Thursday, March 19, 2015

Scientists Catch Up On The Sex Life Of Coral To Help Reefs Survive

For the first time, biologists have caught a rare type of coral in the act of reproducing, and they were able to collect its sperm and eggs and breed the coral in the laboratory. 

The success is part of an effort to stem the decline in many types of coral around the world.

To understand how this works, you need to know that coral reefs are actually colonies of tiny organisms encased in hard skeletons. In many kinds of coral, the whole colony reproduces at once, in a spectacular event called "broadcast spawning." Males eject clouds of sperm into the water, and then females do the same with eggs. The sea creatures cross their fingers (or whatever the coral equivalent of that is) and hope for the best.

Scientists have observed this sort of thing before, but not with pillar coral, a rare type found in the western Atlantic and Caribbean that forms columns, or pillars. Marine biologist Kristen Marhaver, of the University of California, Merced, says that's because the researchers' timing was off. "For years, scientists were underwater about 30 minutes after the pillar coral spawned," she explains.

They were late in those expeditions because they were focusing on a different type of coral — elkhorn. As it turns out, elkhorn coral spawns just after the pillar coral does. Typically divers were still suiting up for the elkhorn spawning, Marhaver says, when the pillar coral was busy reproducing beneath their boat — and the divers would miss the pillar coral action completely. 

Three years ago, Marhaver and colleagues — with a group called Caribbean Research and Management of Biodiversity, on the island of Curacao — figured that out. Eventually they nailed down the pillar coral's mating moment.

The moment came "three days after the August full moon, 100 minutes after sundown," she says. So the next time they spawned, Marhaver was in the water waiting, and saw what looked like a cloud rising from the reef. npr

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