When the population of these sea urchins is at a healthy level, they are the main grazers which prevent algae overgrowth of the reef.

Diadema antillarum is still, in some tropical areas, one of the most abundant, widespread, and ecologically important shallow-water sea urchins.

It also has an overall negative effect on coral reef resilience, which encompasses the ability of a system to resist and recover from changes stemming from perturbation events.

Recent studies done in Discovery Bay, Jamaica,[4] and other locations[5] appear to show a massive comeback of Diadema, and great regeneration of the reefs.

As of 2015 populations are densest in the eastern Caribbean at Jamaica, Barbados, Dominica, and Puerto Rico, while either remaining virtually stable at low values or showing small increases on the coast of Central America and in Cuba, Florida, the Bahamas, the Virgin Islands, and Curaçao.

[6] When the sea urchins died due to an unknown disease, the biodiversity of the marine life of the coral reefs suffered a great deal.

The resulting lush algae growth stunted and even reversed the development of coral, and the fish and other animals living on the reefs declined in numbers due to less food and shelter.

The reduced biodiversity of the coral reefs affected tourism in several small countries, which depended on the natural beauty of their reefs to help attract visitors, and because tourism was a major part of the income for these countries, the decreased flow of guests stressed their economy.

The increase in population can also be aided by the artificial building of reefs: material such as concrete can encourage the growth of coral, and provide more niches for the urchins to hide from predators such as larger fish.