Cruise inventory

RRS Discovery D373

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS Discovery (74E3)
Cruise identifierD373
Cruise period2011-12-07 — 2012-01-28
StatusCompleted
Port of departureBalboa, Panama
Port of returnSalina Cruz, Mexico
PurposeResearch
ObjectivesWith this research cruise we aim to study N cycle in a non- yet characterized OMZ, the Eastern Tropical North Pacific (ETNP). The overall aim of this project is to link N cycling to bacterial gene diversity and expression across a gradient of OMZ intensity in the East Tropical North Pacific (ETNP). Firstly by characterization of the water column (e.g. N2O, CO2, CH4 profiles) and then experimental manipulations to test if the ratio of N2 to N2O production is 'fixed' or 'flexible', screening for N2 production coupled to 15N organic-N and a molecular analysis of the active communities involved in the metabolism of these gases. In order to determine the extent of variation and potential within the water column, we performed experiments at 6 different sites, outside, on the edge and within the core OMZ. Understanding this response will help to us to predict the conditions under which N2O accumulates and will further clarify the mechanisms of fine tuning of the nitrogen cycle in the global ocean.

In addition, we set up experiments for the measurement of anaerobic methane oxidation, methane oxidation rates and tracing of the oxidised carbon into end products of methane oxidation by 13C-labelling in seawater samples. This will offer insights into carbon cycling in this area of the ocean.
Chief scientistMark Trimmer (Queen Mary University of London School of Biological and Chemical Sciences)
Cruise reportRRS Discovery D373 cruise report d373.pdf — access key 'C' (1.48 MB) 
Ocean/sea areas 
GeneralNorth East Pacific Ocean (limit 180W)
SpecificEastern Tropical North Pacific
Track chartsRRS Discovery D373 cruise track — d373trk.pdf (0.08 MB) 
Measurements 
Physical oceanography 
Surface measurements underway (T,S)Quantity: number of track lines = 1
Description: Underway measurements from the non-toxic supply
CTD stationsQuantity: number of profiles = 460
Description: CTD profiles - NO2, NO3, PO4, NH4+ in water column, measured using Skalar
CTD stationsQuantity: number of profiles = 24
Description: Organic N stable isotopes addition in seawater samples and incubation on-board; transfer to the lab to measure N2 production by IRMS
CTD stationsQuantity: number of profiles = 21
Description: Addition of 13CH4 gas to water samples and incubation on board, transfer to the lab to measure 13CO2 production with IRMS
CTD stationsQuantity: number of profiles = 30
Description: Treatment with pre-mixed gases/15NO2- addition in seawater samples and incubation on-board; transfer to the lab to measure N2 and N2O production by IRMS
CTD stationsQuantity: number of profiles = 21
Description: Addition of saturated 13CH4 solution to water samples and incubation on board, transfer to the lab to filter samples and measure the assimilation of 13C to the biomass of bacteria with IRMS
CTD stationsQuantity: number of profiles = 460
Description: CTD vertical profiles of CO2, CH4, N2O in water column, measured using GC
CTD stationsQuantity: number of profiles = 237
Description: Discrete CTD water samples were taken for analysis on shore of natural abundance isotopes of NO3- and NO2-
CTD stationsQuantity: number of profiles = 460
Description: CTD profiles - vertical profiles of DON in water column, to be analysed in the lab using Skalar
CTD stationsQuantity: number of profiles = 21
Description: Addition of 12CH4 gas to water samples and incubation on board, measuring changes in concentrations of CH4 and CO2 with GC on board and finally on shore/in the lab
CTD stationsQuantity: number of profiles = 139
Description: Water samples from chosen depths were preserved and transferred to the lab for measurement of δ13C values of CH4
CTD stationsQuantity: number of profiles = 42
Description: Transect CTD casts for continuous oxygen measurements in between stations, 10 m-surface-150 m
CTD stationsQuantity: number of profiles = 345
Description: CTD profiles - vertical profiles of NH4+ in water column, measured using Turner fluorometer
CTD stationsQuantity: number of stations = 3
Description: Seawater samples sealed in serum bottles, transferred to the lab for measuring CH4 production with GC
CTD stationsQuantity: number of profiles = 10
Description: Addition of 13CH4 and 15NO2- to water samples, onboard incubation and transfer to the lab for IRMS analysis of CO2 and N2
CTD stationsQuantity: number of profiles = 30
Description: 15NO3- or 15NO2- stable isotope additions to seawater samples and incubation onboard, discrete samples returned for onshore analysis of NO3-, NO2- & NH4+ by IRMS to determine N cycling pathways
Chemical oceanography 
OxygenQuantity: number of profiles = 42
Description: Transect CTD casts for continuous oxygen measurements in between stations, 10 m-surface-150 m
OxygenQuantity: number of deployments = 1
Description: Scanfish deployed for continuous oxygen measurements. Unfortunately, scanfish was lost in the ocean.
Carbon dioxideQuantity: number of profiles = 21
Description: Addition of 12CH4 gas to water samples and incubation on board, measuring changes in concentrations of CH4 and CO2 with GC on board and finally on shore/in the lab
Carbon dioxideQuantity: number of profiles = 460
Description: CTD vertical profiles of CO2, CH4, N2O in water column, measured using GC
Carbon dioxideQuantity: number of profiles = 21
Description: Addition of 13CH4 gas to water samples and incubation on board, transfer to the lab to measure 13CO2 production with IRMS
Other dissolved gasesQuantity: number of profiles = 460
Description: CTD vertical profiles of CO2, CH4, N2O in water column, measured using GC
Other dissolved gasesQuantity: number of profiles = 21
Description: Addition of 12CH4 gas to water samples and incubation on board, measuring changes in concentrations of CH4 and CO2 with GC on board and finally on shore/in the lab
Other dissolved gasesQuantity: number of stations = 3
Description: Seawater samples sealed in serum bottles, transferred to the lab for measuring CH4 production with GC
PhosphateQuantity: number of profiles = 460
Description: CTD profiles - NO2, NO3, PO4, NH4+ in water column, measured using Skalar
NitrateQuantity: number of profiles = 460
Description: CTD profiles - NO2, NO3, PO4, NH4+ in water column, measured using Skalar
NitriteQuantity: number of profiles = 460
Description: CTD profiles - NO2, NO3, PO4, NH4+ in water column, measured using Skalar
Total - NQuantity: number of profiles = 460
Description: CTD profiles - vertical profiles of DON in water column, to be analysed in the lab using Skalar
AmmoniaQuantity: number of profiles = 345
Description: CTD profiles - vertical profiles of NH4+ in water column, measured using Turner fluorometer
AmmoniaQuantity: number of profiles = 460
Description: CTD profiles - NO2, NO3, PO4, NH4+ in water column, measured using Skalar
IsotopesQuantity: number of profiles = 6
Description: Seawater samples from CTD collected for incubations with labelled 13C compounds to carry out stable isotope probing (SIP) techniques onshore
IsotopesQuantity: number of profiles = 10
Description: Addition of 13CH4 and 15NO2- to water samples, onboard incubation and transfer to the lab for IRMS analysis of CO2 and N2
IsotopesQuantity: number of profiles = 24
Description: Organic N stable isotopes addition in seawater samples and incubation on-board; transfer to the lab to measure N2 production by IRMS
IsotopesQuantity: number of profiles = 30
Description: 15NO3- or 15NO2- stable isotope additions to seawater samples and incubation onboard, discrete samples returned for onshore analysis of NO3-, NO2- & NH4+ by IRMS to determine N cycling pathways
IsotopesQuantity: number of profiles = 21
Description: Addition of saturated 13CH4 solution to water samples and incubation on board, transfer to the lab to filter samples and measure the assimilation of 13C to the biomass of bacteria with IRMS
IsotopesQuantity: number of profiles = 30
Description: Treatment with pre-mixed gases/15NO2- addition in seawater samples and incubation on-board; transfer to the lab to measure N2 and N2O production by IRMS
IsotopesQuantity: number of profiles = 21
Description: Addition of 13CH4 gas to water samples and incubation on board, transfer to the lab to measure 13CO2 production with IRMS
IsotopesQuantity: number of profiles = 237
Description: Discrete CTD water samples were taken for analysis on shore of natural abundance isotopes of NO3- and NO2-
IsotopesQuantity: number of profiles = 139
Description: Water samples from chosen depths were preserved and transferred to the lab for measurement of δ13C values of CH4
Biology and fisheries 
PhytoplanktonQuantity: number of samples = 35
Description: SAPs deployment; filters transferred to the lab for bacterioplankton, phytoplankton and zooplankton analysis
ZooplanktonQuantity: number of samples = 35
Description: SAPs deployment; filters transferred to the lab for bacterioplankton, phytoplankton and zooplankton analysis
Pelagic bacteria/micro-organismsQuantity: number of profiles = 6
Description: Bacterial cells fixed from seawater samples for fluorescent in-situ hybridisation (FISH) and microscopy
Pelagic bacteria/micro-organismsQuantity: number of profiles = 6
Description: Seawater samples from CTD collected for incubations with labelled 13C compounds to carry out stable isotope probing (SIP) techniques onshore
Pelagic bacteria/micro-organismsQuantity: number of profiles = 31
Description: Seawater from CTD filtered for onshore DNA and RNA analysis to look for bacterial community composition and dynamics
Pelagic bacteria/micro-organismsQuantity: number of profiles = 21
Description: Addition of saturated 13CH4 solution to water samples and incubation on board, transfer to the lab to filter samples and measure the assimilation of 13C to the biomass of bacteria with IRMS
Pelagic bacteria/micro-organismsQuantity: number of samples = 35
Description: SAPs deployment; filters transferred to the lab for bacterioplankton, phytoplankton and zooplankton analysis
Meteorology 
Routine standard measurementsQuantity: number of track lines = 1
Description: Ship-mounted meteorological sensors