Resources

RRS Discovery DY110 (AMT29)

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS Discovery (74EQ)
Cruise identifierDY110 (AMT29)
Cruise period2019-10-13 — 2019-11-25
StatusCompleted
Port of departureSouthampton, United Kingdom
Port of returnPunta Arenas, Chile
PurposeResearch
ObjectivesThe overall aim of the Atlantic Meridional Transect programme is: to quantify key biogeochemical and ecosystem processes and their inherent variability over extended time and spatial scales in the Atlantic Ocean. This is achieved by executing an annually repeated meridional transect through contrasting oceanic provinces, ranging from oligotrophic deserts, to highly productive shelf seas.

The specific objectives of AMT are:
- To quantify the nature and causes of ecological and biogeochemical variability in planktonic ecosystems;
- To quantify the effects of this variability on nutrient cycling, on biogenic export and on air-sea exchange of climate active gases;
- To construct multi-decadal, multidisciplinary ocean time-series which are integrated within a wider "Pole-to-pole" observatory concept;
- To provide essential sea-truth validation for current and next generation satellite missions;
- To provide essential data for global ecosystem model development and validation;
- To provide a valuable, highly sought after and unique training arena for the next generation of UK and International oceanographers.
Chief scientistGiorgio Dall'Olmo (Plymouth Marine Laboratory)
ProjectAtlantic Meridional Transect (AMT)
Coordinating bodyNatural Environment Research Council (NERC)
Ocean/sea areas 
GeneralNorth Atlantic Ocean
South Atlantic Ocean
Measurements 
Physical oceanography 
Surface measurements underway (T,S)Quantity: activity duration in days = 43
Description: Continuous measurements of underway pCO2 and pCO2 transfer resistance (10 min).
Surface measurements underway (T,S)Quantity: activity duration in days = 43
Description: Continuous measurements of ozone uptake to underway water (10 min).
Surface measurements underway (T,S)Quantity: number of measurements = 27
Description: Filtered underway water for iodide/iodate analysis, around noon (daily).
Surface measurements underway (T,S)Quantity: activity duration in days = 43
Description: Continuous underway SST skin measurements from ISAR (Infrared SST Autonomous Radiometer).
Surface measurements underway (T,S)Quantity: activity duration in days = 43
Description: Magnetic Hull SST sensor at 4m depth ~ every 20 seconds.
CTD stationsQuantity: number of profiles = 55
Description: Processing and calibration of CTD profiles (salinity, temperature, oxygen concentration, fluorescence, transmittance, attenuation, down-welling and upwelling PAR, and backscattering) generated from SeaBird processing software in ODV format.
Optics (eg underwater light levels)Quantity: number of profiles = 24
Description: Optical backscattering measurements, Hobilab Hydroscat-P6 SBE CTD, Secchi Depth and WETLAbs AC9 to determine the particulate absorption and attenuation coefficients over the upper 500 m were collected on an optics profiler.
Optics (eg underwater light levels)Quantity: activity duration in days = 38
Description: Optical underway system (WETLabs BB3, SBE CTD, WETLAbs ACS and Satlantic C-Star transmissometer) to collect continuous measurements of particulate absorption and attenuation coefficients and backscattering at the surface
Optics (eg underwater light levels)Quantity: activity duration in days = 40
Description: Above-water SATLANTIC system for above water radiometric measurements.
Instrumented wave measurementsQuantity: activity duration in days = 43
Description: Underway (approx. every 20 mins) Wave radar (Cband) measurements and camera footage with 40-80 images every 20 minutes.(alternative PI contact is Louis Marie (IFREMER))
Chemical oceanography 
OxygenQuantity: number of profiles = 55
Description: Determination of dissolved oxygen concentrations by automated Winkler titration from 4-15 depths at each pre-dawn and noon CTD cast. Data used to calibrate the oxygen sensor on the CTD rosette.
Carbon dioxideQuantity: activity duration in days = 43
Description: Continuous measurements of underway pCO2 and pCO2 transfer resistance (10 min).
Other dissolved gasesQuantity: number of samples = 44
Description: Collection of seawater samples from the noon CTD stations for post-cruise analysis of Dissolved Inorganic Carbon
PhosphateQuantity: number of profiles = 55
Description: Collection of samples from 4-15 depths at each pre-dawn and noon CTD cast. ~40mL seawater from each depth collected and stored at -20°c, to be analysed for micro-molar nutrient concentrations (nitrate, nitrite, phosphate and silicate) on return to Plymouth Marine Laboratory.
NitrateQuantity: number of profiles = 55
Description: Collection of samples from 4-15 depths at each pre-dawn and noon CTD cast. ~40mL seawater from each depth collected and stored at -20°c, to be analysed for micro-molar nutrient concentrations (nitrate, nitrite, phosphate and silicate) on return to Plymouth Marine Laboratory.
NitriteQuantity: number of profiles = 55
Description: Collection of samples from 4-15 depths at each pre-dawn and noon CTD cast. ~40mL seawater from each depth collected and stored at -20°c, to be analysed for micro-molar nutrient concentrations (nitrate, nitrite, phosphate and silicate) on return to Plymouth Marine Laboratory.
SilicateQuantity: number of profiles = 55
Description: Collection of samples from 4-15 depths at each pre-dawn and noon CTD cast. ~40mL seawater from each depth collected and stored at -20°c, to be analysed for micro-molar nutrient concentrations (nitrate, nitrite, phosphate and silicate) on return to Plymouth Marine Laboratory.
pHQuantity: number of profiles = 55
Description: pH samples collected from 15 Niskin bottle depths each pre-dawn and noon CTD. Samples
Trace elementsQuantity: number of samples = 115
Description: Samples for analysis of [Cr(tot)] & [Cr(III)] & d53Cr(tot). Collected from 8-10 depths at 12 stations.
Trace elementsQuantity: number of profiles = 40
Description: Collection of seawater samples at 8-18 depths from the pre-dawn and afternoon CTD stations for post-cruise analysis of Rare Earth Elements at Imperial College London
Trace elementsQuantity: number of samples = 18
Description: Samples for analysis of d53Cr(III). Collected from 6 depths at 3 stations.
IsotopesQuantity: number of samples = 18
Description: Samples for analysis of d53Cr(III). Collected from 6 depths at 3 stations.
IsotopesQuantity: number of samples = 115
Description: Samples for analysis of [Cr(tot)] & [Cr(III)] & d53Cr(tot). Collected from 8-10 depths at 12 stations.
Other chemical oceanographic measurementsQuantity: number of measurements = 27
Description: Filtered underway water for iodide/iodate analysis, around noon (daily).
Other chemical oceanographic measurementsQuantity: activity duration in days = 43
Description: Continuous measurements of ozone uptake to underway water (10 min).
Contamination 
Other dissolved substancesQuantity: number of profiles = 29
Description: Collection of seawater samples at 7 depths from the surface to 2000 m from noon CTD casts for post-cruise analysis of per- and polyfluoroalkyl substances (PFAS) at Stockholm university.
Other dissolved substancesQuantity: number of samples = 19
Description: Collection of sea spray aerosol (SSA) sample generated using the underway surface seawater supply for post-cruise targeted and non-targeted analysis of PFAS and other organic substances. Each experiment lasts 30 hours.
Biology and fisheries 
Primary productivityQuantity: number of samples = 53
Description: Incubations for carbon fixation rates using 14C for 2 depth: surface and DCM each noon CTD (27), 2 pre-dawn and 3 underways
Primary productivityQuantity: number of profiles = 29
Description: Collection of seawater from 4 - 6 depths at pre-dawn CTD's to determine Net Community Production, Dark Community Respiration and Gross Primary Production vertical profiles through in vitro changes in O2 after 24 hour incubations
Primary productivityQuantity: number of profiles = 29
Description: Primary production, size fractionated and total from 6 depths in the water column based on % light.
Primary productivityQuantity: number of samples = 219
Description: Samples for size fractionated phytoplankton absorption coefficients post-cruise analysis. Surface and DCM each pre-dawn and noon CTD
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of samples = 365
Description: Samples for High-Performance Liquid Chromatography (HPLC) post-cruise analysis. Surface and DCM each pre-dawn and noon CTD; underway 3xday
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of stations = 5
Description: Chla measurements for incubation on deck, x3 surface samples
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of experiments = 240
Description: Active fluorescence with CT-FastOcean on samples from temp & nutrient manipulation experiments
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of stations = 70
Description: Active fluorescence with CT-FastOcean at two depths (surface and DCM) and 3 size fractions (all, >10um, >2um)
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: activity duration in days = 43
Description: Continuous (every 30 min) active chlorophyll a fluorescence with CT-LabSTAF
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of samples = 280
Description: Fluorometric analysis of size fractionated Chl-a on board. Surface and DCM each pre-dawn and noon CTD
Biochemical measurements (eg lipids, amino acids)Quantity: number of stations = 35
Description: Samples for measuring TEPs and Viscosity, 0.4L x 6 depths
Biochemical measurements (eg lipids, amino acids)Quantity: number of stations = 35
Description: Samples for measuring Single-cell elemental composition, 9L from surface and DCM
PhytoplanktonQuantity: number of profiles = 55
Description: Phytoplankton samples from 5 depths between surface , DCM+, DCM, DCM- and 1 deeper each pre-dawn and noon CTD
PhytoplanktonQuantity: number of profiles = 55
Description: Quantification of pico- and nanophytoplankton abundance from all depths between the surface and 200m from CTD casts by flow cytometry
PhytoplanktonQuantity: number of samples = 55
Description: Collection of DNA samples from the surface at each pre-dawn and noon CTD cast. 1 litre of seawater filtered onto a 0.2µm Sterivex filter. Filters preserved with RNA Later solution and stored at -80°c to be analysed for DNA at a later date by the University of Southern California (USC).
PhytoplanktonQuantity: number of samples = 107
Description: Collection of DNA samples from the surface and DCM at each pre-dawn and noon CTD cast. ~5 litres of seawater from each depth filtered onto 0.2µm Sterivex filters. Filters preserved with RNA Later solution and stored at -80°c to be analysed for DNA on return to Plymouth Marine Laboratory.
PhytoplanktonQuantity: number of stations = 5
Description: Phytoplankton abundance for incubation on deck, x3 surface samples
PhytoplanktonQuantity: number of hauls = 21
Description: Daily predawn WP2 bongo (200 µm) vertical haul from 200 m to surface for mesoplankton community composition and abundance by microscopy/FlowCAM
PhytoplanktonQuantity: number of stations = 35
Description: Phytoplankton samples for measuring abundance with Flow Cam and Cytosense, 30ml samples x3 depths
PhytoplanktonQuantity: number of profiles = 55
Description: Abundance and of phytoplankton species Lugol's samples collected from surface and DCM each pre-dawn and noon CTD.
PhytoplanktonQuantity: number of samples = 24
Description: Determination of phytoplankton and bacteria median cell sizes from either mixed layer or deep chlorophyll maximum CTD water bottle samples by size fractionation filtration and flow cytometry.
ZooplanktonQuantity: number of samples = 55
Description: Collection of DNA samples from the surface at each pre-dawn and noon CTD cast. 1 litre of seawater filtered onto a 0.2µm Sterivex filter. Filters preserved with RNA Later solution and stored at -80°c to be analysed for DNA at a later date by the University of Southern California (USC).
ZooplanktonQuantity: number of samples = 107
Description: Collection of DNA samples from the surface and DCM at each pre-dawn and noon CTD cast. ~5 litres of seawater from each depth filtered onto 0.2µm Sterivex filters. Filters preserved with RNA Later solution and stored at -80°c to be analysed for DNA on return to Plymouth Marine Laboratory.
ZooplanktonQuantity: number of hauls = 21
Description: Daily predawn WP2 bongo (200 µm) vertical haul from 200 m to surface for mesoplankton community composition and abundance by microscopy/FlowCAM
Pelagic bacteria/micro-organismsQuantity: number of samples = 55
Description: Collection of samples from the surface at each pre-dawn and noon CTD cast, to be analysed for viruses. 1 litre of seawater filtered onto a 0.02µm Anotop filter and stored at -80°c for analysis at a later date by the University of Southern California (USC).
Pelagic bacteria/micro-organismsQuantity: number of profiles = 27
Description: Collection of seawater samples at 9-10 depths from the surface to 1000 m from solar noon CTD casts for molecular identification and flow cytometric enumeration of Archaea. Samples fixed with glutaraldehyde, flash-frozen with liquid nitrogen and stored at -80 deg. C for analysis ashore.
Pelagic bacteria/micro-organismsQuantity: number of profiles = 55
Description: Quantification of heterotrophic bacteria abundance from all depths from CTD casts by flow cytometry
Pelagic bacteria/micro-organismsQuantity: number of samples = 24
Description: Determination of phytoplankton and bacteria median cell sizes from either mixed layer or deep chlorophyll maximum CTD water bottle samples by size fractionation filtration and flow cytometry.
Other biological/fisheries measurementQuantity: number of samples = 56
Description: Particle size distribution using a Coulter Counter for samples collected from noon CTD casts
Meteorology 
Upper air observationsQuantity: number of measurements = 21
Description: Sky Infrared Brightness temperature measurements, full sky coverage sampled every 2s.
Routine standard measurementsQuantity: number of deployments = 28
Description: Radiosonde deployments measuring air temperature, humidity, wind speed and wind direction (alternative PI contacts are Gavin Tilstone (PML) or Steve Cowell (BAS))
Routine standard measurementsQuantity: activity duration in days = 43
Description: Underway continuous Humidity and temperature sensors.
Atmospheric chemistryQuantity: activity duration in days = 38
Description: Aerosol samples for metal trace, nutrients analysis and particle size distribution, 24-48 h
Atmospheric chemistryQuantity: activity duration in days = 43
Description: Continuous measurements of atmospheric ozone concentration (10 s).
Other meteorological measurementsQuantity: activity duration in days = 19
Description: Aerosol Optical Depth measurement with Microtops II sunphotometer (5 channels: 380, 440, 675, 870 and 936 nm) for MAN-NASA data available at https://aeronet.gsfc.nasa.gov/new_web/cruises_new/Discovery_19_0.html
Moorings, landers, buoys 
Biology and fisheries 
Sediment traps18° 32' 35" S  25° 38' 35" W — Sediment trap and current meter mooring deployment (SAG Mooring)
Sediment traps18° 30' 2" S  25° 6' 34" W — Sediment trap and current meter mooring recovery (SAG Mooring)
Data held at BODC 
Discrete samples 
55  CTD frame plus rosette sampler
11  Metocean Argos Drifting Buoy
23  Optical instruments
28  Radiosonde
21  Twin WP-2 net mounted on a frame