Acropora palmata Propagation Guide
Propagating elkhorn coral (Acropora palmata), a Critically Endangered Caribbean coral propagated through conservation aquaculture: fragmentation in ocean and land nurseries and outplanting to high-energy reef zones.
Overview
Acropora palmata, the elkhorn coral, is a Caribbean reef-builder whose hard, antler-like structures form many broad, flattened branches resembling elk antlers. It is found throughout the Bahamas, Florida, the Caribbean and to the northern shores of Venezuela, in shallow water from about 1 to 5 metres deep. It thrives best in high-energy zones where wave action is frequent, since wave action increases fragmentation and allows more new colonies to form.
Reproductive Mode
Elkhorn coral reproduces primarily through fragmentation, where fragments break off during storms and form genetically identical colonies. Restoration aquaculture relies on this same asexual process to multiply the species in nurseries.
Fragging / Asexual Propagation
Restoration programmes fragment branches from donor colonies and grow the frags in offshore or land-based nurseries before outplanting them onto degraded reefs. Elkhorn grows quickly, averaging 5 to 10 cm per year and up to 13 cm of branch length a year in healthy colonies, so nursery-grown frags reach outplant size relatively fast.
- Branches are fragmented from healthy donor colonies within a restoration programme.
- Frags are mounted in ocean nurseries on structures or suspended supports, or in land tanks.
- Frags are grown out to a robust size before outplanting.
- Colonies are outplanted into shallow, high-energy reef zones where the species naturally thrives.
Conditions for Propagation
Elkhorn needs strong water movement and bright light, reflecting its natural shallow wave-zone habitat. As an Acropora it requires stable temperature, salinity, alkalinity, calcium and magnesium; warming waters drive bleaching, so stability is critical for healing frags.
Sexual Reproduction
Sexual reproduction occurs via broadcast spawning once per year, after a full moon in late summer, during July, August or September. Restoration programmes use spawning to add genetic diversity beyond fragmentation.