Submarine power transmission cables placed on or buried in the seabed have a wide range of potential impacts on the marine environment due to their installation (i.e. initial placement, repair, and recovery) as well as their operation. These impacts vary in spatial extent, duration, frequency, and reversibility. Potential effects arising from cable installation include benthic habitat destruction, disturbance and damage to fauna, and increased sedimentation from the cables themselves and noise, visual disturbance, waste, and emissions from the supporting vessels and cable laying machinery ( OSPAR Commission, 2009). Potential effects associated with cable operation include introduction of artificial hard substrate, electromagnetic field generation, and thermal radiation ( OSPAR Commission, 2009 and Boutillier et al., 2010), the latter having the potential to change sediment biogeochemistry leading to low-oxygen zones, especially in cases where cables are placed close together in an array ( Meissner and Sordyl, 2006).