RRS James Cook JC055
Cruise summary report
| Cruise Info. | |
| Ship name (ship code) | RRS James Cook (740H) |
| Cruise identifier | JC055 |
| Cruise period | 2011-01-14 — 2011-02-22 |
| Status | Completed |
| Port of departure | Punta Arenas, Chile |
| Port of return | Punta Arenas, Chile |
| Purpose | Research |
| Objectives | The whole programme of JC055 changed with the extensive damage to the ROV Isis on day 5 of the 42-day cruise. As a result Plan B, an over-the-side science programme was put in place and sampling with CTD/SAPs, Megacore, gravity cores and SHRIMP. This limited a number of aspects of the sampling and visual observation of the seabed but resulted in a programme that achieved a remarkably high proportion of the objectives of the cruise. In the Bransfield St, some hydrothermal activity was observed at Hook Ridge, together with areas of reducing sediment but no areas of extensive hydrothermal activity. A Middle Sister a small anomaly in the Eh readings on the CTD suggested hydrothermal release but visual observation of the seabed showed only sedimented and old areas of pillow lava. At the Axe (aka Edifice A), despite extensive CTDs, there was no evidence of any modern hydrothermal activity. At the three sites we did obtain excellent samples for geochemical and water analysis, as well as samples for microbial analysis, macrofaunal and isotope analysis. Megafauna and mosaic analysis was not possible because of the loss of use of Isis. On moving to the East Scotia Ridge at E9 we were able to use SHRIMP to locate the Twin Peaks area (first sighted in 2009) and obtain a third annual set of images over a specified area. Additional exploration did not find any additional vents to those found on JC42. Water column sampling in the plume for chemistry and microbiology was successful. At the Kemp seamount crater, there were successful stations for water chemistry and microbiology. A long SHRIMP transect over the venting area within the caldera was particularly successful and this together with fine scale mosaicing gave a clear map of this venting field. Planned fine scale sampling and ROV swath could not be completed. A SHRIMP transect at the nearby recently mapped Adventure caldera discovered a small vent site on the southern side of the crater. Lastly, we returned to the putative cold seep site off the southwestern end of South Georgia. High CH4 levels in the water column and reduced sediment in cores suggested methane release but two SHRIMP surveys revealed no evidence of surface expression of a cold seep. |
| Chief scientist | Paul A Tyler (University of Southampton School of Ocean and Earth Science) |
| Project | Chemosynthetically-driven Ecosystems in the Southern Ocean: Ecology and Biogeography (ChEsSo) |
| Coordinating body | School of Ocean and Earth Science, University of Southampton |
| Cruise report |  (3.35 MB) |
| Ocean/sea areas | |
| General | South West Atlantic Ocean (limit 20W) Southern Ocean |
| Specific | Bransfield Strait, the East Scotia Ridge and the Kemp Seamount Calderas |
| Track charts | (0.08 MB) |
| Measurements | |
| Physical oceanography | |
| CTD stations | Quantity: number of profiles = 2 Description: Two CTD 2500m vertical casts (Sal. Temp, oxygen, Transp, Eh, LSS) at stations 83 and 84 |
| CTD stations | Quantity: number of profiles = 50 Description: CTD vertical stations 2, 28, 39, 46, 52-53, 55-80, 82-89, 91, 93, 95-96, 101-102, 104-105, 109-110 |
| Subsurface temperature and salinity measurements | Quantity: track kilometres = 67 Description: CTD Towyo (351 profiles in total) at stations 5, 8, 9, 10, 27, 41, 43, 44, 45 |
| Chemical oceanography | |
| Other chemical oceanographic measurements | Quantity: number of stations = 6 Description: SAPS. 30cm filter. |
| Biology and fisheries | |
| Pelagic bacteria/micro-organisms | Quantity: sample litres = 240 Description: Background water from CTD station 82. Water filtered on board. Samples were stored on either 47mm 0.2 micrometre nitrocellulose filters at -80C; 25mm 0.2 micrometre isopore membrane filters at -80C; 50ml tubes at -80C or 4C |
| Pelagic bacteria/micro-organisms | Quantity: sample litres = 740 Description: Plume samples to be analysed by molecular analysis for microbes. Water filtered on board. Samples were stored on either 47mm 0.2 micrometre nitrocellulose filters at -80C; 25mm 0.2 micrometre isopore membrane filters at -80C; 50ml tubes at -80C or 4C |
| Pelagic bacteria/micro-organisms | Quantity: sample litres = 1260 Description: CTD water samples to be analysed by molecular analysis for microbes. Water filtered on board. Samples were stored on either 47mm 0.2 micrometre nitrocellulose filters at -80C; 25mm 0.2 micrometre isopore membrane filters at -80C; 50ml tubes at -80C or 4C |
| Pelagic bacteria/micro-organisms | Quantity: number of image series = 7 Description: SHRIMP video platform at stations 17, 47, 90, 94, 103, 123-124. All videos to be analysed with ARCGIS. |
| Benthic bacteria/micro-organisms | Quantity: number of samples = 14 Description: Megacore sediment, 1cm slice from 50ml tube. |
| Zoobenthos | Quantity: number of samples = 5 Description: 50-200ml vials at USNEL box core Stn 36 |
| Zoobenthos | Quantity: number of samples = 23 Description: 20-500ml vials at Agassiz trawl stn 37 |
| Zoobenthos | Quantity: number of samples = 2 Description: 500ml vials at Usnel box core stn 38 |
| Zoobenthos | Quantity: number of samples = 27 Description: 500ml vials taken at Megacore stations to be analysed for taxonomy |
| Geology and geophysics | |
| Core - soft bottom | Quantity: number of cores = 2 Description: Boxcore at stations 36 and 38 |
| Core - soft bottom | Quantity: number of cores = 40 Description: Megacore for geochemical analysis at stations 11-16, 18-26, 30-35, 48-51, 77, 81, 92, 97-99, 111-113, 117-122 |
| Core - soft bottom | Quantity: number of cores = 6 Description: Gravity cores at stations 29, 106-108, 114-115 |
