1.8. Benthic Subtidal Ecology

  1. Benthic ecology refers to the communities of animals and plants which live on or in the seabed and the relationships that they have with each other and with the physical environment. The subtidal benthic ecology of the Array was characterised via a series of site-specific surveys using grab sampling, underwater video and benthic trawls.
  2. The site-specific surveys indicated that seabed within the site boundary supports a benthic assemblage typical of this area of the North Sea. Offshore subtidal sands and gravels and subtidal sands and gravels represented the main seabed habitats, supporting a range of species such as sea urchins, bivalves, polychaetes (a class of segmented worms often known as bristleworms) and brittle stars. For the purposes of this assessment, Important Ecological Features (IEFs) were defined based on the results of the site-specific survey and the baseline collated through desktop data sources. These IEFs were:
  • Offshore subtidal sands and gravels;
  • Subtidal sands and gravels;
  • ocean quahog;
  • phosphorescent sea pen;
  • sea tamarisk; and
  • dead man’s fingers.
  1. A number of potential impacts on benthic subtidal ecology associated with all phases of the Array were identified. These included:
  • temporary and long term habitat loss and disturbance in all phases;
  • increased risk of Invasive Non-Native Species (INNS) in all phases;
  • increased SSCs and associated deposition in all phases;
  • potential effects of Electromagnetic Fields (EMFs) in the operation and maintenance phase;
  • colonisation of hard structures in the operation and maintenance phase; and
  • removal of hard structures in the decommissioning phase.
  1. With the proposed designed in measures in place, all of these impacts result in effects of minor significance, which is not significant in EIA terms.
  2. Cumulative impacts arising from the Array together with other projects and plans were assessed and predicted to result in effects of minor significance upon benthic subtidal ecology, which is not significant in EIA terms.
  3. No likely significant transboundary effects with regard to benthic subtidal ecology from the Array on the interests of EEA states were predicted.