Field Update: Restoring Coral Reefs

This is the second year Jennie has joined SECORE International on the Caribbean coast of Mexico. Since 2012, this team has traveled to this area to join in catching the annual spawning of a critically endangered coral species, Elkhorn coral (Acropora palmata). In the week following the hottest full moon of the year, Elkhorn coral colonies will spawn at the same time, presenting a unique opportunity for scientists to aid in the reefs' reproduction.

The reefs, Bocana Chica, Limones and Punta Venado, are all located off the coast of the Riviera Maya. When the corals spawn, divers quickly collect the gamete bundles of sperm and egg in plastic containers as they're released into the water and snorkelers carefully swim them to boats nearby to begin the fertilization process.

Then the real work begins. The teams expediently make their way back to their respective labs at the National Autonomous University of Mexico (UNAM) and Xcaret Park. There, fertilization continues, and the eggs are gently cleaned to provide a sterile environment where the embryos can develop free from predation and environmental contaminants. Several issues including a lack of genetic diversity, the spread of coral colonies and poor water quality make successful reproduction from these spawning events a near impossibility without assistance from researchers.

As the coral embryos develop over several days, they become larvae, eventually swimming downward looking for a place to permanently attach and grow. In preparation for spawning, specialized thousands of tiles were fabricated and placed off-shore for several weeks to attain a natural biofilm and algae that provide chemical cues to the larvae, indicating that the tiles are an appropriate substrate to settle upon. The newly settled larvae are allowed to establish themselves and grow on the tiles before being placed back onto the reef for their continued growth.

This year, researchers worked to refine the design of many apparatuses used throughout this process. SECORE researchers work to develop inexpensive coral restoration techniques for use in remote locations. Design improvements on last year's small-scale larvae rearing vessels included making the entire apparatus floating, rather than being supported by a stand. This allowed it to rise and fall with changing water levels while maintaining uniform water exchange and motion for the developing larvae. This modification proved highly successful. Additional experiments and apparatuses were also constructed to test the feasibility of replicating these techniques on a much larger scale.

The full process, from the spawn to the out-planting of the larvae covered tiles, takes a number of weeks. This work is critically important for the continued growth of these reef-building corals which sustain many parts of ocean life, such as providing habitat for animals and storm protection for shorelines. As corals are impacted by many environmental and human factors, the work done by the SECORE team is critical to increasing the biodiversity of these corals to make the process as efficient and inexpensive as possible will hopefully allow the these reefs the opportunity to thrive once again!