Elkhorn Coral (Acropora palmata)

Status: needs expert review. Conservation claims cite IUCN, NOAA Fisheries, and CITES; a science reviewer should confirm the assessment and figures before approval. Elkhorn coral (Acropora palmata) is a fast-growing, branching reef-builder and historically one of the most important shallow-water reef corals in the Caribbean.

At a glance

Field	Value	Source
Scientific name	Acropora palmata	WoRMS / authority
Guild	reefs (reef-building coral)	—
IUCN status	Critically Endangered (assessment 2022)	IUCN Red List
Population trend	Decreasing — declines estimated at ~90–95% since 1980 where quantified	IUCN / literature
US protection	Threatened under the Endangered Species Act (listed 2006)	NOAA Fisheries
International trade	CITES Appendix II (Acropora spp.)	CITES
Range	Caribbean, Florida, Gulf of Mexico, western Atlantic	IUCN Red List

Identification

A branching, flattened coral whose broad antler-like ("elkhorn") branches grow rapidly toward the light, forming dense stands in shallow, high-energy reef zones. Colonies build three-dimensional reef structure on the wave-exposed reef crest.

Ecology and role

Elkhorn coral is a colonial animal living in symbiosis with photosynthetic algae (zooxanthellae); heat stress can break that symbiosis and cause bleaching (NOAA Fisheries). Its rapid growth made it a primary builder of shallow Caribbean reef framework, creating the wave-breaking reef crest and the complex habitat that shelters fish and invertebrates — a habitat-forming, foundation role. Detailed claims should be cited to published research and confirmed in review.

Conservation status and threats

Elkhorn coral is Critically Endangered on the IUCN Red List (IUCN). Catastrophic outbreaks of white-band disease beginning in the late 1970s started multi-decade declines; warming seas, marine heatwaves and bleaching, water pollution, and hurricanes compounded them, with reductions estimated at roughly 90–95% since 1980 in areas where loss has been quantified (IUCN; literature). In the United States it has been listed as Threatened under the Endangered Species Act since 2006 — elkhorn and staghorn corals were the first species protected under the ESA explicitly because of the effects of climate change (NOAA Fisheries). More broadly, the IUCN reported in 2024 that over 40% of reef-building coral species face extinction (IUCN). The dominant ongoing stressor is heat stress: the Coral Reef Watch dataset is the early-warning signal for exactly this threat.

How to observe responsibly

This page does not provide approach guidance. Coral is fragile and easily killed by contact. Never touch, stand on, or kick coral; maintain neutral buoyancy and stay clear of shallow reef crests; never collect coral (and note CITES restrictions). Follow the reviewed observation guide and local marine-park rules. Reef-restoration sites are sensitive — keep to regional granularity (ETHICS.md).

How you can help

• Log reef condition and coral sightings via recognized programs such as Reef Check or iNaturalist.
• Support coral-restoration and disease-response programs run by credible organizations.
• Reduce heat-stress drivers: the deepest help for coral is climate action.