Sea Urchins' Impacts on Coral Reefs

A decline in the population of Diadema setosum, a key sea urchin species, between 1998 and 2001 correlated with reduced coral growth in the Sanganeb Marine National Park and Dungonab Bay – Mukkawar Island Marine National Park. This long-spined urchin plays a dual role: at moderate densities (e.g., 16 individuals per m²), it promotes coral growth by creating fresh surfaces for settlement while grazing on algae, but excessive populations can disrupt reef ecosystems by removing coral larvae and overfeeding on algae. Observations near Dungonab Bay revealed that high Diadema concentrations often coincided with declines in healthy coral colonies like Galaxea, highlighting the species' paradoxical impact on reef dynamics.

Vine, P. J. (2023). Sea Urchins’ Impacts on Coral Reefs. Growth and Decay of Coral Reefs, 52–54. https://doi.org/10.1201/9781003335795-12