A rare breed of coral was successfully bred in a lab by scientists. Not only did this provide new insight into the juvenile form of the species, but it could also help scientists figure out how to save the species in the wild.
Currently, we don't know much about this particular species of coral, the Caribbean Pillar Coral Dendrogyra cylindrus. Scientists haven't seen the small juvenile form of the coral in over 30 years, thanks to it being overshadowed by another coral in the area, the more common and more studied 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," says Kristen Marhaver from the CARMABI Foundation on the Caribbean island of Curaçao and lead author of the study. "It was literally right under our noses for years."
However, the pillar coral is important in the area as it forms large branches that specific fish species often find shelter under. These branches also help protect those fish and other organisms beneath it from surges associated with storms in the area.
The smokestack-shaped pillar corals are also different, at least in their mating. Most corals are both male and female and release both eggs and sperm. However, pillar corals are either one or the other, with male and female colonies separated from each other. The male colonies release sperm into the water which eventually meets with eggs released by female colonies. And this only happens at very specific times.
Researchers collected eggs and sperm from pillar corals by precisely timing their collection: three nights after a full moon in August, 100 minutes after sunset. They used nets to collect eggs and syringes to collect sperm. They combined eggs and sperm in a lab and carefully prodded the eggs to become swimming larvae. This is the first time human eyes have seen this particular stage of pillar coral growth.
Once researchers placed the swimming larvae into water tanks, they grew into juveniles and lived about seven months.
Now that this process is successful, researchers can start focusing on testing certain conditions, such as those associated with climate change, on the growth cycle of this coral. They also hope that they can place some of these lab-grown coral back in the ocean and repopulate areas where they've become scarce.
However, researchers feel that just knowing that these corals can reproduce is a large hurdle now tackled.
"Corals can also reproduce by fragmentation, so a huge field of pillar corals could in fact be from one single parent colony and might not be able to reproduce," says Marhaver. "Now that we have some of the first solid evidence that they are still able to reproduce, it means we can be cautiously optimistic about the future of this threatened species."
