Asterix SERPENT visit report

This report presents the results from the SERPENT project collaborative research with StatoilHydro at theAsterix deep-water exploration oil well, drilled from the Transocean Leader in the Norwegian Sea. Thestudy was designed to investigate seabed disturbance resulting from the drilling activities at Asterix and theeffects of these activities on the benthic environment and megafaunal organisms.The ROV Magnum 018, was used to take eight video transects of at least 100m in length which were usedto assess visually the extent of drill cuttings and to determine megafaunal densities. Also a series sedimentsamples were collected using ROV operated push cores at 50, 80 and 100m from the well to determineheavy metal concentrations, total organic matter and particle size distribution.Comparison of these methods suggested disturbance was variable depending on heading but suggestedcomplete coverage of the seabed up to 60m from the well and partial coverage to 100m. Analysis of thesediment showed elevated Barium concentration in surface sediments at all sample locations, decreasingwith distance and with depth sections. At the site closest to the well mean particle size increased incomparison to the background sediment. These physical changes were associated with significantreductions in megafaunal abundance and changes in the megafaunal community structure, with very fewanimals observed in a 50m radius of the well. Small ophiuroids were extremely abundant at the sitereaching up to 20m-2. Similar to the megafauna, their numbers were reduced by the disturbance event anddensity was significantly reduced within 80m of the well.Details of a short documentary film made by StatoilHydro about the SERPENT collaboration on board theTransocean Leader are also given here