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Keywords:

  • Cold-water coral;
  • deep sea;
  • habitat;
  • Irish continental margin;
  • Lophelia pertusa ;
  • marine spatial planning;
  • Maxent;
  • predictive modelling;
  • vulnerable marine ecosystems

Abstract

Aim

The distribution of vulnerable marine ecosystems in the deep sea is poorly understood. This has led to the emergence of modelling methods to predict the occurrence of suitable habitat for conservation planning in data-sparse areas. Recent global analyses for cold-water corals predict a high probability of occurrence along the slopes of continental margins, offshore banks and seamounts in the north-eastern Atlantic, but tend to overestimate the extent of the habitat and do not provide the detail needed for finer-scale assessments and protected area planning. Using Lophelia pertusa reefs as an example, this study integrates multibeam bathymetry with a wide range of environmental data to produce a regional high-resolution habitat suitability map relevant for marine spatial planning.

Location

Irish continental margin (extended continental shelf claim).

Methods

Maximum entropy modelling was used to predict L. pertusa reef distribution at a spatial resolution of 0.002°. Coral occurrences were assembled from public databases, publications and video footage, and filtered for quality. Environmental predictor variables were produced by re-sampling of global oceanographic data sets and a regional ocean circulation model. Multi-scale terrain parameters were computed from multibeam bathymetry.

Results

Suitable habitat was predicted on mound features and in canyon areas along a narrow band following the slopes of the Irish continental margin, the Rockall Bank and the Porcupine Bank. Standard deviation of the seabed slope (54%), temperature (28%) and bottom shear stress (9%) were the most important variables to predict coral distribution.

Main conclusions

This is the first regional coral habitat suitability modelling study to incorporate full coverage multibeam bathymetry in the deep sea. The use of high-resolution environmental data and quality-controlled distribution data significantly reduces habitat overestimation demonstrated by global-scale analyses and produces detailed maps to support marine protected area network design. The strong response of the corals to local-scale terrain variability highlights the need to protect the seabed from anthropogenic impacts that may reduce its complexity, such as bottom trawling.