RRS James Cook Cruise 36, 19 Jul-28 Jul 2009. The Geobiology of Whittard Submarine Canyon

The biological and geological research programme for James Cook cruise 36 was built around a series of ROV video transects to determine variations in species and community structure and composition in different geological and topographic settings down the canyon. ROV transects were planned to undertake detailed studies of recognised biological hotspots on both hard and soft substrates, to collect specimens for taxonomic studies, including molecular genetics, and to carry out biological experiments, including the use of in situ incubation chambers and tracer feeding experiments to study the physiology of deep-water fauna. Additional coring, CTD and water column particulate sampling programmes were planned to investigate the recent geological history of the canyon, and, in particular, to investigate whether significant sediment is currently accumulating in any part of the canyon, to sample macro- and meiofauna in areas of soft substrate, and to investigate the fate of organic carbon in the canyon. JC36 was highly successful. The cruise built on the successful mapping of the canyon, using swath bathymetry and 30 kHz sidescan sonar, undertaken during JC35. The main achievements of JC36 included the completion of 26 ROV dives, totalling 340 hr. Seafloor video and photographs along 12 transects from the eastern and western canyon branches between 500 and 3600 m waterdepth were collected. A collection of over 240 biological specimens was collected to verify species identification from the video transects. Pushcores for sedimentology, organic geochemistry, biology and microbiology were also collected. Ultra high-resolution swath bathymetry of the canyon floor using the multibeam system mounted on the ROV was collected on 8 dives. A total of 10 dives were dedicated to placing, initiating and recovering a variety of biological experiments on the seafloor, mainly to examine respiration rates of individual animals or animal communities. The coring programme completed 19 successful piston core stations and 29 successful megacore stations. Most of the latter were processed for macrofauna and meiofauna but some were subsampled for sedimentology and geochemistry. A preliminary assessment suggests that most of the sediment recovered is late glacial in age, and that little Holocene sediment has been deposited in the canyon. 6 CTD profiles and 5 SAPS (stand-alone pump) stations were completed to characterise the suspended particulate matter above the canyon floor. A total of 30 pushcores and megacores also sampled for organic geochemistry.