A new programme to exchange coral larvae across the Caribbean has been launched to support reef restoration and increase genetic diversity in declining Caribbean coral populations.
The Caribbean Coral Larvae Exchange Program, led by SECORE and supported by Revive & Restore, a conservation group specialising in the genetic recovery of endangered species, will transport coral larvae across their natural ranges, thereby increasing genetic diversity among existing populations.
Coral populations across the Caribbean have declined in recent years, in large part due to an ongoing outbreak of Stony Coral Tissue Loss Disease (SCTLD) and a succession of bleaching events caused by elevated sea temperatures, particularly on reefs off the coast of Florida.
Increased coral mortality during these events has reduced the number of healthy colonies available for reproduction, while at the same time increasing the separation between those that remain viable.
These factors increase the risk of inbreeding among colonies, creating successive generations that are less able to resist disease or changes in water temperature.
‘Coral populations – when reproducing successfully on their own – used to exchange larvae naturally across reefs and islands,’ said Dr Margaret Miller, SECORE’s Chief Science Officer.
‘As these populations have become so much smaller, this natural exchange is not happening, and our assistive breeding efforts are hampered by having too few parent colonies to work with in individual locations.’
The critically endangered elkhorn coral (Acropora palmata), a fast-growing species that forms large branching structures in shallow water, has been identified as one of the key target species for the programme.
Once dominant across shallow Caribbean reefs, the species has declined sharply in recent years and is now absent or reduced in many areas.
In Floridian waters, Elkhorn coral has been described as ‘functionally extinct’, meaning that remaining colonies are now too small and fragmented to reproduce effectively.
‘In a region as small and interconnected as the Caribbean, coral populations and the threats they face cut across international borders, and so should our interventions,’ said Dr Liv Liberman, Revive & Restore’s Director for Ocean and Climate.
‘Revive & Restore advances genetic rescue for endangered species by developing new biotechnologies and integrating them into conservation practice, but new tools are only as powerful as the trust, partnerships, and regulatory pathways that allow them to be responsibly implemented.
‘The Caribbean Coral Larvae Exchange Program is a strategic investment in this kind of regional infrastructure, building relationships among restoration practitioners and establishing the legal and institutional frameworks to advance coordinated coral population management across the region.’
A workshop held in Punta Cana, Dominican Republic, in March brought together coral restoration organisations from across the Caribbean, including groups from the Dominican Republic, Honduras, Bonaire, Colombia, the United States and the US Virgin Islands.
Each of the organisations involved will act as both donors and recipients of coral larvae, ensuring that species diversity is extended in each region.
Pilot exchanges of larvae are planned to take advantage of the Caribbean coral spawning season in August, although there are regulatory hurdles to be overcome, as transportation of coral larvae is regulated by the Convention on International Trade in Endangered Species (CITES) and the Nagoya Protocol, which governs the transfer of genetic material across national boundaries.
‘In line with international agreements, governments in the Caribbean region have adopted important legal safeguards aimed to prevent excessive and unfair exploitation of corals and other wild species,’ said Steven Broad, a wildlife trade specialist involved in the programme.
‘The planned coral exchanges have a clear conservation purpose, but we still need to secure approval under relevant laws and regulations, which vary from country to country in the region.’
Organisers say the programme will take time to deliver results, but could contribute to strengthening coral populations across the region over the longer term.
‘Coming out of our workshop discussions, there was a strong consensus that implementing larvae exchange will be challenging but definitely not impossible,’ said Dr Miller.
‘We think it is important to start as soon as possible, since it will take time for the successfully exchanged larvae to become part of the local brood population,’ she said, adding, ‘In five years, we aim to have new parent corals interbreeding in many places throughout the Caribbean.’
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