From lightless depths to sunlit surfaces, the species that inhabit Earth's oceans display preferences for different segments of the water column. But most studies of marine species distribution fail to consider these subsurface variations in the seas' vertical ecology.
Seeking to understand potential benefits and tradeoffs from integrating depth as a third dimension in environmental niche models, this research team developed the results of two- and three-dimensional models for 10 species of lanternfish, the most diverse and abundant family (Myctophidae) of offshore fish in the Southern Ocean. Using a total of 2,918 GBIF-mediated occurrences aligned to environmental baseline data for the period 1960–2010, the authors produced three models for comparison across each myctophid species.
Two "simplistic" 2D models stick to the surface, processing both the full dataset and the subset containing depth information while omitting consideration of depth. The third "depth-integrated" 3D model enriched the analysis of the latter subset by retaining the biological bathymetry to place occurrences in one of seven layers of vertical habitat.
After accounting for differences in the sample size of data for each species, the study found considerable overlap between 2D and 3D models across all depth predictions, particularly for depths less than 200 metres. 3D models may be more useful in revealing unrecognized suitable habitat and latitudinal changes in habitat, as species appear to move between shallower waters in the south and deeper ones equatorward. The conclusion echoes a call for well-designed surveys that collect high-quality data, including depth of catch, particularly for species of the middle depths.