The colorful and diverse ecosystems of shallow coral reefs are threatened by pollution, overfishing, and global warming. Scientists wonder whether the little-studied, dimly lit deep coral reefs may serve as a lifeboat for shallow reefs under stress. Studies are just getting started to rigorously test this "deep reef refuge hypothesis," first proposed in 1996. A recent paper in Science Advances is one of the first, testing whether deep populations of corals might reseed shallow ones. Researchers suspect reseeding may happen in only a few coral species, but say the deep reefs may serve as havens for fish that can swim between habitats.
Author: Kenneth R. Weiss