RRS James Cook Cruise 44, 25 Mar - 22 Apr 2010, Trinidad to Jamaica. Hydrothermal activity and deep-ocean biology of the Mid-Cayman Rise

JC044 was a NERC funded research cruise aboard the UK Research Vessel the RRS James Cook the aim of the cruise was to explore the ultra-slow spreading Mid-Cayman Rise (MCR) in the Caribbean for hydrothermal activity. The MCR is the deepest spreading centre on the Earth and is isolated from the contiguous Mid-Atlantic Ridge, the closest mid-ocean spreading centre. The discovery of hydrothermal activity in this area would help us address the scientific questions related to the biogeography of hydrothermal vent organisms, the effect of high pressures on the chemistry of hydrothermal vents and the geological settings of any vents located. We successfully identified 2 active hydrothermal systems with associated chemosynthetic communities. One site named Beebe, after William Beebe, the first man to observe deep-sea marine organisms in situ. The Beebe vent field is at a depth of around 5000m and is the deepest hydrothermal site ever discovered. The second vent site is on top of an ocean core complex, it exhibits unusual chemical properties and we have named this site the Von Damm vent field after the recently deceased Karen Von Damm, a groundbreaking hydrothermal geochemist. After extensive work in the southern area of the ridge we found no evidence of hydrothermal activity, earlier reported evidence (German et al., 2010) may be re-suspended sediment material.