Table 3 Candidate environmental predictors used for the habitat-based density modelling.

From: Deep ocean drivers better explain habitat preferences of sperm whales Physeter macrocephalus than beaked whales in the Bay of Biscay

Variables used in the study with abbreviations and units

Original Resolution

Sources

Effects on pelagic ecosystems of potential interest to deep-divers

Static

   

  Depth (m)

15 arc sec

A

Deep-divers feed on squids and fish in the deep-water column

  Slope (°)

15 arc sec

A

Associated with currents, high slopes induce prey aggregation or enhanced primary production

  Roughness (m) –

15 arc sec

A

A high roughness indicates an important escarpment and a greater richness in prey

  Surface of canyons – CanArea (km2)

15 arc sec

B

Deep-divers are often associated with canyons and seamounts structures

Dynamic

   

  Mean and standard deviation of temperature – mTd1-d2 and sdTd1-d2 (°C)

0.083°, daily

C

Variability over time and horizontal gradients of temperatures reveal front locations, potentially associated with prey aggregation or enhanced primary production

  Mean and standard deviation of gradients of temperatures – mGrTd1-d2 and sdGrTd1-d2 (°C)

0.083°, daily

C

 

  Mean and standard deviation of eddy kinetic energy – mEKEd1-d2 and sdEKE 1-d2 (m2.s-2)

0.083°, daily

C

High EKE relates to the development of eddies and sediment resuspension inducing prey aggregation

  1. A: https://www.gebco.net/; 15 arc-second is approximately equal to 0.004°. B: Harris et al. 62. C: Iberian Biscay Irish- Ocean Physics Reanalysis model from Copernicus (https://doi.org/10.48670/moi-00029). All dynamic variables were extracted or computed for each depth class (surface, 0–200 m, 200–600 m and 600–2000 m). Abbreviations used in the following article are defined here in bold, d1-d2 refers to the depth classes e.g. 200–600 means between 200 and 600 m. In the analyses, all variables were resampled or used at a 0.083° spatial resolution.
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