Coral Spawning 2005

Flower Garden Banks 

"The Texas Caribbean"

The timing of this years trip was set to coincide with the annual coral spawning event in the Gulf of Mexico which occurs each August eight days after the full moon. Eric Borneman lead a team of aquarist "helpers" to collect egg bundles released by the corals and maintain them in a temporary holding tank while the ship was at sea. The following information provides an introduction to this project, outlines the process, and offers insight into this next generation method of coral collection.

The concept began as a research project initiated at the Rotterdam Zoo in 2001. It was designed to examine coral reproduction and breeding techniques in closed systems. Dr. Dirk Petersen and his colleagues shared their results with other public aquariums and institutions. In the 3 years that followed they formed an international network known as SECORE (SExual COral REproduction). SECORE held its first workshop in June 2005 hosted by the Rotterdam Zoo, the Netherlands. It was here that Eric Borneman worked out the techniques for egg collection.

Dive team members included Tim McRae, Eric Borneman, John Dawe, and Michael Janes.

During a mass spawning event eggs and sperm are released into the open water column. It is here where the eggs are fertilized then set adrift in the currents with the potential to form young coral larvae. The eggs are collected by funnel shaped nets. As the net narrows toward the top a small catch vessel is attached. As the eggs are released by coral polyps they drift upwards into the catch vessel.

The plan was to transplant the collected eggs with seawater held in the catch vessels into large ice chest coolers kept on the upper deck of the boat. The two coolers contained clean seawater gathered earlier in the day and used battery powered air pumps to aerate the water.

The seawater was constantly stirred to keep the eggs from coalescing along the sides of the cooler and to ensure their chances for fertilization.

During the next 30 hours the eggs were diligently cared for and checked for cellular multiplication as a sign that the eggs would develop into viable coral larvae. A stereomicroscope was used on board the boat to monitor the progress of the eggs. As the cells multiplied the initially spherical eggs took on an obvious change in shape that appeared lobed like.

After 20 hours the coral larvae were ready to settle out of the water onto a hard surface. Ceramic tiles were placed on the bottom of the ice chest coolers. These tiles had the appropriate surface features, texture, and biofilm to act as a functional substrate for the corals to settle onto.

Once the boat was back at dock and the ice chests with young corals safe loaded into vehicles they were taken to Eric's Houston area lab. The tiles were transferred to grow out tanks. They were monitored for development and survival rates were calculated. 

This process has been successfully preformed in the research arena and similar techniques are now being used in commercial coral farming operations. This noninvasive technique is an opportunity to rescue coral eggs from the rapid decay they would otherwise experience in the ocean as only a few of the eggs are intended to survive fertilization, settlement, and eventually develop into mature coral colonies. In the years to come it is highly likely a large portion of the live corals sold in the aquarium trade could be grown from collected eggs!