Global Habitat Suitability for Framework-Forming Cold-Water Corals - Environmental Data

Environmental data layers used in the production of global habitat suitability models for several species of Scleractinian corals from the publication:

Davies, A.J. & Guinotte, J.M. (2011) Global Habitat Suitability for Framework-Forming Cold-Water Corals. PLoS ONE 6(4): e18483. doi:10.1371/journal.pone.0018483

Files are ASCII raster layers, zipped using 7zip. Each raster has a WGS 1984 coordinate system.

Brief methodology and outline of variables provided are presented below, for full details refer to the above manuscript in PLoS ONE:

Terrain variables

Several terrain attributes were extracted from the SRTM30 data (Table 1) following techniques and algorithms described in Wilson et al (2007). Individual approaches are described within the footnote of Table 1, however, briefly the extraction process and description of each variable is described here. Bathymetric position index (BPI) is an approach to determine topographical features based on their relative position within a neighbourhood, and can be calculated over fine or broad scales to capture smaller or larger terrain features respectively. This calculation has been developed into an ArcGIS tool by Wright et al. (2005). Slope was calculated using DEM Tools for ArcGIS developed by Jenness (2012), in particular the 4-cell method of calculating slope, which is accepted as the most accurate approach (Jones 1998). In this manuscript, slope is defined as the gradient in the direction of the maximum slope. Curvature attempts to describe terrain features and may provide an indication of how water would interact with the terrain. In this manuscript, plan and tangential curvature can describe how water would converge or diverge as it flows over relief, whilst profile curvature describes how water would accelerate or decelerate as it flows over relief (Jenness 2012). Aspect is defined as the direction of maximum slope and was converted to continuous radians following Wilson et al. (2007). Rugosity, terrain ruggedness index and roughness all generally describe the variability of the relief of the seafloor (Wilson et al. 2007). Rugosity is defined as the ratio of the surface area to the planar area across a neighbourhood of a central pixel (Jenness 2012). Terrain ruggedness index is defined as the mean difference between a central pixel and its surrounding cells and roughness which is the largest inter-cell difference of a central pixel and its surrounding cell (Wilson et al. 2007).

Environmental variables

Environmental variables were created using the variable up-scaling approach presented within (Davies & Guinotte 2011). This approach takes gridded layers of an environmental variable and drapes them over bathymetry to provide an indication of conditions near the seabed, it has been proven to work well over global and regional scales (Davies & Guinotte 2011, Guinotte & Davies 2012). In this manuscript, these environmental layers must be considered as representations of general conditions, as likely, the highly variable topography of the canyon will not yield a good prediction of environmental variables at such a small spatial scale. Limited CTD profiles were collected using a SeaBird 911+, collating data for turbidity (Seapoint, formazin turbidity units), dissolved oxygen (mg L-1), depth (m), conductivity (Siemens/m), temperature (°C), salinity, and pH. These casts were compared with the modelled layers (specifically dissolved oxygen, salinity and temperature) to determine their relative accuracy for certain areas of the seafloor

Variable name // Filename // Units // Reference (see original paper)

Terrain Variables

Aspect // aspect // Degree // Jenness (2012)
Aspect – Eastness // eastness //  //  Wilson et al. (2007)
Aspect – Northness // northness //  // Wilson et al. (2007)
Bathymetry // srtm30 // m  // Becker et al. (2009)
Curvature – Profile // profilecurve //  // Jenness (2012)
Curvature – Plan // plancurve  //  // Jenness (2012)
Curvature – Tangential // tangcurve  //  // Jenness (2012)
Roughness // roughness  //  // Wilson et al. (2007)
Rugosity // rugosity  //  // Jenness (2012)
Slope  // slope  // Degrees // Jenness (2012)
Terrain Ruggedness Index // tri // //  Wilson et al. (2007)
Topographic Position Index // tpi //  // Wilson et al. (2007) 

Environmental variables
Alkalinity // alk_stein // μmol l-1 // Steinacher et al. (2009)
Apparent oxygen utilisation // woaaoxu // mol O2 m-3 // Garcia et al. (2006b)
Chlorophyll a // modismin, modismean, modismax // mg m-3 // NASA Ocean Color
Dissolved inorganic carbon // dic_stein // μmol l-1 // Steinacher et al. (2009)
Dissolved oxygen // woadiso2 // ml l-1 // Garcia et al.(2006a)
Nitrate // woanit // μmol l-1 // Garcia et al. (2006b)
Omega aragonite // arag_stein // ΩARAG // Steinacher et al. (2009)
Omega aragonite  //  arag_orr // ΩARAG // Orr et al. (2005)
Omega calcite // calc_stein // ΩCALC // Steinacher et al. (2009)
Omega calcite  // calc_orr // ΩCALC // Orr et al. (2005)
Percent oxygen saturation // woapoxs // % O2S  // Garcia et al. (2006b)
Phosphate  // woaphos // μmol l-1 // Garcia et al. (2006b)
Regional current velocity  // regfl // m s-1 // Carton et al. (2005)
Salinity // woasal // pss // Boyer et al. (2005)
Silicate  // woasil // μmol l-1 // Garcia et al. (2006b)
Seasonal variation index  // lutzsvi //  // Lutz et al. (2007)
Temperature // woatemp // °C // Boyer et al. (2005)
Particulate organic carbon  // poc // g Corg m-2 yr-1 // Lutz et al. (2007)
Vertical current velocity //  vertfl // m s-1 // Carton et al. (2005)
Vertically generalised productivity model // vgpmmin, vgpmmean, vgpmmax // mg C m-2 d-1 // Behrenfeld and Falkowski (1997)