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Chevron Rosebank SERPENT final report

By D.O.B. Jones, C.N. Roterman and A.R. Gates

Abstract

This report presents the results from the SERPENT project collaborative research with Chevron at the<br/>Rosebank deep-water exploration site. SERPENT visited the Stena Carron drill ship in the Faroe Shetland<br/>Channel (FSC) to investigate megafaunal diversity at the seabed (1124m depth) and determine the effects of<br/>disturbance resulting from the drilling activities on the seabed and benthic organisms.<br/>The Magnum 156 remotely operated vehicle (ROV), was used to take eight video transects of at least 100m<br/>in length which were used to assess visually the extent of drill cuttings and to determine megafaunal<br/>densities. Sediment samples were also collected using ROV operated push cores at 250 and 400m from the<br/>well to determine heavy metal concentrations, total organic matter and particle size distribution.<br/>These methods suggested disturbance was variable depending on heading but drill cuttings completely<br/>covered the seabed 70m from the well and there was partial coverage to approximately 100m. Analysis of<br/>the sediment showed elevated Barium concentration in surface sediments close to the well. These physical<br/>changes were associated with significant reductions in megafaunal abundance and changes in the<br/>megafaunal community structure, with very few animals observed in a 60m radius of the well.<br/>In addition, specimens of the characteristic megafauna were collected and physical data from the water<br/>column was logged. An experiment was carried out to investigate bioturbation rate in disturbed and<br/>undisturbed sediment. Luminophore tracer particles were added to the sediment surface in corrals which<br/>were either controls or treated with a sedimentation disturbance event. The sediment was later sampled and<br/>sectioned for subsequent analysis

Topics: QH301
Publisher: National Oceanography Centre Southampton
Year: 2010
OAI identifier: oai:eprints.soton.ac.uk:160967
Provided by: e-Prints Soton
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