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RRS Discovery DY086 (COMICS)

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS Discovery (74EQ)
Cruise identifierDY086 (COMICS)
Cruise period2017-11-12 — 2017-12-19
StatusCompleted
Port of departureStanley, Falkland Islands (Malvinas)
Port of returnStanley, Falkland Islands (Malvinas)
PurposeResearch
ObjectivesThis is one of two cruises aimed at evaluating the controls over mesopelagic remineralisation depth. This is the depth to which material sinks when it leaves the surface ocean, a factor we know to be a critical control over climate. There are three serious hypotheses explaining what controls this depth; plankton community structure, temperature and oxygen concentrations. COMICS will test two of these; oxygen and community structure with this cruise exaimining the role of community structure; more precisely how the evolution of community structure over the course of the bloom affects sinking depth.

In order to evaluate this three long stations of about a week duration each were worked over a 1 mo period between mid Nov and mid Dec in the major plankton bloom which occurs NW of South Georgia. At each station surface community structure and a variety of metrics of downward particle flux were measured, together with estimates of the biomass and growth rates of the major taxonomic classes of organisms responsible for consuming sinking material. All operations were conducted in the vicinity of BAS station P3 (52 40 S, 40 06 W).
Chief scientistRichard Sanders (National Oceanography Centre, Southampton)
ProjectControls over Ocean Mesopelagic Carbon Storage (COMICS)
Cruise reportRRS Discovery DY086 (COMICS) cruise report dy086.pdf (57.86 MB) 
Ocean/sea areas 
GeneralSouth West Atlantic Ocean (limit 20W)
SpecificSouth Georgia
Track chartsRRS Discovery DY086 (COMICS) cruise track — dy086trk.pdf (0.17 MB) 
Measurements 
Physical oceanography 
Surface measurements underway (T,S)Quantity: activity duration in days = 40
Description: Underway Sampling
CTD stationsQuantity: number of profiles = 15
Description: Trace Metal CTD casts
CTD stationsQuantity: activity duration in days = 60
Description: Gliders
Transparency (eg transmissometer)Quantity: number of deployments = 30
Description: Red Camera Frame
Optics (eg underwater light levels)Quantity: number of deployments = 30
Description: Red Camera Frame
Current profiler (eg ADCP)Quantity: activity duration in days = 40
Description: Underway Sampling
Chemical oceanography 
OxygenQuantity: number of profiles = 15
Description: Trace Metal CTD casts
Other dissolved gasesQuantity: number of profiles = 15
Description: Trace Metal CTD casts
PhosphateQuantity: number of profiles = 15
Description: Trace Metal CTD casts
NitrateQuantity: number of profiles = 15
Description: Trace Metal CTD casts
AmmoniaQuantity: number of deployments = 100
Description: Marine Snow Catchers. Over 100 deployments
SilicateQuantity: number of profiles = 15
Description: Stainless Steel CTD Casts
AlkalinityQuantity: number of profiles = 15
Description: Stainless Steel CTD Casts
Other chemical oceanographic measurementsQuantity: number of profiles = 15
Description: Stainless Steel CTD Casts
Contamination 
Suspended matterQuantity: number of deployments = 15
Description: Stand Alone Pumping Systems
Suspended matterQuantity: number of deployments = 100
Description: Marine Snow Catchers. Over 100 deployments
Biology and fisheries 
Primary productivityQuantity: number of profiles = 15
Description: Stainless Steel CTD Casts
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of profiles = 15
Description: Stainless Steel CTD Casts
Particulate organic matter (inc POC, PON)Quantity: number of deployments = 100
Description: Marine Snow Catchers. Over 100 deployments
Particulate organic matter (inc POC, PON)Quantity: activity duration in days = 60
Description: Gliders
Particulate organic matter (inc POC, PON)Quantity: number of profiles = 15
Description: Stainless Steel CTD Casts
Dissolved organic matter (inc DOC)Quantity: activity duration in days = 60
Description: Gliders
Dissolved organic matter (inc DOC)Quantity: number of profiles = 15
Description: Stainless Steel CTD Casts
ZooplanktonQuantity: number of profiles = 15
Description: Stainless Steel CTD Casts
ZooplanktonQuantity: number of deployments = 25
Description: Bongo Net
ZooplanktonQuantity: number of deployments = 6
Description: MOCNESS Net
ZooplanktonQuantity: number of deployments = 6
Description: Mammoth Net
NektonQuantity: number of deployments = 8
Description: RMT 25 NET
Moorings, landers, buoys 
Physical oceanography 
CTD stations52° 42' 17" S  40° 6' 24" W — 2 Gliders were continuously patrolling the work area, with the deployment period starting approx one month before, ane ending about 1 mo after, the cruise dates.
CTD stations52° 42' 17" S  40° 6' 24" W — 6 Argo Floats
Subsurface temperature and salinity measurements52° 42' 0" S  40° 6' 24" W — 7 Deployments of Drifting neutrally bouyant sediment traps
Transparency (eg transmissometer)52° 42' 17" S  40° 6' 24" W — 2 Gliders were continuously patrolling the work area, with the deployment period starting approx one month before, ane ending about 1 mo after, the cruise dates.
Surface drifters/drifting buoys52° 41' 53" S  40° 10' 5" W — 3 Deployments of Drifting array of in situ respirometers
Neutrally buoyant floats52° 42' 17" S  40° 6' 24" W — 6 Argo Floats
Neutrally buoyant floats52° 42' 0" S  40° 6' 24" W — 7 Deployments of Drifting neutrally bouyant sediment traps
Chemical oceanography 
Oxygen52° 42' 17" S  40° 6' 24" W — 2 Gliders were continuously patrolling the work area, with the deployment period starting approx one month before, ane ending about 1 mo after, the cruise dates.
Oxygen52° 41' 53" S  40° 10' 5" W — 3 Deployments of Drifting array of in situ respirometers
Oxygen52° 42' 17" S  40° 6' 24" W — 6 Argo Floats
pH52° 42' 17" S  40° 6' 24" W — 6 Argo Floats
Biology and fisheries 
Phytoplankton pigs (eg chlorophyll, fluorescence)52° 42' 17" S  40° 6' 24" W — 2 Gliders were continuously patrolling the work area, with the deployment period starting approx one month before, ane ending about 1 mo after, the cruise dates.
Particulate organic matter (inc POC, PON)52° 42' 17" S  40° 6' 24" W — 2 Gliders were continuously patrolling the work area, with the deployment period starting approx one month before, ane ending about 1 mo after, the cruise dates.
Particulate organic matter (inc POC, PON)52° 41' 53" S  40° 10' 5" W — 3 Deployments of Drifting array of in situ respirometers
Particulate organic matter (inc POC, PON)52° 42' 0" S  40° 6' 24" W — 7 Deployments of Drifting neutrally bouyant sediment traps
Biochemical measurements (eg lipids, amino acids)52° 42' 0" S  40° 6' 24" W — 7 Deployments of Drifting neutrally bouyant sediment traps
Sediment traps52° 41' 53" S  40° 10' 5" W — 3 Deployments of Drifting array of in situ respirometers
Sediment traps52° 42' 0" S  40° 6' 24" W — 7 Deployments of Drifting neutrally bouyant sediment traps
Data held at BODC Get data
Discrete samples 
3  Autonomous Underwater Vehicle deployment
25  CTD frame plus rosette sampler
42  Drifting rig with sediment traps
126  Marine snow catcher
26  Optical instruments
7  RMT multiple zooplankton net tow
5  Stand-alone pumps
31  Twin WP-2 net mounted on a frame
15  Unspecified zooplankton net or nets
8