A study by the Curacao-based CARMABI Foundation has provided the first photos and documentation of juveniles of this species and could provide information to help bolster local coral reef conservation.
The three-member team also plans to ‘out-plant’ the lab-grown juveniles in the wild which could help populations become more resilient to climate change.
Team leader Kristen Marhaver said the Caribbean Pillar Coral Dendrogyra cylindrus is rare and understudied, and small juveniles of this species have never been seen in over 30 years of surveys in the Caribbean.
She said the species is one of very few corals in the Caribbean that forms large branches, which can provide shelter for important fish species and reduce the energy of storm surge as it approaches shore.
“Strangely enough, pillar corals happen to spawn just half an hour before another threatened coral that is far better studied – the elkhorn corals.
“So the reason why for so many years we’ve never witnessed spawning pillar corals is that, while they were spawning, virtually all coral spawning researchers and photographers in the Caribbean were on their boats doing final preparations on their dive gear for elkhorn coral spawning. It was literally right under our noses for years,” Marhaver said.
Pillar Corals form a unique ‘smoke stack’ shape like no other coral species, and they display unusual mating behaviour compared to most spawning coral species. Most spawning corals are hermaphrodites that release large bundles of eggs and sperm.
Pillar corals, which only spawn on a few specific nights of the year, build colonies that are either all-male or all-female. The males first release sperm into the seawater, shortly followed by the females releasing their individual eggs. This makes collection and breeding research extremely difficult.
“Now that we’ve successfully reared juvenile Pillar Corals in the lab, not only can we study them in more detail to find out what factors could be threatening their survival in the wild, but it also means that we can try to out-plant a small number back to the reef.
“We don’t know if this will work and it is certainly not a cure-all for the reef. But especially in such a rare coral species, a tiny boost of a few new individuals could make a big difference in their genetic diversity, allowing their populations to adapt and become more resilient to the changing environment in the oceans,” said Marhaver.
The research team included Mark Vermeij from the CARMABI Foundation and the University of Amsterdam, and Mónica Medina from Pennsylvania State University. The research was funded by the US National Science Foundation with permissions from the Curacao government.