS after converting the files
using the SVP editor.
Figs. 7.40 & 7.41 show the system installation configuration. The values are from the ships Parker
survey report, which is included on the data disk.

Fig. 7.40 – EM710 transducer locations

Fig. 7.41 – EM710 transducer offsets

Cruise Disk Location:‘DY108/Ship_Fitted_Scientific_Systems/Acoustics /EM710/’

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7.6.2.12. Multibeam CARIS Processing
Processing using CARIS HIPS&SIPS was undertaken by the scientific party, and is explained in Section
6.1.

7.6.2.13. Sound velocity profiles

Cruise Disk Location:‘DY108/Ship_Fitted_Scientific_Systems/Acoustics/Sound_Velocity_Profiles/

7.6.2.14. Sonardyne USBL
The starboard head was used as this gave the widest angular range. The calibration offsets wereentered into System 1 (USBL1 on Blackbox) and this was used throughout the cruise.
System 1 : Port pole : Pitch=0.489, roll=0.187, heading=0.345
System 2 : Starboard pole : Pitch=0.262, roll=0.129, heading=0.761

USBL beacons used:
SandM WMT beacon was used for Autosub missions. Its address was changed to 3004, and power set
to maximum to make it the same as SSS beacon 3003. After several long deployments, and being
charged between deployments, the AUV team returned the beacon with a flat battery. This exhibited
similar charging issues that befell our WMTs earlier this year, except it was still possible tocommunicate with the beacon. Swapping batteries with our known good (new) spare, did not work,and the beacon reported that the battery was only about 10% charged. During charging, the brown
disk (thermal fuse possibly?) got very hot. The software reported temperatures in excess of 30C while
the beacon was on the bench in pieces, with battery connected but not actually fitted in the unit.
SandM are going to have to send their beacon back to Sonardyne for evaluation.
WMT 3003 was used for the remainder of Autosub missions without problems.
Both WSM beacons were used for coring QsY2 was used mainly.
Both WSM beacons were used alternately for 2 x 24 hour Yoyo deployment, swapping the beacon
between deployments. The WSM beacons worked well throughout.

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8. REFERENCES
Bett, B.J., 1999. RRS Charles Darwin Cruise 112C, 19 May‐24 Jun 1998. Atlantic Margin Environmental
Survey: seabed survey of deep‐water areas (17th round Tranches) to the north and west of
Scotland. Southampton, UK, Southampton Oceanography Centre, 171pp. (Southampton
Oceanography Centre Cruise Report, No. 25)
Bett (2001). UK Atlantic Margin Environmental Survey: Introduction and overview of bathyal benthic
ecology. Continental Shelf Research, 21: 917‐956.
Bett, B.J., 2007. RRS Charles Darwin Cruise 123C3‐4, 19 Jul‐15 Sep 2000. Atlantic Margin Environmental
Surveys and North Sea Surveys. Southampton, UK: National Oceanography Centre,
Southampton, 221pp. (National Oceanography Centre Southampton Cruise Report, No. 20)
Bett, B.J.; Billett, D.S.M.; Masson, D.G.; Tyler, P.A., 2001 RRS Discovery Cruise 248, 07 Jul‐10 Aug 2000.
A multidisciplinary study of the environment and ecology of deep‐water coral ecosystems andassociated seabed facies and features (The Darwin Mounds, Porcupine Bank and Porcupine
Seabight). Southampton, UK, Southampton Oceanography Centre, 108pp. (Southampton
Oceanography Centre Cruise Report 36)
Bett, B.J., Jacobs, C.L., 2007. 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. Southampton, UK: National Oceanography Centre, Southampton, 120pp. (National
Oceanography Centre Cruise Southampton Cruise Report, No. 19)
Bodenmann, A., Thornton, B., and Ura, T. (2017): “Generation of high‐resolution three‐dimensional
reconstructions of the seafloor in colour using a single camera and structured light,” Journalof Field Robotics 34 (5), 833–851.
Booth, D.A. & Ellett, D.J. (1983). The Scottish continental slope current. Continental Shelf Research, 2(2/3): 127‐146.
Davies, A. J., et al. (2007). "Preserving deep‐sea natural heritage: emerging issues in offshore
conservation and management." Biological Conservation 138: 299‐312.
De Santo, E. and P. J. S. Jones (2007). "Offshore marine conservation policies in the North East
Atlantic:emerging tensions and opportunities." Marine Policy 31: 336‐347.
Gubbay, S., C. M. Baker, and B. J. Bett. 2002. The Darwin Mounds and the Dogger Bank, case studiesof the management of two potential Special Areas of Conservation in the offshore
environment. WWF‐UK, Surrey. 72 p
Howell, K.L. & Taylor, M. (2016). Deep Links project. RRS James Cook Cruise No. JC136. University of
Plymouth Cruise Summary Report. 150p
Gage, J.D., Bett, B.J., 2005. Deep‐sea benthic sampling. In: Eleftheriou, A., McIntyre, A., (eds.) Methods
for the study of marine benthos, 3rd ed. Oxford, UK, Blackwell Science, 273‐325, 418pp.
Garrett, C. & Munk, W. (1972). Oceanic mixing by breaking internal waves. Deep‐Sea Research, 19:
823‐832.
Holliday, N.P., Pollard, R.T., Read, J.F. & Leach, H. (2000). Water mass properties and fluxes in the
Rockall Trough, 1975‐1998. Deep‐Sea Research I, 47:1303‐1332.

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Hughes, J. A. and A. J. Gooday (2004). "Associations between living benthic foraminifera and deadtests of Syringammina fragilissima (Xenophyophorea) in the Darwin Mounds region (NEAtlantic)." Deep‐Sea Research I 51(11): 1741‐1758.
Huvenne, V. A. I. (2011). RRS James Cook Cruise 60, 09 May‐12 June 2011. Benthic habitats and theimpact of human activities in Rockall Trough, on Rockall Bank and in Hatton Basin. Cruise
Reports. N. O. Centre. Southampton, National Oceanography Centre, Southampton: 133.
Huvenne, V. A. I., et al. (2016). "Effectiveness of a deep‐sea cold‐water coral Marine Protected Area,
following eight years of fisheries closure." Biological Conservation 200: 60‐69.
Johnson, C., Sherwin, T., Smythe‐Wright, D., Shimmield, T. & Turrell, W. (2010). Wyville Thomson Ridge
Overflow Water: spatial and temporal distribution in the Rockall Trough. Deep‐Sea ResearchI, 57: 1153‐1162.
Johnson, C., Inall, M. and Häkkinen, S., 2013. Declining nutrient concentrations in the northeast
Atlantic as a result of a weakening Subpolar Gyre. Deep Sea Research Part I: Oceanographic
Research Papers, 82, pp.95‐107.
Johnson‐Roberson, M., Pizarro, O., Williams, S., and Mahon, I. (2010): “Generation and visualizationof large‐scale three‐dimensional reconstructions from underwater robotic surveys,” Journalof Field Robotics, 27(1):21‐51.
Johnston, C. M., C. G. Turnbull, and M. L. Tasker. 2001. Natura 2000 in UK offshore waters: advice tosupport the implementation of the EC Habitats and Birds Directives in UK offshore waters,
Report 325. JNCC, Peterborough. 162 p.
Masson, D.G.; Jacobs, C.L., 1999 RV Colonel Templer Cruises 01 & 02/98, 22 Apr‐18 Jun 1998. TOBI
surveys of the continental slope north and west of Scotland. Southampton, UK, Southampton
Oceanography Centre, 66pp. (Southampton Oceanography Centre Cruise Report, No. 22
Masson et al. (2003). The origin of deep‐water, coral‐topped mounds in the northern Rockall Trough,Northeast Atlantic. Marine Geology, 194: 159‐180.
McKenna, C., Berx, B. and Austin, W.E.N., 2016. The decomposition of the Faroe‐Shetland Channelwater masses using Parametric Optimum Multi‐Parameter analysis. Deep Sea Research Part I:
Oceanographic Research Papers, 107, pp.9‐21.
Narayanaswamy, B.E., Bett, B.J., Lamont, P.A., Rowden, A.A., Bell, E.M. and Menot, L. (2016). Corers
and Grabs. In: M.R. Clark, M. Consalvey and A.A. Rowden (eds.) Biological Sampling in the
Deep Sea. Hoboken, New Jersey : Wiley‐Blackwell. doi:10.1002/9781118332535.ch10
Roche, M., Degrendele, K., Vrignaud, C., Loyer, S., Le Bas, T., Augustin, J., and Lurton, X. (2018) Controlof the repeatability of high frequency multibeam echosounder backscatter by using naturalreference areas. Mar Geophys Res (2018) 39: 89. https://doi.org/10.1007/s11001‐018‐9343‐
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UNGA, 2006. Resolution 61/105. Sustainable Fisheries, Including through the 1995 Agreement for the
Implementation of the Provisions of the United Nations Convention on the Law of the Sea of
10 December 1982 Relating to the Conservation and Management of Straddling Fish Stocks
and highly Migratory Fish Stocks, and Related Instruments, United Nations. p. 21.
Victorero, L., et al. (2016). "Reconstruction of the formation history of the Darwin Mounds, N Rockall
Trough: how the dynamics of a sandy contourite affected cold‐water coral growth." Marine
Geology 378: 186‐195.

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Wheeler et al. (2005). The impact of demersal trawling on northeast Atlantic deepwater coral habitats:
The case of the Darwin mounds, United Kingdom. American Fisheries Society Symposium, 41:
807‐818.
Yamada, T., Thornton, B., and Prugel‐Bennet, A. (in preparation) Learning using autoencoders for
unsupervised classification and query of seafloor imagery

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9.

STATION LIST

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10. MAPS
General cruise track:

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New shipboard bathymetry data collected in the Darwin Mounds area

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Processed new sidescan sonar data of the Western Darwin Mounds

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Processed new sidescan sonar data for the Eastern Darwin Mounds

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DY108/109 station locations for CLASS Ellett Line work

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DY108/109 Stations in the Darwin Mound area

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Stations and HyBIS dive tracks in the Eastern Darwin Mounds, over AUV sidescan sonar data from JC060

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Stations and HyBIS dive tracks in the Western Darwin Mounds, over AUV sidescan sonar data from the current cruise (front) and from JC060 (background)

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CTD stations for BLT‐Recipes. Background bathymetry provided by INFOMAR programme

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