Sex On The Reef!

Only once a year, on America's only living reef does the coral 'get it on!
Sex On The Reef!
Key West, FL
It happens every summer on a few steamy, sultry nights under a waning moon...then, when everything is just right, the reef explodes in a frenzy. It's an annual subsea love-making ritual known as "Sex on the Reef." Branching corals, boulder corals, hard corals and soft synchronize with a fading moon and engage in what is thought to be their only sexual act of the year, spewing millions of luminous eggs and sperm toward the night sea's surface. And it's driven by the wind!

Spawning is sexual reproduction-the mixing of genetic factors through the meeting of an egg and sperm. But coral primarily reproduces itself asexually, where identical coral organisms or polyps are formed through budding...but is it fun, you may ask? And what's all this have to do with the wind? Well, wind has been around at least as long as coral and the delicate branching corals have adapted to their vulnerability by using "storm destruction" as a means to increase their numbers. It's called fragmentation...pieces of coral structure are broken from the entire colony. If a fragment lands on solid bottom, it may fuse right there and continue to grow through budding. There are some real advantages to this means of asexual reproduction. The new colonies help to expand the reef as a whole, covering otherwise unrecruited surfaces with living coral.

Along the highway, dive shops begin displaying signs advertising night dives...the experienced eye knows that it's time for the coral to spawn. Nightime dives are an exciting adventure under any circumstances, but a visit to the Florida Keys National Marine Sanctuary in late August is "orgy time!" Divers are treated to an undersea orgy, described by many as an upside-down snowstorm as the water fills with tiny pearl-like eggs and smoky sperm. This rare spectacle, however, was unknown to most until the 1980's. It only happens once a year, for a couple of nights and is thought to be closely associated with the lunar cycle.

At first, it seemed that most of the action was happening eight days after the full moon in August. Further observation showed, however, that the time frame was different for different types of corals. Branching corals like elkhorn and staghorn tend to spawn more closely with the full moon, while the star corals wait until eight days following the full moon. More recently, it's been discovered that these time frames may vary according to your latitude. As you travel south, the event seems to spread out over a longer period of time and you may not have to wait the full eight days. It is clear that the moon influences the reproduction, it is not clear whether there are other triggers?

Regardless, coral spawning is an amazing thing to observe and it is an event of orgasmic proportion...sort of love-making a la Coral! If you don't usually night dive, you may not recognize the place. The usual smooth green and brown surfaces of the stony corals will be alive with the feathery feeding tentacles and many of the reef fish that forage in the daytime will be absent and others are out feeding. Oftentimes, other critters will get turned on as well and spawn as well. There is a good chance you will witness sponges, brittle stars, gorgonians and even Christmas tree worms spawn at the same time...Yikes! This will draw bigger fish hoping to feed on the smaller fish and an entire food chain may be observed in a microcosm.

The spawn takes place on Keys patch reefs from 3 to 5 feet deep as well as on reefs that are 50 to 60 feet deep and scientists take the natural celebration very seriously as it serves as a step toward building new coral reefs. The whole process, however, only takes a half an hour...but that sure beats "ten minutes" any day or night! This year, researchers from the University of North Carolina-Wilmington plan an ambitious field experiment. The experiment involves tracking a spawn slick to see how far the larvae travel before they begin to settle. Last summer, the same group enjoyed modest success with the elkhorn coral seeding work and are optimistic about their chances this season. It is hoped that the coral spawn will breed infant corals to generate new reef habitats. The scientists plan to collect spawn from elkhorn coral Aug. 3-6 and from star coral Sept. 3-5.

The University of North Carolina researchers will also be working hand in hand with representatives of The National Oceanographic and Atmospheric Administration's Southeast Fisheries Center and the Florida Keys National Marine Sanctuary to gather coral egg and sperm bundles, nurse the resulting offspring and place them with "adoptive" live-rock families to replenish area reefs. It's a delicate and difficult process, but thanks to the insightful knowledge of the many dedicated researchers, scientists and hundreds of divers who share information they've observed, the mysteries of this rare occurrence in the under sea world are slowly unraveling. Even the prediction of this grand occasion has become more of an an exact science...the beginning of new life in the ocean. If left alone, nature will always find a way to " keep the love alive" so that this coral and future generations of it will survive long enough to live a full life and in its existence, allow other creatures to marvel in its presence!

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