RRS James Cook JC066 (JC067)
Cruise summary report
| Cruise Info. | |
| Ship name (ship code) | RRS James Cook (740H) |
| Cruise identifier | JC066 (JC067) |
| Cruise period | 2011-11-07 — 2011-12-21 |
| Status | Completed |
| Port of departure | Cape Town, South Africa |
| Port of return | Port Elizabeth, South Africa |
| Purpose | Research |
| Objectives | Seamounts are centres of biological diversity and are ecological hotspots in the deep ocean but their inaccessibility poses major challenges for research. In consequence, there are conspicuous sampling gaps of which the equatorial regions and most of the Indian Ocean are the most extensive. The southwest Indian Ridge (SWIR) is a major geological feature which extends from the central Indian Ocean to join the Mid-Atlantic Ridge in the Southern Ocean. It is rich in seamounts and supports a productive deep-water fishery yet, in terms of biodiversity and ecosystem functioning, it is one of the least sampled regions of the global ocean. This study was undertaken to describe and analyse the diversity and distribution of benthic assemblages, from meiofauna to megafauna, on seamounts in the central section of the SWIR between 41S, 42E and 33S, 58E. The benthos of this region is completely unstudied and is of particular interest in terms of its position in relation to major ocean currents, gradients of primary productivity, and recent predictions as to the global distribution of cold-water corals. The specific objectives of JC066 were:
1. To undertake high resolution multibeam surveys of each of five seamounts, Coral, Melville, Middle of What, Sapmer and Atlantis Banks. 2. To undertake 8 ROV Transects at each site 3. Continuous video recording for ROV transects and regular still photos every 100m. 4. Additional dives for specimen collection of megafauna and sampling of macro and meiofauna using blade /box corers. 5. To collect oceanographic data to provide environmental parameters with which to compare biological data. These objectives were only partially achieved because of the replacement of the ROV Isis with the ROV Kiel 6000. The latter was limited to 12 hour operations and was not of the same specification as the former. JC067 was a 'bolt-on' shiptime project, funded by a NERC Small Grant (NE/H012087/1, "Biogeography and ecology of the first known deep-sea hydrothermal vent field on the ultraslow-spreading SW Indian Ridge", to take advantage of the opportunity presented by the location of the ship with an ROV in the Indian Ocean for cruise JC066.The specific objectives of JC067 were: 1. Characterise vent fauna from the SWIR, collecting samples of the dominant fauna for taxonomic identification and phylogenetic analysis, to elucidate the biogeographic affinities of SWIR vent fauna. 2. Test the hypothesis that the lower incidence of hydrothermal venting along ultra slow-spreading ridges may impose a filter on the life-history biology of faunal species at vents. 3. Determine the interannual variability of faunal microdistribution for the first time at a vent field on an ultra slow-spreading ridge, by comparing imagery from JC067 with that obtained by AUV dives in 2007. |
| Chief scientist | Alex David Rogers (University of Oxford Department of Zoology), Jon Copley (University of Southampton School of Ocean and Earth Science) |
| Coordinating body | Natural Environment Research Council (NERC) |
| Cruise report |  (11.83 MB) (3.15 MB) |
| Ocean/sea areas | |
| General | Indian Ocean |
| Specific | Southwest Indian Ridge. Dragon Vent Field. |
| Track charts | (0.13 MB) |
| Measurements | |
| Physical oceanography | |
| Surface measurements underway (T,S) | Quantity: activity duration in days = 35 Description: Surface measurements of chlorophyll and temperature underway |
| CTD stations | Quantity: number of stations = 51 Description: 51 CTDs mainly across seamounts |
| Current profiler (eg ADCP) | Quantity: activity duration in days = 35 Description: Hull-mounted ADCP run throughout the cruise. |
| Current profiler (eg ADCP) | Quantity: number of stations = 51 Description: LADCP mounted on CTD |
| Other physical oceanographic measurements | Quantity: number of profiles = 207 Description: Turbulence profiler run at 4 seamounts (Coral, Melville, Sapmer and Atlantis). Total of 207 profiles measuring pressure, temperature, shear, conductivity and chlorophyll A |
| Chemical oceanography | |
| Oxygen | Quantity: number of stations = 51 Description: 230 dissolved oxygen samples taken for calibration of oxygen sensor and oxygen sensor readings |
| Phosphate | Quantity: number of stations = 51 Description: Samples taken for nitrate/phosphate/POC measurements |
| Nitrate | Quantity: number of stations = 51 Description: Samples taken for nitrate/phosphate/POC measurements |
| Other chemical oceanographic measurements | Quantity: number of stations = 51 Description: 89 salinity samples were taken and measured to calibrate salinity measurements from CTD. |
| Biology and fisheries | |
| Particulate organic matter (inc POC, PON) | Quantity: number of stations = 51 Description: Samples taken for nitrate/phosphate/POC measurements |
| Zooplankton | Quantity: number of hauls = 4 Description: Zooplankton samples from ring net |
| Pelagic bacteria/micro-organisms | Quantity: number of samples = 190 Description: 0.2µm and 3.0µm filters for bacterial samples from CTDs |
| Zoobenthos | Quantity: number of samples = 37 Description: Qualitative meiofaunal samples |
| Zoobenthos | Quantity: number of samples = 8 Description: Coral framework |
| Zoobenthos | Quantity: number of samples = 5 Description: HYBIS grab samples for meiofauna |
| Zoobenthos | Quantity: number of samples = 16 Description: Quantitative samples for meiofauna |
| Zoobenthos | Quantity: number of samples = 6 Description: Megacore samples for meiofauna (shared for macrofauna) |
| Zoobenthos | Quantity: number of samples = 19 Description: Quantitative sediment samples for macrofauna |
| Zoobenthos | Quantity: number of samples = 1709 Description: Zoobenthos collected with ROV Kiel 6000 |
| Zoobenthos | Quantity: number of samples = 53 Description: Non-quantitative sediment samples for macrofauna |
| Acoustic reflection on marine organisms. | Quantity: activity duration in days = 35 Description: EK60 multifrequency acoustic data |
| Other biological/fisheries measurement | Quantity: activity duration in hours = 221 Description: Video data from ROV Kiel, SHRIMP and HYBIS (footage estimated as dive time and does not account for multiple cameras on some vehicles). |
| Geology and geophysics | |
| In-situ seafloor measurement/sampling | Quantity: number of samples = 10 Description: Rock samples obtained from each seamount to determine density of rock. |
| Multi-beam echosounding | Quantity: activity duration in days = 5 Description: EM120 SWATH bathymetry surveys of 5 seamounts, Coral, Melville, Middle of What, Sapmer and Atlantis |
| Gravity measurements | Quantity: activity duration in days = 35 Description: Gravity meter data collected throughout scientific days of the cruise. |
| Moorings, landers, buoys | |
| Biology and fisheries | |
| Other biological/fisheries measurement | 32° 42' 41" S 57° 16' 17" E — Mooring comprising whale bone and wood to study biological colonisation of organic material. |
| Other biological/fisheries measurement | 41° 22' 23" S 42° 54' 35" E — Mooring comprising whale bone and wood to study biological colonisation of organic material. |
