Spawning Research

Each year, about eight nights after the full moon in August or early September, corals at the Flower Gardens engage in mass spawning. Some species broadcast bundles containing both eggs and sperm. Other species release egg bundles and sperm separately. Some have described the event as looking like an upside down underwater snowstorm.

The millions of tiny sacks break open at the surface, where eggs from one colony are fertilized by sperm from a different colony (cross-fertilized). Drifting for several weeks at sea, few of the newly hatched coral planulae will survive. Those that do survive must settle in a place with a hard surface for attachment, clear sunlit water to support the symbiotic algae that will soon colonize the coral tissue, warm temperatures and sufficient water movement to provide plenty of food.

This amazing event was first documented at the banks in August 1991 when a group of sport divers noticed something very unusual happening at the Flower Gardens. Something they could only describe as smoking corals. The divers videotaped what was happening and reported their findings to scientists at Texas A&M University. The scientists knew what was going on, the corals were spawning.

Scientists knew, from past studies done on other reefs, that some corals spawn on specific lunar cycles. Because of this unique discovery, scientists believed they could predict when the coral at the Flower Gardens would again spawn. So a research team set for the banks in August of the following year and the coral spawned as predicted, seven to eight nights after the full moon. The event has happened every year since.

The annual mass spawning is a truly awesome demonstration of nature's persistence that inspires even the most well-traveled divers.

Spawning Research
Scientists wanted to know how this spawning compared to spawning at other Caribbean reefs. So in 1995 "Project Reefspawn" was created to compare the Florida Keys, Roatan, Bahamas, Cozumel, and the Flower Gardens. Spawning was evident at the other coral reefs, but the Flower Gardens was still the big event, more was seen there than elsewhere. Divers recorded their observations at designated monitoring sites each night at the four locations. With the Flower Gardens as a central location for the expedition, researchers communicated by cellular phones to compare the spawning, the water and atmospheric conditions.

Coral colonies vary in shape and form. Coral colonies enlarge through asexual reproduction. This form of reproduction results in genetically identical polyps throughout the colony. There are three types of asexual reproduction: intra-tentacular budding, extra-tentacular budding, and fragmentation. Intra-tentacular budding occurs when a polyp simply divides itself into two complete polyps (i.e. it occurs inside the tentacles). Extra-tentacular budding occurs when new polyps "sprout" up between the existing polyps (i.e. it occurs outside the tentacles). Fragmentation occurs when a chunk of a coral colony is broken off for some reason, such as a hurricane or a boat anchor hit. If the fragment lands with the polyp side up, it can reattach itself to the sea bottom and continue to grow through budding, thus creating a new colony.

Colonies also enlarge by two sexual reproduction processes. One form of sexual reproduction is known as brooding. Another form is known as broadcasting.

The reefs have the capacity to repopulate from within as a result of local coral spawning. They don't need to depend on larvae from other reefs hundreds of miles to the south. Active spawning may be one of the reasons why the Flower Garden Banks are among the healthiest reefs in the Gulf of Mexico and possibly the world.

Scientists studying coral spawning use Satellites to track larvae. Once the egg bundles appear at the surface, a satellite-track buoy, provided by the U.S. Department of the Interior, is deployed to drift with the spawn slick. Signals are released daily to tell the probable location of the drifting larvae.

Because of the health of the reefs and the predictability of the mass coral spawning, the Flower Garden Banks have become an ideal area for a new type of research. This research involves taking samples of the bundles and sperm released from the corals, growing young corals in a laboratory setting, then taking them back out to the reefs to if they will grow. Scientists are hoping to use this technique to repopulate coral reefs that have been damaged by human activities.

In order to harvest the samples necessary to conduct this research, divers use handcrafted butterfly nets to collect small egg bundles as they are released from the corals. Sometimes, divers wait patiently for several minutes at one coral head, to catch the bundles as soon as they are released. The samples are then placed into plastic bags and taken to the surface, where they are separated and delivered to the laboratory.

In the laboratory, under controlled conditions, scientists place the larvae on artificial substrates and allow them to grow. Once grown, the adult coral animals are returned to the ocean, back to the coral reef. While it is still too early to tell, if this research is successful it could become a valuable tool in coral reef management. It could not only speed up the process of rejuvenating damaged reefs; it could also prevent the mutilation of one reef in order to repair another