RRS Discovery DY090
Cruise summary report
| Cruise Info. | |||||||||
| Ship name (ship code) | RRS Discovery (74EQ) | ||||||||
| Cruise identifier | DY090 | ||||||||
| Cruise period | 2018-05-23 — 2018-06-28 | ||||||||
| Status | Completed | ||||||||
| Port of departure | Walvis Bay, Namibia | ||||||||
| Port of return | Cape Town, South Africa | ||||||||
| Purpose | Research | ||||||||
| Objectives | This was the second of two cruises (first was DY086) 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 hypotheses explaining what controls this depth: plankton community structure, temperature and oxygen concentrations. The data collected during the COMICS cruises will test two of these: oxygen and community structure with DY090 examining the role of oxygen concentration, in particular how temporal variability in mesopelagic oxygen minima affects the remineralisation depth of sinking organic carbon.
In order to evaluate this 4 long stations of about 6 days duration each were worked over a 4 week period between May and June in the oxygen minimum zone in the Benguela upwelling region off the Namibian coast. Three of the stations were undertaken as a time series to investigate the evolution of the remineralisation depth in an oxygen minimum zone (~ 18S, 11E). The other station was in a relatively high oxygen region and served as a baseline to compare against (~ 21.5S, 9.5E). At each station surface and mesopelagic biomass and 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. | ||||||||
| Chief scientist | Stephanie Henson (National Oceanography Centre, Southampton) | ||||||||
| Project | Controls over Ocean Mesopelagic Interior Carbon Storage: COMICS | ||||||||
| Coordinating body | Natural Environment Research Council (NERC) | ||||||||
| Cruise report |  (13.41 MB) | ||||||||
| Ocean/sea areas | |||||||||
| General | South East Atlantic Ocean (limit 20W) | ||||||||
| Specific | Benguela Upwelling | ||||||||
| Measurements | |||||||||
| Physical oceanography | |||||||||
| CTD stations | Quantity: number of profiles = 9 Description: Trace Metal CTD casts | ||||||||
| CTD stations | Quantity: activity duration in days = 120 Description: Gliders | ||||||||
| Transparency (eg transmissometer) | Quantity: number of deployments = 35 Description: Red Camera Frame | ||||||||
| Optics (eg underwater light levels) | Quantity: number of deployments = 35 Description: Red Camera Frame | ||||||||
| Chemical oceanography | |||||||||
| Oxygen | Quantity: number of profiles = 9 Description: Trace Metal CTD casts | ||||||||
| Other dissolved gases | Quantity: number of profiles = 9 Description: Trace Metal CTD casts | ||||||||
| Phosphate | Quantity: number of profiles = 9 Description: Trace Metal CTD casts | ||||||||
| Nitrate | Quantity: number of profiles = 9 Description: Trace Metal CTD casts | ||||||||
| Ammonia | Quantity: number of deployments = 167 Description: Marine Snow Catchers | ||||||||
| Silicate | Quantity: number of profiles = 29 Description: Stainless Steel CTD Casts | ||||||||
| Alkalinity | Quantity: number of profiles = 29 Description: Stainless Steel CTD Casts | ||||||||
| Other chemical oceanographic measurements | Quantity: number of profiles = 29 Description: Stainless Steel CTD Casts | ||||||||
| Contamination | |||||||||
| Suspended matter | Quantity: number of deployments = 8 Description: Stand Alone Pumping Systems | ||||||||
| Suspended matter | Quantity: number of deployments = 167 Description: Marine Snow Catchers | ||||||||
| Biology and fisheries | |||||||||
| Primary productivity | Quantity: number of profiles = 29 Description: Stainless Steel CTD Casts | ||||||||
| Phytoplankton pigs (eg chlorophyll, fluorescence) | Quantity: number of profiles = 29 Description: Stainless Steel CTD Casts | ||||||||
| Particulate organic matter (inc POC, PON) | Quantity: activity duration in days = 120 Description: Gliders | ||||||||
| Particulate organic matter (inc POC, PON) | Quantity: number of deployments = 167 Description: Marine Snow Catchers | ||||||||
| Particulate organic matter (inc POC, PON) | Quantity: number of profiles = 29 Description: Stainless Steel CTD Casts | ||||||||
| Dissolved organic matter (inc DOC) | Quantity: activity duration in days = 120 Description: Gliders | ||||||||
| Dissolved organic matter (inc DOC) | Quantity: number of profiles = 29 Description: Stainless Steel CTD Casts | ||||||||
| Zooplankton | Quantity: number of profiles = 29 Description: Stainless Steel CTD Casts | ||||||||
| Zooplankton | Quantity: number of hauls = 7 Description: Mango net | ||||||||
| Zooplankton | Quantity: number of hauls = 7 Description: Mammoth net | ||||||||
| Zooplankton | Quantity: number of hauls = 29 Description: BONGO Net | ||||||||
| Zooplankton | Quantity: number of hauls = 14 Description: MOCNESS Net | ||||||||
| Nekton | Quantity: number of hauls = 19 Description: RMT 25 NET | ||||||||
| Moorings, landers, buoys | |||||||||
| Physical oceanography | |||||||||
| CTD stations | 18° 0' 0" S 11° 0' 0" E — 1 Slocum glider was deployed in February from the RV Mirabilis and recovered during this cruise. | ||||||||
| Subsurface temperature and salinity measurements | 18° 0' 0" S 11° 0' 0" E — 7 Deployments of Drifting neutrally bouyant sediment traps | ||||||||
| Transparency (eg transmissometer) | 18° 0' 0" S 11° 0' 0" E — 1 Slocum glider was deployed in February from the RV Mirabilis and recovered during this cruise. | ||||||||
| Surface drifters/drifting buoys | 18° 0' 0" S 11° 0' 0" E — 7 Deployments of Drifting array of in situ respirometers | ||||||||
| Neutrally buoyant floats | 18° 0' 0" S 11° 0' 0" E — 7 Deployments of Drifting neutrally bouyant sediment traps | ||||||||
| Chemical oceanography | |||||||||
| Oxygen | 18° 0' 0" S 11° 0' 0" E — 1 Slocum glider was deployed in February from the RV Mirabilis and recovered during this cruise. | ||||||||
| Oxygen | 18° 0' 0" S 11° 0' 0" E — 7 Deployments of Drifting array of in situ respirometers | ||||||||
| Biology and fisheries | |||||||||
| Phytoplankton pigs (eg chlorophyll, fluorescence) | 18° 0' 0" S 11° 0' 0" E — 1 Slocum glider was deployed in February from the RV Mirabilis and recovered during this cruise. | ||||||||
| Particulate organic matter (inc POC, PON) | 18° 0' 0" S 11° 0' 0" E — 7 Deployments of Drifting neutrally bouyant sediment traps | ||||||||
| Particulate organic matter (inc POC, PON) | 18° 0' 0" S 11° 0' 0" E — 7 Deployments of Drifting array of in situ respirometers | ||||||||
| Particulate organic matter (inc POC, PON) | 18° 0' 0" S 11° 0' 0" E — 1 Slocum glider was deployed in February from the RV Mirabilis and recovered during this cruise. | ||||||||
| Biochemical measurements (eg lipids, amino acids) | 18° 0' 0" S 11° 0' 0" E — 7 Deployments of Drifting neutrally bouyant sediment traps | ||||||||
| Sediment traps | 18° 0' 0" S 11° 0' 0" E — 7 Deployments of Drifting neutrally bouyant sediment traps | ||||||||
| Sediment traps | 18° 0' 0" S 11° 0' 0" E — 7 Deployments of Drifting array of in situ respirometers | ||||||||
| Data held at BODC | Get data | ||||||||
| Series/Profiles | |||||||||
| 1 Acoustic doppler current profiler | Reference numbers Horizontal spatial co-ordinates Date and time Vertical spatial coordinates Horizontal platform movement Horizontal velocity of the water column (currents) Reference numbers Horizontal spatial co-ordinates Date and time Vertical spatial coordinates Horizontal platform movement Horizontal velocity of the water column (currents)
| ||||||||
| 1 Meteorological data logger | Visible waveband radiance and irradiance measurements in the atmosphere Horizontal spatial co-ordinates Air pressure Date and time Air temperature Wind strength and direction Raw light meter output Solar Radiation Atmospheric humidity Visible waveband radiance and irradiance measurements in the atmosphere Horizontal spatial co-ordinates Air pressure Date and time Air temperature Wind strength and direction Raw light meter output Solar Radiation Atmospheric humidity
| ||||||||
| 1 Multiple instrument types | Horizontal spatial co-ordinates Transmittance and attenuance of the water column Date and time Salinity of the water column Temperature of the water column Metadata parameters Raw suspended particulate material concentration sensor output Electrical conductivity of the water column Raw fluorometer output Chlorophyll pigment concentrations in water bodies Horizontal spatial co-ordinates Transmittance and attenuance of the water column Date and time Salinity of the water column Temperature of the water column Metadata parameters Raw suspended particulate material concentration sensor output Electrical conductivity of the water column Raw fluorometer output Chlorophyll pigment concentrations in water bodies
| ||||||||
| 1 Single-beam echosounder | Horizontal spatial co-ordinates Date and time Platform or instrument orientation Horizontal platform movement Bathymetry and Elevation Horizontal spatial co-ordinates Date and time Platform or instrument orientation Horizontal platform movement Bathymetry and Elevation
| ||||||||
| Discrete samples | |||||||||
| 29 CTD frame plus rosette sampler | |||||||||
| 41 Drifting rig with sediment traps | |||||||||
| 169 Marine snow catcher | |||||||||
| 35 Optical instruments | |||||||||
| 19 RMT multiple zooplankton net tow | |||||||||
| 8 Stand-alone pumps | |||||||||
| 29 Twin WP-2 net mounted on a frame | |||||||||
| 74 Unspecified zooplankton net or nets | |||||||||
| 10 |
