To Create a Coral From Scratch…

…you must first invent the universe.  Fortunately, that’s already been taken care of.  Now we can make baby corals by forcing their parents to reproduce with each other.  If it sounds barbaric, don’t worry, we’re simply helping nature along.  Here’s the breakdown:

Corals are sedentary.  Once they find a good spot on the ocean floor, they tend to stay there forever.  This makes reproduction a real challenge.  How are two adults supposed to ‘get together?’  The answer is simple: use the currents to your advantage.  Release enough gametes into the water column so that your spawn is bound to meet up with someone else’s. 

This strategy requires two important steps.  First, corals need to invest their reproductive energies into creating vast quantities of gametes.  Second, all the corals in an area need to spawn at the same time.  How they manage to do this has yet to be completely figured out, but it depends on several environmental cues.  We can tell you that an Acropora palmata in the Caribbean will likely spawn approximately 2 hours after sunset, 3-7 days after the full moon in August.  In other words, possibly tonight!

Since we have the potential spawning time frame pinned down, we can anticipate the event, and intervene before gametes from different corals have a chance to mingle.  We do this by placing large nets over the colonies.  When eggs and sperm are released (Acropora palmata is hermaphroditic, so it releases both simultaneously in small bundles), they float up and get caught in an inverted cup at the tip of the net.  Back in the lab, we can separate sperm from egg, and make our own crosses between distinct parents.  That way, we have control over the genetic composition of the larvae that result from fertilization. 

Being able to conduct controlled crosses opens up a whole world of research into the genetic basis of a range of important characteristic for endangered corals.  Which genes are being targeted by natural selection?  How important is paternity in dictating dispersal potential?  How quickly can corals adapt? 

When we find that certain crosses perform better than others, we can prioritize which individual colonies in a given area should be targeted for conservation.  When possible, we even plant our coral babies back out onto the reef, and past experience has proven that at least some of them survive.  When you consider how many millions of larvae die naturally, having just one or two juveniles last for a year on the reef is a huge success. 

So, every evening, we don our diving gear and our nets and our flashlights and head back into the ocean, hoping that tonight will be the night.  Wish us luck!

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