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RRS Charles Darwin CD176

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS Charles Darwin (74AB)
Cruise identifierCD176
Cruise period2005-10-06 — 2005-11-01
StatusCompleted
Port of departureBirkenhead, United Kingdom
Port of returnFalmouth, United Kingdom
PurposeResearch
ObjectivesThe principle objective of the cruise was to undertake the sampling of the Extended Ellett Line a section of CTD and biochemical monitoring stations that run from Ardnamurchan Point in Scotland to Rockall and on to Iceland, ending close to the volcanic island of Surtsey. Secondary objectives included making trace metal observations with a view to i) an investigation of circulation in the Rockall Trough and ii) researching the limiting role of iron in biological production in the Iceland Basin, investigating cetacean distributions and undertaking coring activities. In addition the cruise provided training and data for 5 PhD students on board and one, Clare Johnson, who was unable to join the ship. The Ellett Line is a vitally important section that provides data to monitor the state of the North Atlantic. In all 66 oceanic CTD stations were occupied. Although a significant amount of downtime was encountered - mainly due to bad weather - the cruise was nevertheless very successful. It completed the section from Scotland to Rockall, an ADCP mooring was laid in the gully leading away from the Wyville Thomson Ridge (the Ellett gully) which was mapped in detail; iron incubation measurements were made with water from the Iceland Basin; a large number of sperm whales and dolphins were heard in the Rockall Trough; the presence of acorn worms in the muds at the bottom of the Faroe-Shetland Channel was confirmed. In addition nearly all the CTD and underway sensors performed satisfactorily, and in particular the oxygen sensor on the stainless steel CTD performed very well. After much work on a neglected system on board the Charles Darwin the vessel mounted ADCP gave good data. And on the final leg home we carried out a very detailed survey of the water quality just above the Migulay cold water coral reef. Given the potential for bad weather as this time of year a large amount work was achieved. No group achieved all its objectives, but neither did any one come away empty handed
Chief scientistToby J Sherwin (Scottish Association for Marine Science)
ProjectNorthern Seas Programme
Coordinating bodySAMS/NOCS
Cruise reportRRS Charles Darwin CD176 cruise report cd176.pdf (2.81 MB) 
Ocean/sea areas 
GeneralInner Seas off the West Coast of Scotland
North East Atlantic Ocean (limit 40W)
SpecificMalin Shelf; Rockall Trough; Rockall Bank; Iceland Basin, Wyville Thomson Ridge, Faroe-Shetland Channel
Track chartsRRS Charles Darwin CD176 cruise track — cd176trk.pdf (0.05 MB) 
Measurements 
Physical oceanography 
Surface measurements underway (T,S)Quantity: track kilometres = 3148.4
Description: Continuous underway Sea Temp, Salinity, ADCP, Tranmissometer, Fluorometer
CTD stationsQuantity: number of stations = 66
Description: Continuous profiles of pressure, temperature, conductivity, LADCP (up and down), fluorometer, dissolved oxygen, transmissometer
Chemical oceanography 
OxygenQuantity: number of samples = 600
Description: Oxygen profiles
PhosphateQuantity: number of samples = 153
Description: Underway phosphate
PhosphateQuantity: number of samples = 400
Description: Phosphate profiles
NitrateQuantity: number of samples = 153
Description: Underway nitrate
NitrateQuantity: number of samples = 400
Description: Combined NO2, NO3 profiles
NitriteQuantity: number of samples = 100
Description: Near surface nitrite profiles
AmmoniaQuantity: number of samples = 400
Description: Ammonium profiles
SilicateQuantity: number of samples = 153
Description: Underway silicate
SilicateQuantity: number of samples = 400
Description: Silicate profiles
pHQuantity: number of samples = 400
Description: pH profiles
Other chemical oceanographic measurementsQuantity: number of samples = 16
Description: Dissolved iron profiles (Iceland Basin only)
Other chemical oceanographic measurementsQuantity: number of samples = 300
Description: Dissolved and particulate aluminium profiles (E of 15 W only)
Other chemical oceanographic measurementsQuantity: number of samples = 153
Description: Underway surface dissolved iron samples
Biology and fisheries 
Particulate organic matter (inc POC, PON)Quantity: number of samples = 400
Description: POC profiles
Mammals and reptilesQuantity: number of deployments = 27
Description: Hydrophones deployed at some CTD stations to detect baleen whales (not in Icelandic waters)
Mammals and reptilesQuantity: track kilometres = 1500
Description: Acoustic monitoring for sperm whales and dolphins (not in Icelandic waters)
Other biological/fisheries measurementQuantity: number of experiments = 2
Description: Bioassay incubations involving dissolved Fe, nutrients, Chl A, HPLC, POC, PON, Lugols, FRRF (phytoplankton physiology). Iceland Basin and Rockall Trough
Meteorology 
Routine standard measurementsQuantity: track kilometres = 3148.4
Description: Continuous underway Air temp, atmospheric pressure, port and starboard PAR, port and starboard TIR, wind speed and direction
Geology and geophysics 
Core - soft bottomQuantity: number of cores = 7
Description: Megacore (either side of Wyville Thomson Ridge)
Core - soft bottomQuantity: number of cores = 3
Description: Box core (Faroe-Shetland Channel)
Multi-beam echosoundingQuantity: number of surveys = 4
Description: Swath bathymetry - parts of: Wyville Thomson Ridge, Hatton Bank, Rockall Bank, George Bligh Bank
Moorings, landers, buoys 
Physical oceanography 
Current profiler (eg ADCP)60° 14' 21" N  8° 52' 11" W — 1 Broadband ADCP 16 Oct 2005 (Ellett gully ADCP)
Neutrally buoyant floats61° 15' 42" N  20° 0' 47" W — 1 Argo float 19 Oct 2005
Data held at BODC Get data
Discrete samples 
3  Box core
66  CTD frame plus rosette samplerAmmonium and ammonia concentration parameters in water bodies
Particulate total and organic carbon concentrations in the water column
Particulate total and organic nitrogen concentrations in the water column
Chlorophyll pigment concentrations in water bodies
Silicate concentration parameters in the water column
Salinity of the water column
Nitrate concentration parameters in the water column
Phosphate concentration parameters in the water column
Dissolved oxygen parameters in the water column
Nitrite concentration parameters in the water column
1  Instrument mooring
7  Multicorer
50  Sample taken from ship's non-toxic supplySalinity of the water column