Water samples were collected from a site (521490N, 151450W) in the Rockall Trough region of the north-east Atlantic during the RV Celtic Explorer cruise CE04inOctober 2004. Samples were taken from a depth of 3170 m using a CTD Niskin rosette (General Oceanics, USA). The retrieval of the CTD Niskin rosette took 1 h to passage from sampling depth to surface. Once retrieved samples were immediately transferred to a 4 1C laboratory onboard the research vessel. Enrichment experiments were established within 2 h of sample recovery