New Study Reveals Global Ubiquity and Dynamic Nature of Reef Halos

Reef Halos found worldwide

Check out our new paper in American Naturalist - or just the press release - to see what we’ve been working on lately!

In the paper, we document the global ubiquity and dynamic nature of reef halos - shedding light on these large-scale patterns that have captivated scientists for decades.

A bit of background: Reef halos are bands of bare, sandy seafloor that surround coral patch reefs. These features are visible from satellite imagery and can be several meters to several kilometers in width. They are created by the grazing behavior of herbivorous fish and invertebrates, who venture out from the safety of the coral patch reef to eat the algae and seagrass that cover the surrounding seabed. Fear of predators keeps these smaller animals close to the safety of the reef. So the vegetation close to the reef is eaten down to the bare sand, creating a distinct "halo" around the coral reef.

This study revealed that coral reef halos are more common around the world than previously thought, and are quite dynamic, changing in size over relatively short timescales on the order of months, despite persisting for at least half a century. Previous research highlight that reef halos have been associated with marine reserves designed to protect predator and herbivore species from being overfished. So, the very presence of a halo in a given area may be indicative of healthy predator and prey populations providing a valuable, and globally relevant, reef health assessment tool.

We hope our findings can contribute to more efficient and large-scale monirting of the effects of fisheries and marine reserves round the world…stay tuned!