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RRS Discovery D306
Cruise summary report
Cruise Info. | |
Ship name (ship code) | RRS Discovery (74E3) |
Cruise identifier | D306 |
Cruise period | 2006-06-23 — 2006-07-09 |
Status | Completed |
Port of departure | Falmouth, United Kingdom |
Port of return | Cork, Ireland |
Purpose | Research |
Objectives | The aim of this cruise was to develop a better understanding of carbon cycling in the pelagic waters of the Porcupine Abyssal Plain (PAP). There were three objectives:
1) Turnaround moorings at the PAP Observatory; 2) Conduct a 1-D time series on the central station of a wide range of biogeochmical processes and to back this up with a mesoscale survey of key variables; 3) To trial the use of Autosub for mesoscale surveys in conjuction with the ship. All objectives were met, although the tops of the moorings were found to be missing probably due to fishing activity and the Autosub trials were incomplete due to vehicle failure. A full mesoscale survey was carried out using the ship and an eleven day time series at the central station was achieved. Friday 23 June [JD174] Scientific party met at 13:00 to agree work plans. The Master gave welcome & safety talk at 15:00. We sailed at 18:00 after a series of delays. The Chief Officer was discharged off sick and a replacement was travelling from Lincolnshire. On reaching Plymouth, the railway shut due to a suicide on the track. The replacement mate required taxi from Plymouth to Falmouth. One of the ship's cranes broken, compromising our ability to handling moorings. The ship's engineers worked flat out yesterday and today and managed to cannibalise parts from other cranes. On sailing we moved into the lee of Falmouth Bay to carry out ship's compass check and then deployed Autosub briefly to check its sensors were working. The sea-state was surprisingly benevolent considering how hard the wind had been blowing for previous 3 days. The skies were still very cloudy. Saturday 24 June [JD175] We made an easy passage with winds BF 3-4. The scientists were finding their sea-legs, with no major problems. An Emergency muster & life boat drill was run at 10:30. We had a discussion about Autosub mission and decide to work the central box at PAP for the first deployment. |
Chief scientist | Peter H Burkill (National Oceanography Centre, Southampton) |
Project | BICEP |
Coordinating body | GDD, NOCS |
Cruise report | (1.81 MB) |
Ocean/sea areas | |
General | North East Atlantic Ocean (limit 40W) |
Specific | North Atlantic Ocean |
Measurements | |
Physical oceanography | |
Surface measurements underway (T,S) | Quantity: activity duration in days = 17 Description: On-line TSG: conductivity, temperature, fluorescence |
CTD stations | Quantity: number of profiles = 50 Description: CTD varying in depth from 200-4000m. 23 of 50 at PAP site. C,T,D,fluor, oxygen and for some ISUS NO3 and FRRF plus 24 bottles at every station |
Current profiler (eg ADCP) | Quantity: activity duration in days = 17 Description: Ship mounted ADCP operated throughout cruise |
Other physical oceanographic measurements | Quantity: activity duration in days = 4 Description: Moving Vessel Profiler: towed for 4 days, 18 hours per day, punctuated by CTD casts |
Other physical oceanographic measurements | Quantity: number of stations = 18 Description: Measurements of turbulent dissipation using freefall profiler. Typically 6-10 proilfes to 200+m per station |
Other physical oceanographic measurements | Quantity: number of samples = 334 Description: Salinometry from CTD bottle samples and on-line non-toxic |
Other physical oceanographic measurements | Quantity: track kilometres = 532 Description: CTD measurements by Autosub on 4 missions |
Chemical oceanography | |
Oxygen | Quantity: number of profiles = 50 Description: Samples from CTD bottles |
Phosphate | Quantity: number of profiles = 50 Description: Samples from CTD bottles |
Nitrate | Quantity: number of profiles = 50 Description: Samples from CTD bottles |
Silicate | Quantity: number of profiles = 50 Description: Samples from CTD bottles |
Biology and fisheries | |
Primary productivity | Quantity: activity duration in days = 12 Description: Prim Prod from 13C and 14C plus nitrate uptake from 15N using incubations from dawn cast |
Phytoplankton pigs (eg chlorophyll, fluorescence) | Quantity: number of profiles = 41 Description: FRRF measurements of physiology both continuous and from discreete CTD bottle samples |
Phytoplankton pigs (eg chlorophyll, fluorescence) | Quantity: number of profiles = 40 Description: HPLC analysis from range of depths from CTD bottles. Samples also taken from 3 SAPS and 2 sediment traps |
Particulate organic matter (inc POC, PON) | Quantity: number of profiles = 22 Description: Molecular diversity of photosynthetic picoeukaryotes |
Particulate organic matter (inc POC, PON) | Quantity: number of profiles = 11 Description: Micro-organisms role in uptake of CO2 and amino acids using stable isotopes |
Particulate organic matter (inc POC, PON) | Quantity: number of profiles = 5 Description: Microbial activity from uptake of isotopically labelled precursors |
Particulate organic matter (inc POC, PON) | Quantity: activity duration in days = 4 Description: Flow cytometric analysis of pico and anaoplankton underway at 12min intervals |
Particulate organic matter (inc POC, PON) | Quantity: activity duration in days = 12 Description: POC, PON from 12 depths to 200m at dawn every day |
Particulate organic matter (inc POC, PON) | Quantity: number of profiles = 13 Description: Flow cytometric analysis of pico and anaoplankton |
Particulate organic matter (inc POC, PON) | Quantity: track kilometres = 532 Description: Flow cytometric analysis of pico and anaoplankton underway from Cytometer on Autosub |
Sediment traps | Quantity: number of deployments = 9 Description: Deployments of PELAGRA drifting sediment traps |
Sediment traps | Quantity: number of profiles = 7 Description: Carbon export from 234Th and 238U disequilibria using CTD bottle stations from between 8-10 depths to a max of 1000m |
Phytoplankton | Quantity: number of stations = 11 Description: WP2 200micron nets for zooplankton from between 1 and 5 haul depths |
Phytoplankton | Quantity: activity duration in days = 12 Description: Size-fractionated phytoplankton biomass from 12 depths to 200m at dawn every day |
Zooplankton | Quantity: number of profiles = 8 Description: Microzooplankton grazing |
Zooplankton | Quantity: number of stations = 11 Description: 20micron Apstein nets for phytoplankton from between 1 and 5 haul depths |
Meteorology | |
Routine standard measurements | Quantity: activity duration in days = 17 Description: Standard met measurements |
Moorings, landers, buoys | |
Biology and fisheries | |
Sediment traps | 48° 59' 8" N 16° 25' 39" W — Sediment traps deployed: 2 at 3000m; 1 at 4700m (100mab) |
Data held at BODC | |
Discrete samples | |
2 Instrument mooring | Sedimentation flux quantification in the water column |