RRS Discovery D211
Cruise summary report
| Cruise Info. | |
| Ship name (ship code) | RRS Discovery (74E3) |
| Cruise identifier | D211 |
| Cruise period | 1994-10-09 — 1994-11-11 |
| Status | Completed |
| Port of departure | Muscat, Oman |
| Port of return | Muscat, Oman |
| Purpose | Research |
| Objectives | The cruise formed part of a suite of four cruises (209-212) on RRS Discovery during her 1994 Indian Ocean Campaign. The overall objectives of RRS Discovery cruise 211 were the following:
1. To test the hypothesis that the Oxygen Minimum Zone (OMZ) has a profound effect on community composition, abundance, diversity, size structure, reproductive mode and lifestyle of benthic biota by a comprehensive sampling strategy across areas where the OMZ impinges on the bottom. 2. To see what role the OMZ, and other related physical gradients, play in determining depth-related changes in the benthic community compared to data sets available from the northern Atlantic. 3. To test whether the upper and lower OMZ boundary is a zone of enhanced biological activity with respect to the benthos in the Arabian Sea. 4. To measure size-related biomass, particulate organic carbon fluxes and total benthic metabolism in the sediment at sites within and below the OMZ in order to examine the roles of different food-web components in the benthos, particularly in the context of carbon, nitrate and sulphate fluxes and the relative importance of aerobic and anaerobic metabolism in the sediment. 5. To investigate the benthic response in terms of biogenic reworking, bioturbation, redox conditions and burial rates along oxygen gradients through the OMZ and in response to seasonal carbon input in relation to benthic fluxes and activity, and to determine how organism interactions affect the recycling and/or burial of organic matter. |
| Chief scientist | John D Gage (Dunstaffnage Marine Laboratory) |
| Cruise report |  (7.74 MB) |
| Ocean/sea areas | |
| General | Arabian Sea |
| Specific | Arabian Sea, Continental margin of Southern Oman |
| Track charts |  |
| Measurements | |
| Physical oceanography | |
| CTD stations | Quantity: number of stations = 22 Description: CTDs, one station analysed for nutrients, chlorophyll, phyto/microzooplankton |
| Chemical oceanography | |
| Oxygen | Description: diss. oxygen (Winkler), salinity, sulphate, carbon, nitrogen |
| Oxygen | Quantity: number of cores = 2 Description: O2 above and below sediment/water interface |
| Carbon dioxide | Quantity: number of cores = 4 Description: organic geochemistry |
| Carbon dioxide | Quantity: number of cores = 4 Description: bacteria/organic geochemistry/worms |
| Total - N | Quantity: number of cores = 27 Description: organic geochemistry |
| Total - N | Quantity: number of cores = 4 Description: bacteria/organic geochemistry/worms |
| Total - N | Quantity: number of cores = 4 Description: organic geochemistry |
| pH | Quantity: number of cores = 17 Description: bioturbation estimates, redox conditions, sediment strength |
| Isotopes | Quantity: number of cores = 70 Description: isotope incubations for mass spectrometry (15N), GC (N20) analysis |
| Isotopes | Quantity: number of cores = 27 Description: organic geochemistry |
| Isotopes | Quantity: number of samples = 180 Description: sediments sectioned at 1cm intervals for Pb-210 analysis; 6 cores/station |
| Isotopes | Quantity: number of cores = 1 Description: Kasten corer, deep frozen for later C14 analysis |
| Other chemical oceanographic measurements | Quantity: number of cores = 27 Description: organic geochemistry |
| Other chemical oceanographic measurements | Quantity: number of cores = 17 Description: bioturbation estimates, redox conditions, sediment strength |
| Contamination | |
| Trace metals | Quantity: number of cores = 27 Description: organic geochemistry |
| Biology and fisheries | |
| Phytoplankton pigs (eg chlorophyll, fluorescence) | Quantity: number of samples = 180 Description: for HPLC analysis of pigments |
| Dissolved organic matter (inc DOC) | Quantity: number of cores = 4 Description: organic geochemistry |
| Dissolved organic matter (inc DOC) | Quantity: number of cores = 4 Description: bacteria/organic geochemistry/worms |
| Biochemical measurements (eg lipids, amino acids) | Quantity: number of cores = 9 Description: foram lipid biochemistry |
| Biochemical measurements (eg lipids, amino acids) | Quantity: number of cores = 27 Description: organic geochemistry |
| Zooplankton | Quantity: number of hauls = 2 Description: vertical net hauls in 200m |
| Benthic bacteria/micro-organisms | Quantity: number of cores = 4 Description: bacteria/organic geochemistry/worms |
| Benthic bacteria/micro-organisms | Quantity: number of cores = 10 Description: bacteria/geochemistry/nematodes |
| Benthic bacteria/micro-organisms | Quantity: number of cores = 4 Description: organic geochemistry |
| Zoobenthos | Quantity: number of cores = 4 Description: bacteria/organic geochemistry/worms |
| Zoobenthos | Quantity: number of hauls = 9 Description: Agassiz trawls, megabenthos |
| Zoobenthos | Quantity: number of deployments = 2 Description: Epibenthic sledges, megabenthos |
| Zoobenthos | Quantity: number of cores = 4 Description: organic geochemistry |
| Zoobenthos | Quantity: number of cores = 49 Description: USNEL box core samples |
| Zoobenthos | Quantity: number of deployments = 44 Description: Multiple corer;12 cores/deployment;meiofauna/foraminifera abundance |
| Zoobenthos | Quantity: number of hauls = 5 Description: Tjarno dredges for megabenthos |
| Molluscs | Quantity: number of hauls = 9 Description: Agassiz trawls, megabenthos |
| Molluscs | Quantity: number of deployments = 44 Description: Multiple corer;12 cores/deployment;meiofauna/foraminifera abundance |
| Molluscs | Quantity: number of hauls = 5 Description: Tjarno dredges for megabenthos |
| Molluscs | Quantity: number of deployments = 2 Description: Epibenthic sledges, megabenthos |
| Crustaceans | Quantity: number of hauls = 9 Description: Agassiz trawls, megabenthos |
| Crustaceans | Quantity: number of deployments = 2 Description: Epibenthic sledges, megabenthos |
| Crustaceans | Quantity: number of hauls = 5 Description: Tjarno dredges for megabenthos |
| Crustaceans | Quantity: number of deployments = 44 Description: Multiple corer;12 cores/deployment;meiofauna/foraminifera abundance |
| Other biological/fisheries measurement | Quantity: number of cores = 17 Description: bioturbation estimates, redox conditions, sediment strength |
| Other biological/fisheries measurement | Quantity: number of images = 100 Description: x-ray radiographs of sediment slabs for biogenic structure analysis |
| Geology and geophysics | |
| Bottom photography | Quantity: number of images = 40 Description: bottom photographs; 2-4 at each station |
| Bottom photography | Quantity: number of deployments = 5 Description: epibenthic camera sled, transects for megabenthos, densities, biomass |
| Other geological/geophysical measurements | Quantity: number of cores = 17 Description: bioturbation estimates, redox conditions, sediment strength |
| Moorings, landers, buoys | |
| Biology and fisheries | |
| Zoobenthos | 19° 49' 0" N 58° 23' 59" E — 3hr video benthic lander mechanism/sea bed activity |
| Pelagic fish | 19° 49' 0" N 58° 23' 59" E — 3hr video benthic lander mechanism/sea bed activity |
| Pelagic fish | 19° 22' 0" N 58° 10' 59" E — loss of lander and equipment |
| Geology and geophysics | |
| Bottom photography | 19° 49' 0" N 58° 23' 59" E — 3hr video benthic lander mechanism/sea bed activity |
| Data held at BODC | |
| Discrete samples | |
| 22 CTD frame plus rosette sampler | Transmittance and attenuance of the water column Salinity of the water column Temperature of the water column Dissolved oxygen parameters in the water column Visible waveband radiance and irradiance measurements in the water column Density of the water column Raw light meter output Raw fluorometer output |
