Vol. 3, No. 10

August 2007

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Photos by Bob Care/Florida Keys News Bureau

Dr. Alina Szmant collects coral spawn off Key Largo for a research project.

Every year, patrons of Florida Keys dive and snorkel shops play a guessing game. Locals and visitors alike try to guess the date and time of the annual coral spawn — sometimes nicknamed "sex on the reef" — on North America's only living coral barrier reef, which parallels the island chain.

Corals have evolved a method of reproduction called "broadcast spawning." The immobile animals send their eggs and sperm into the water in massive quantities. When egg and sperm unite, the resulting larval-stage "planula" swims to the surface to drift in the current and grow. After some time — two days to two months — the planula settles to the bottom where it grows into a polyp. The polyp grows into a coral head by asexual budding that creates new polyps.

Key to the successful creation of the next generation is corals in a given location broadcasting their eggs and sperm cells simultaneously. So the great mystery that has challenged researchers is: How do brainless, stationary, uncommunicative corals know exactly when to broadcast their spawn?

Thanks to the pioneering research of Dr. Alina Szmant of the University of North Carolina Wilmington, and ongoing studies by Dr. Margaret Miller of the National Oceanographic and Atmospheric Administration's National Marine Fisheries Service, the mystery surrounding the coral spawn gradually is being solved.

Szmant's observations have shown that Caribbean corals usually spawn around the mid to late August full moon.

A diver observes corals releasing eggs and sperm.

The generally accepted schedule is for branching corals (e.g., finger, staghorn and elkhorn corals) in the Florida Keys to spawn three to five days after the full moon, about two hours after sunset. Star and boulder corals spawn six to eight days after the August full moon, about three hours after sunset.

Guessing which night and at what time the corals will spawn is not an exact science, but professional researchers and amateur observers usually have a pretty good chance of seeing the action within a five-day span.

This year, the full moon is scheduled for Aug. 28. Therefore, divers and snorkelers visiting the Florida Keys National Marine Sanctuary should be able to catch a glimpse of one of nature's great mysteries in early September and a number of Keys dive shops offer up special evening excursions for voyeurs of the spectacle many have described as an "upside-down snowstorm."

Photo courtesy Key West Submarines

The Sirena offers subsea excursions in the southernmost city in the continental United States.

Want to explore the Florida Keys' underwater ecosystem without getting wet? Then take a cruise on the Sirena, an air-conditioned 40-passenger submarine that offers an intimate undersea view of the living coral reef that parallels the Keys and the creatures that inhabit it.

According to its operators, Key West Submarines, the 64-foot-long Sirena is the only fully submersible excursion submarine in the continental United States.

Passengers begin their adventure at the Westin Key West Marina, 273 Front St., where they board a Key West Submarines catamaran for their journey out to the Sirena. Upon arrival, they transfer to the sub and prepare for the dive.

While ocean currents and conditions determine the location and depth of the dive, most excursions descend to a depth of around 100 feet. Passengers can view the ocean realm through the Sirena's 30-inch diameter portholes, catching sight of vividly colored tropical fish and other creatures, a wide variety of corals and even a shipwreck.

When the submarine resurfaces, they reboard the catamaran for the journey back to Key West. The entire trip lasts approximately two hours — including 35 minutes of bottom time.

Cost of the excursion is $95 per passenger age 13 and up, and $75 per person for children age 4 to 12. For more information, visit www.keywestsub.com. For reservations, call (305) 295-3483.

A Lignum Vitae tree from Key West is on exhibit in Washington.

The Key West garden is among 22 U.S. institutions invited to participate in the exhibit, spearheaded by the United States Botanic Garden and the American Public Gardens Association. The Keys display stands outside the U.S. Botanic Garden Conservatory on the National Mall at the foot of the U.S. Capitol.

While touring the gardens in Washington D.C., visitors can listen to recorded information on each exhibit by calling (202) 730-9303 on a cellular telephone.

The 15-acre Key West Tropical Forest and Botanical Garden, located at 5210 College Road, includes 600-plus species of trees and plants — more than 60 of them endangered — a visitor and biodiversity center and a 1.5-acre butterfly habitat.

The free-admission garden is open daily. For hours and more information, visit www.keywestbotanicalgarden.org.

For more travel information on the Florida Keys:
www.fla-keys.com