Successful initiation of a larval rearing program
The numbers are impressive: Approximately four million larvae of grooved brain corals (Diploria labyrinthiformis) were produced and 700 settlement substrates carrying coral settlers were outplanted, when FUNDEMAR ran its first coral reproduction and restoration event in May 2019.
After the spawn collection comes fertilization work, which was done in FUNDEMAR’s new wet lab. The team mixed eggs and sperm of 27 grooved brain coral colonies (top and bottom row) and got approximately 4 million coral embryos, each of them genetically unique. (Paul Selvaggio)
A win-win situation
With this joint work, FUNDEMAR reached a new milestone on its way to large-scale reef restoration in the Dominican Republic. In the past few years, FUNDEMAR director Rita Sellares and her team have spared no effort to learn larval propagation methods, set up a new wet lab in Bayahibe, and document the local spawning times of seven coral species so that a spawning prediction calendar could be created and updated each year.
“We were inspired by guest scientist Johanna Calle, who had run a small larval propagation pilot project using assisted fertilization and coral culturing techniques in Bayahibe in summer 2015 and 2016”, Rita Sellares says. “Her success was the reason for us to decide that we wanted to upscale the production of coral sexual recruits.”
The team attended SECORE’s joint coral reproduction and restoration workshops in Curaçao (CARMABI Marine Research Station) and Mexico (Coralium lab at UNAM) and officially joined SECORE’s network as a restoration partner in August 2018. As such, SECORE not only provided a coral larval rearing pool and settlement substrates for this year’s spawning events, but a team of four also went to the Dominican Republic to help with the pool set-up, the gamete collection, and the lab work. “For us, this collaboration with FUNDEMAR is a perfect win-win situation. Rita and her team know the area very well and have built a vast network of partners and volunteers. We have the opportunity to share our techniques with them and grow the program in the country, and it allows us to test our new technologies and their ability to be adapted to a new location. It was really exciting to deploy one of our new larval rearing pools off the coast of Bayahibe,” says SECORE Operations Manager Aric Bickel.
The larval rearing pool provided by SECORE (top) was filled with tetrapods and some of FUNDEMAR’s hand-made settlement substrates that had been conditioned in the ocean for almost a year. Right before coral spawning divers collected the cookie-shaped substrates from the ocean floor and brought them back to the surface. All of this work was done in close cooperation and with great team spirit (bottom row). (Paul Selvaggio)
Four million coral embryos
The pool, which proved to be more stable and easier to deploy than its predecessor, was filled with settlement substrates and several hundred thousand coral embryos. “This amount of coral offspring only represented a small share of the total number of coral larvae that we reproduced”, Rita Sellares reports. “Of the 4 million embryos that we produced, we ended up putting 750,000 embryos in the pool. The rest were reared in our wet lab; we released the biggest share of these embryos onto the reef in hopes that they would find a place to settle there as well.”
One of the best ways to check coral settlement rates is shining a blue light on the substrates. All settled coral larvae will start fluorescing then (right), which helps to spot the tiny coral babies. And that’s exactly what FUNDEMAR’s Rita Sellares and colleagues Juan Roberto Adrien (Yonci) and Alido Luis Báez did in the lab (left) and in the pool (middle). They counted an average number of 14 settlers per substrate. (Paul Selvaggio)
This huge number of 4 million coral embryos were produced from the egg and sperm bundles collected from 27 grooved brain coral colonies that had spawned exactly as FUNDEMAR had predicted – on the 28th and 29th of May. Twelve days later, when the coral larvae in the pool had finally settled on the substrates, Rita Sellares and her colleagues outplanted the substrates onto the Sombrero Reef off the coast of Bayahibe. Now the team and all partners keep their fingers crossed for a maximal survival of the baby corals. Assuming that only one coral settler per substrate will grow into a colony, we hope that in the near future hundreds of small, genetically unique grooved brain corals will be discovered in the waters of Bayahibe.
Almost two weeks after coral spawning, Rita Sellares and her team outplanted 700 settlement substrates, each carrying baby corals. While the self-attaching tetrapods were placed into little nooks and crevices on the reef, the cookie-shaped substrates were fixed with nails. (Paul Selvaggio)
While the SECORE team returned to Curaçao, Miami, and Mexico after most of the field and lab work was finished, Rita Sellares and her team are going to continue their spawning work throughout the summer. FUNDEMAR’s spawning calendar for the Dominican Republic also lists species such as staghorn coral (Acropora cervicornis), elkhorn coral (Acropora palmata), boulder brain coral (Colpophyllia natans), lobed star coral (Orbicella annularis) and mountainous star coral (Orbicella faveolata). So, it is hopefully going to be a busy and successful spawning season in the Dominican Republic.
FUNDEMAR’s coral restoration work is supported by several international organizations and allies, amongst them: The Nature Conservancy in the Caribbean, USAID, USFWS, the German Embassy in the Dominican Republic, CORALIUM, Dressel Divers and other partners and volunteers. SECORE’s support of the program comes through the Global Coral Restoration Program, funded by the California Academy of Sciences and the Nature Conservancy. Our special thanks also go to our corporate and Zoo & Aquarium partners.
FUNDEMAR started its reef restoration work in 2011 with a coral gardening and fragment transplanting program. This is one of its 8 staghorn coral (Acropora cervicornis) gardens. All of them are managed in close cooperation with local dive shops and resorts and hold more than 3 kilometers of coral tissue all together. (Paul Selvaggio)
Text: Sina Löschke/Aric Bickel