March 2021

Tropical benthic communities at an uninhabited coral reef island in the central Pacific Ocean. Despite marine ecologists knowing a lot about the driving forces of the relative dominance of benthic competitors on tropical coral reefs, we know almost nothing about their patterns of spatial distribution and the forces governing these patterns across seascapes. In Ford et al., we captured thematically resolved benthic data using spatially expansive sub-surface towed-diver image surveys across ~140 linear km of reef around five uninhabited central Pacific oceanic islands. Using spatial statistics, we show benthic competitors are spatially clustered around the circumference of oceanic islands at multiple spatial scales, often dominating entire sections of coastlines to form distinct ecotones. These scaling properties are more consistent between islands in closer proximity and of a similar size, and in some cases correlate with the scaling properties of concurrent gradients in physical drivers like waves and sub-surface temperature. Our findings suggest such physical drivers not only limit or promote the abundance of various benthic competitors on coral reefs, but also play a key role in governing their spatial scaling properties across seascapes. Photo credit: Brian Zgliczynski, Scripps Institution of Oceanography.

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