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RRS Discovery DY084 (AMT27, DY085)

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS Discovery (74EQ)
Cruise identifierDY084 (AMT27, DY085)
Cruise period2017-09-23 — 2017-11-05
StatusCompleted
Port of departureSouthampton, United Kingdom
Port of returnStanley, Falkland Islands (Malvinas)
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 scientistAndrew Rees (Plymouth Marine Laboratory), Phyllis Lam (University of Southampton School of Ocean and Earth Science)
ProjectAtlantic Meridional Transect (AMT)
Coordinating bodyNatural Environment Research Council (NERC)
Cruise reportRRS Discovery DY084 (AMT27, DY085) cruise report dy084-85.pdf (6.34 MB) 
Ocean/sea areas 
GeneralNorth Atlantic Ocean
South Atlantic Ocean
Track chartsRRS Discovery DY084 (AMT27, DY085) cruise track — dy084trk.pdf (0.13 MB) 
Measurements 
Physical oceanography 
Surface measurements underway (T,S)Quantity: activity duration in days = 41
Description: Continuous underway SST skin measurements from ISAR (Infrared SST Autonomous Radiometer).
Surface measurements underway (T,S)Quantity: activity duration in days = 41
Description: Magnetic Hull SST sensor at 4m depth ~ every 20 seconds.
CTD stationsQuantity: number of profiles = 79
Description: Bottle firing sensor data from CTD profiles, generated from SeaBird processing software.
CTD stationsQuantity: number of profiles = 79
Description: Processed and calibrated CTD profiles (salinity, temperature, oxygen concentration, fluorescence, transmittance, down-welling and upwelling PAR, backscatter) in ODV format.
CTD stationsQuantity: number of stations = 11
Description: Water sampling at CTD stations down to 1000 m
Transparency (eg transmissometer)Quantity: number of stations = 11
Description: Water sampling at CTD stations down to 1000 m
Optics (eg underwater light levels)Quantity: number of samples = 204
Description: Daily samples collected from 3 depths (Deep chlorophyll maximum, 20m and 5m) from the pre-dawn and noon CTD casts for the measurement of fluoresence and absorbance in seawater samples using a Cary Eclipse Luminescence spectrophotometer and a Cary 60 UV-Vis spectrophotometer respectively, in collaboration with Stuart Painter at NOCS.
Optics (eg underwater light levels)Quantity: number of samples = 46
Description: Samples collected from the non-toxic surface underway supply near continental shelf off UK, South Georgia and Falkland Islands. Samples analysed for fluoresence and absorbance in using a Cary Eclipse Luminescence spectrophotometer and Cary 60 UV-Vis spectrophotometer respectively, in collaboration with Stuart Painter at NOCS.
Optics (eg underwater light levels)Quantity: number of samples = 17
Description: Seawater samples collected every 2 days from the underway system and the CTD surface bottle for intercomparison of their Inherent Optical Properties (IOP)
Optics (eg underwater light levels)Quantity: activity duration in days = 39
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 = 4
Description: Two hand held WISP instruments were used to take above water radiometric measurements in each midday station. The measurements were taken at an azimuth angle of ?135 deg relative to the Sun.
Optics (eg underwater light levels)Quantity: activity duration in days = 41
Description: Above-water TriOS systems (TriOS Mess- und Datentechnik GmbH, Germany) is used for above water radiometric measurements. It composed of two RAMSES ARC hyperspectral radiometers measuring upwelling radiance Lu(?) and downwelling radiance Ld(?) in the same azimuthal plane, and one RAMSES ACC for downwelling irradiance Ed(0+,?). The spectral range is 350-950 nm at 3 nm step and 10 nm bandwidth. The nominal FOV of radiance sensors is 7 degrees. All three spectra are recorded simultaneously where the time interval between the scans was 10 s. The integration time is adjusted automatically in the range of 4ms - 4s based on the scene brightness.
Optics (eg underwater light levels)Quantity: number of stations = 5
Description: Above water radiometry was recorded in experimental underway mode during the ship departing from the station making a 360 degree arc.
Optics (eg underwater light levels)Quantity: number of stations = 5
Description: Water turbidity was measured from samples collected at surface (5 m depth) using a HACH 2100 turbidimeter, which measures side scattering at a NIR wavelength.
Optics (eg underwater light levels)Quantity: number of stations = 5
Description: Above water radiometry data were collected during 5 noon casts using a three sensor TRIOS RAMSES configuration installed on the met platform (1 irradiance, 1 water looking radiance, 1 sky looking radiance sensor). Data was collected at 0.1 Hz intervals for 20 minute periods. At some stations replicate 20 minute intervals were measured.
Instrumented wave measurementsQuantity: activity duration in days = 41
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))
Other physical oceanographic measurementsQuantity: number of samples = 100
Description: Urea analyses
Chemical oceanography 
OxygenQuantity: number of samples = 352
Description: Seawater samples collected daily at 4-5 depths from pre-dawn and noon casts for the measurement of dissolved oxygen by Winkler titration.
Carbon dioxideQuantity: number of samples = 158
Description: Seawater samples collected daily from the pre-dawn cast at 3-5 depths, for post-cruise analysis of Total Alkalinity and Dissolved Inorganic Carbon at PML.
Other dissolved gasesQuantity: number of samples = 314
Description: Samples collected from 4 depths (Surface, deep chlorophyll maximum, 300m and 500m) from pre-dawn and noon CTD casts for the measurement of dissolved nitrous oxide and methane in sea water using Gas Chromatograph SHIMADZU 2010 using FID and ECD detectors. Samples also collected from deep sea casts from varying depths as a part of an additional sampling programme.
Other dissolved gasesQuantity: number of samples = 109
Description: Between 4-6 samples collected daily and analysed for dissolved nitrous oxide and methane in sea water using Gas Chromatograph SHIMADZU 2010 using a FID and ECD detectors from the underway system
PhosphateQuantity: number of profiles = 76
Description: Discrete samples for macronutrients collected from each CTD cast (24 samples per cast, all Niskin bottles)
PhosphateQuantity: number of samples = 1680
Description: Nutrient analyses on CTD subsamples as well as incubated samples
NitrateQuantity: number of profiles = 76
Description: Discrete samples for macronutrients collected from each CTD cast (24 samples per cast, all Niskin bottles)
NitrateQuantity: number of samples = 1680
Description: Nutrient analyses on CTD subsamples as well as incubated samples
NitriteQuantity: number of profiles = 76
Description: Discrete samples for macronutrients collected from each CTD cast (24 samples per cast, all Niskin bottles)
NitriteQuantity: number of samples = 1680
Description: Nutrient analyses on CTD subsamples as well as incubated samples
Total - NQuantity: number of samples = 196
Description: Total dissolved nitrogen and organic carbon of incubated samples
AmmoniaQuantity: number of measurements = 1680
Description: Ammonium concentration measurements for in situ as well as incubated subsamples
SilicateQuantity: number of profiles = 76
Description: Discrete samples for macronutrients collected from each CTD cast (24 samples per cast, all Niskin bottles)
AlkalinityQuantity: number of samples = 158
Description: Seawater samples collected daily from the pre-dawn cast at 3-5 depths, for post-cruise analysis of Total Alkalinity and Dissolved Inorganic Carbon at PML.
IsotopesQuantity: number of samples = 15
Description: Seawater samples collected at 15 stations at 5 depths for oxygen (18O) and carbon (13C) stable isotope analyses
IsotopesQuantity: number of samples = 1008
Description: Nitrogen stable isotopic analyses of ammonium, nitrite/nitrate and dissolved organic nitrogen
IsotopesQuantity: number of samples = 396
Description: Nitrogen and carbon stable isotope analyses for particulate organic carbon and nitrogen samples before and after incubations with 15N-labeled substrates
Other chemical oceanographic measurementsQuantity: number of samples = 196
Description: Total dissolved nitrogen and organic carbon of incubated samples
Other chemical oceanographic measurementsQuantity: number of samples = 44
Description: Metaproteomics analyses
Other chemical oceanographic measurementsQuantity: number of samples = 248
Description: Filtration of surface seawater samples from solar noon CTD Niskin bottles for the quantification of N-osmolytes in collaboration with Rachael Beale and Ruth Airs at PML
Biology and fisheries 
Primary productivityQuantity: number of stations = 38
Description: Incubations for nitrogen and carbon fixation rates. Ambient 15N/13C natural abundance
Primary productivityQuantity: number of samples = 30
Description: Simulated in situ 14C integrated water column primary production
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of samples = 46
Description: Samples collected from the non-toxic surface underway supply near continental shelf off UK, South Georgia and Falkland Islands. Samples analysed for fluoresence and absorbance in using a Cary Eclipse Luminescence spectrophotometer and Cary 60 UV-Vis spectrophotometer respectively, in collaboration with Stuart Painter at NOCS.
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of samples = 36
Description: Daily samples collected from the CTD surface and Chl-a max bottles from noon casts for post-cruise analysis of high performance liquid chromatography (HPLC) phytoplankton pigments at PML.
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of samples = 163
Description: Samples collected from the non-toxic surface underway supply for post-cruise analysis of high performance liquid chromatography (HPLC) phytoplankton pigments at PML.
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of samples = 204
Description: Daily samples collected from 3 depths (Deep chlorophyll maximum, 20m and 5m) from the pre-dawn and noon CTD casts for the measurement of fluoresence and absorbance in seawater samples using a Cary Eclipse Luminescence spectrophotometer and a Cary 60 UV-Vis spectrophotometer respectively, in collaboration with Stuart Painter at NOCS.
Particulate organic matter (inc POC, PON)Quantity: number of samples = 44
Description: deployment of standalone pumps (SAP)
Dissolved organic matter (inc DOC)Quantity: number of samples = 196
Description: Total dissolved nitrogen and organic carbon of incubated samples
Dissolved organic matter (inc DOC)Quantity: number of samples = 15
Description: Microbial uptake of leucine, methionine, phosphate, bicarbonate in the surface mixed layers.
Dissolved organic matter (inc DOC)Quantity: number of samples = 67
Description: Daily samples collected from the CTD surface bottle from pre-dawn and noon casts for post-cruise analysis of dissolved organic carbon (DOC) at PML.
Dissolved organic matter (inc DOC)Quantity: number of samples = 46
Description: Samples collected from the non-toxic surface underway supply when around continental shelf for post-cruise analysis of dissolved organic carbon (DOC) at PML.
Dissolved organic matter (inc DOC)Quantity: number of samples = 5
Description: Microbial uptake of cobalt in twilight waters.
Biochemical measurements (eg lipids, amino acids)Quantity: number of samples = 44
Description: Metaproteomics analyses
Biochemical measurements (eg lipids, amino acids)Quantity: number of samples = 96
Description: RNA samples
PhytoplanktonQuantity: number of samples = 65
Description: 11 L Samples collected from solar noon CTD Niskin bottles at the deep chlorophyll maximum and 20 m depth and concentrated to 100-150 mL for analysis of microplankton community composition and abundance using FlowCAM in collaboration with Elaine Fileman at PML
PhytoplanktonQuantity: number of hauls = 29
Description: Daily predawn WP2 bongo (200 µm) vertical haul from 200 m to surface for mesoplankton community composition and abundance by microscopy/FlowCAM in collaboration with Elaine Fileman at PML
PhytoplanktonQuantity: number of profiles = 67
Description: Quantification of pico- and nanophytoplankton abundance from all depths between the surface and 200m from CTD casts by flow cytometry
ZooplanktonQuantity: number of hauls = 33
Description: A quantitative split (50%) of one of each Bongo nets was size fractionated and preserved in RNAlater for metabarcoding analyses
ZooplanktonQuantity: number of hauls = 29
Description: Daily predawn WP2 bongo (200 µm) vertical haul from 200 m to surface for mesoplankton community composition and abundance by microscopy/FlowCAM in collaboration with Elaine Fileman at PML
ZooplanktonQuantity: number of samples = 65
Description: 11 L Samples collected from solar noon CTD Niskin bottles at the deep chlorophyll maximum and 20 m depth and concentrated to 100-150 mL for analysis of microplankton community composition and abundance using FlowCAM in collaboration with Elaine Fileman at PML
ZooplanktonQuantity: number of hauls = 73
Description: >10,000 animals from >50 species were individually sorted and preserved from a total of 73 zooplankton tows
ZooplanktonQuantity: number of experiments = 41
Description: 17 ocean acidification experiments and 24 growth rate experiments were conducted on holoplanktonic gastropods (heteropods and pteropods)
ZooplanktonQuantity: number of samples = 11
Description: Seawater samples collected at 11 CTD casts for eDNA analyses
Pelagic bacteria/micro-organismsQuantity: number of profiles = 67
Description: Quantification of heterotrophic bacteria abundance from all depths between the surface and 200m from CTD casts by flow cytometry
Pelagic bacteria/micro-organismsQuantity: number of samples = 96
Description: RNA samples
Pelagic bacteria/micro-organismsQuantity: number of samples = 132
Description: 10 litres of seawater filtered onto 0.2µm sterivex filter. Filters will be archived for future DNA/RNA retrieval
Pelagic bacteria/micro-organismsQuantity: number of samples = 15
Description: Morphology and composition of microbes dominant in the surface mixed layer.
Pelagic bacteria/micro-organismsQuantity: number of samples = 44
Description: Metaproteomics analyses
Other biological/fisheries measurementQuantity: number of samples = 15
Description: Microbial uptake of leucine, methionine, phosphate, bicarbonate in the surface mixed layers.
Other biological/fisheries measurementQuantity: number of samples = 5
Description: Microbial uptake of cobalt in twilight waters.
Other biological/fisheries measurementQuantity: number of samples = 15
Description: Morphology and composition of microbes dominant in the surface mixed layer.
Meteorology 
Upper air observationsQuantity: number of measurements = 23
Description: Sky Infrared Brightness temperature measurements (9.5 to 11 um), full sky coverage. All sky camera 1 s time lapse during Sky BT measurements.
Routine standard measurementsQuantity: number of deployments = 38
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 = 41
Description: Underway continuous 3-axis wind speed and direction. Humidity and temperature sensors.
Other meteorological measurementsQuantity: activity duration in days = 41
Description: Above-water SATLANTIC system for above water radiometric measurements.
Other meteorological measurementsQuantity: number of profiles = 68
Description: Optical backscattering measurements, SBE CTD, Secchi Depth and WETLAbs AC9 to determine the particulate absorption and attenuation coefficients over the upper 250 m were collected on an optics profiler.
Other meteorological measurementsQuantity: activity duration in days = 17
Description: Fish eye images of the sky hemisphere
Moorings, landers, buoys 
Biology and fisheries 
Sediment traps18° 32' 42" S  25° 5' 52" W — Sediment trap and current meter mooring recovery.
Sediment traps18° 32' 42" S  25° 4' 47" W — Sediment trap and current meter mooring deployment.
Data held at BODC Get data
Discrete samples 
38  1 metre diameter zooplankton ring net
79  CTD frame plus rosette sampler
2  Instrument mooring
26  Metocean Argos Drifting Buoy
68  Optical instruments
2  RMT multiple zooplankton net tow
38  Radiosonde
143  Sample taken from ship's non-toxic supply
11  Stand-alone pumps
62  Twin WP-2 net mounted on a frame