The 3-dimensional structure of habitats is a critical component of
species' niches driving coexistence in species-rich ecosystems. However,
its influence on structuring and partitioning recruitment niches has not
been widely addressed. We developed a new method to combine Species
Distribution Modeling and Structure from Motion and characterized
three-dimensional recruitment niches of two ecosystem engineers on
Caribbean coral reefs, scleractinian corals and gorgonians. Fine-scale
roughness was the most important predictor of suitable habitat for both
taxa, and their niches largely overlapped, primarily due to
scleractinians broader niche breadth. Crevices and holes at mm-scales on
calcareous rock with low coral cover were more suitable for octocorals
than for scleractinian recruits, suggesting the decline of scleractinian
corals is facilitating the recruitment of octocorals on contemporary
Caribbean reefs. However, the relative abundances of the taxa were
independent of the amount of suitable habitat on the reef, emphasizing
niche-processes solely do not predict recruitment rates.