giving coral reefs a future

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Hundreds of French Grunts (Haemulon flavolineatum) patrol the Cuevones Reef north of Cancun, Mexico, where sexually reproduced elkhorn corals were outplanted in 2015 to restore a ship grounding site. (Sandra Mendoza)

When you look at the underwater photos, which SECORE Restoration Technician Sandra Mendoza has taken on her latest trip to the Cuevones Reef north of Cancún, you would not believe that 22 years ago a cruise ship ran aground here, severely damaging the reef structure and reducing coral cover from 14% to 1% within an area of 480 square meters. Most of the colonies affected were the Elkhorn coral, Acropora palmata, a protected species. Today, Sandra’s pictures don’t show any traces of destruction. Instead, flocks of yellow reef fish are dancing above a thick carpet of sea fans, anemones, soft and hard corals, especially Acropora palmata, making this reef site a diver’s dream come true.

Only an eagle eye may spot the small, yellow tags, which mark some of the elkhorn coral colonies (Acropora palmata) growing on the reef. These elkhorn corals are reef-building corals and were among the very first that have been produced by scientists using larval propagation techniques. “When the National Fisheries Institute asked us, in 2010, to participate in this ship grounding restoration project we had already figured out how to collect coral spawn, produce genetically unique coral offspring and keep those coral babies alive,” says coral biologist Dr. Anastazia (Ania) Banaszak, lead scientist of the Coralium Lab at the National Autonomous University of Mexico (UNAM) in Puerto Morelos.

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Yellow number tags mark the colonies that were produced and outplanted by the Mexican scientists. When they were transplanted on the reef, they were 10 to 15 centimeters in diameter. Now, after five years on the reef, they have tripled their size. (Sandra Mendoza)

In the beginning, it was learning by doing

Some steps of the larval propagation process that are now common knowledge among restoration practitioners, the team had to learn by using the trial and error principle. “To enhance larval settlement, we bought small kitchen tiles in our local Home Depot. The elkhorn coral larvae refused to settle on those tiles. They preferred handmade concrete substrates. But the offspring of mountainous star corals, we worked with, just loved them”, coral mom Ania Banaszak says.  

For the first couple of years, the scientists kept the coral babies in aquaria at the Xcaret Ecopark Aquarium in Playa del Carmen. It was the only facility in the area that had a perfectly working sea-water flow-through system. Sandra would go every week, sometimes twice a week, to clean the tiles and take care of the tiny coral babies, which are easily overgrown by algae. Later on, the young Elkhorn corals were moved to a mid-water nursery on the reefs near Puerto Morelos. From there, they were transferred to the damaged reef site in 2015.

 “When we outplanted our elkhorn coral colonies, they had a maximum size of 10 to 15 centimeters in diameter. Now the colonies measure at least 40 centimeters and all of them but one look really healthy and strong”, says Sandra Mendoza.

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The conditions on Cuevones Reef are perfect for Elkhorn corals. The outplanted colonies – left, photo from 2015, right, photo from 2019 – grew much better than Elkhorn coral colonies which were kept in a nursery at the same time. (Melina Soto / Sandra Mendoza)

To increase the coral coverage on the grounding site even further, project partners from the Fisheries Institute added fragments of Elkhorn and Staghorn (Acropora cervicornis) corals to the damaged reef. Hence, not all coral colonies depicted in the photos are sexually reproduced and therefore genetically unique. However, the scientists hope that those fragmented Elkhorn colonies are able to reproduce sexually with their genetically unique neighbors and produce self-sustaining populations – a step all coral reef restoration practitioners are aiming for.

A new partnership

“The initial results of this restoration project at Cuevones Reef were also the starting point of our collaboration with SECORE”, Ania Banaszak says. When she gave a talk about her larval propagation work at the ICRS conference in 2012, Dirk Petersen SECORE Founder and Executive Director, sat in the audience. Afterward, both scientists talked and shared ideas about larval propagation techniques. One year later, in 2013, UNAM and SECORE ran their first of many joint coral reproduction and restoration workshops in Puerto Morelos. Since 2015, they have been using SECORE’s concrete tetrapods that, fortunately, both Elkhorn and Mountainous Star coral larvae liked.

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Dr. Anastazia Banaszak (left), head of the Coralium Lab and SECORE’s local lead for restoration and conservation efforts along the Mexican Caribbean. She is supported by SECORE’s Restoration Technician Sandra Mendoza (middle). The photo on the right shows the tetrapods, which were used for coral settlement in 2015. (Sina Löschke, UNAM, Paul Selvaggio)

Since then, both partners have taught dozens of students and restoration practitioners and have outplanted an abundance of sexually reproduced coral settlers onto the reefs along the Mexican Caribbean, working with five different species. Sandra’s colorful pictures of the Cuevones Reef prove that reef restoration definitely helps damaged reefs to recover. But it needs to be done as a joint effort, using all the tools and different approaches restoration pioneers have developed.

The restoration at Cuevones Reef was funded by the National Commission for the Knowledge and Use of Biodiversity (CONABIO) and was accomplished by Anastazia Banaszak and her team in cooperation with:

• Centro Regional de Investigación Pesquera Puerto Morelos, INAPESCA
• Parque Nacional Costa Occidental de Isla Mujeres, Punta Cancún y Punta Nizuc, CONANP
• ECOSUR-Unidad Chetumal
• Parque eco-arqueológico XCARET.
• Unidad Académica de Sistemas Arrecifales Puerto Morelos, ICMyL, UNAM

Sina Löschke