Other than phytoplankton, nothing is more critical to the health of Earth’s oceans than coral. While world leaders and marine scientists argue over why the coral is dying or disappearing at an alarming rate, one small group of researchers has made history by placing lab-grown coral in the wild where it is reproducing and growing. They could make history again if they’re able to revive the world’s beautiful and critically-needed coral reefs.
According to the report published in the current issue of the Bulletin of Marine Science, the work was conducted by researchers from SECORE (SExual COral Reproduction) International, the University of Amsterdam and the Carmabi Marine Research Station on the island of Curaçao in the Caribbean. They began in 2011 by harvesting specimens of critically endangered elkhorn coral (Acropora palmata). After growing for a year in the lab, the coral was replanted in the same waters and observed by the team. What happened?
In four years, these branching corals have grown to a size of a soccer ball and reproduced, simultaneously with their natural population, in September 2015. This event marks the first ever successful rearing of a threatened Caribbean coral species to its reproductive age.
That’s the excited project assessment by Valérie Chamberland, a coral reef ecologist on the team who works for SECORE. Why were they successful in growing new coral from a lab when other efforts have failed?
Previous attempts used fragments of coral which grew into copies of their parents – somewhat like cloning – which meant the offspring had the same deficiencies as the parents. To promote genetic diversity, SECORE picked male and female gametes (cells) and allowed them to join and grow randomly in the lab to produce genetically unique new corals.
It’s a slow process. The Elkhorn corals reproduce only once or twice a year, most often after a full moon in the month of August. That’s when the team went into the waters to collect the gametes. Elkhorn reach sexual maturity in four years, so when those re-planted from the 2011 harvest started reproducing in the wild in 2015, the project was declared a success.
A success but not a long-term solution, says Dirk Peterson, coral reef expert and director of SECORE.
Our techniques can only support natural recovery, which means that conditions have to be appropriate to allow long term survival of outplanted corals and succession by other organisms to restore ecosystem functions … We don’t get around to protect coral reefs and to apply additional management tools to reduce overfishing, pollution and other threats to coral reefs.
Science alone can’t save the coral and without coral, the oceans and all that depend on them are doomed.