Coral nurseries floating in Grand Cayman’s coastal waters have performed better than expected, according to reports from dive groups.

Sea of Change Foundation adviser Jerry Beaty said the nurseries have propagated 700 feet of coral since they were set up in April 2016. The growth has been double that of initial estimates.

“They are doing better than any of us expected. We wouldn’t have put our hopes up quite this high,” Mr. Beaty said.

“To get that much growth that quickly was pretty amazing. When it took off the way it did, we were very cautious.”

Sea of Change, a U.S.-based organization, donated money and coordinated training through the Coral Restoration Foundation to set up Grand Cayman’s four coral nurseries, which primarily grow staghorn coral.

The Grand Cayman nurseries have been managed by local divers from Ocean Frontiers, Sunset House, Cayman Eco Divers and Divetech. Additional assistance has been offered by Red Sail Sports.

While the ultimate goal of the nurseries is to create self-sustaining organisms that can thrive in a natural reef environment, the fragments currently depend on divers to control algae and regulate growth patterns.

Their overall success will depend on the suitability of the reef ecosystem, which will require healthy populations of species like parrotfish to control algae growth.

While Mr. Beaty described Cayman’s reefs as relatively strong compared to many other regions, he pointed out that threats still exist from bleaching, provoked by higher water temperatures, and destruction caused by ships, anchors and overfishing.

Aaron Hunt and Brittany Balli from Cayman Eco Divers work on a Grand Cayman coral nursery. – Photo: Charlotte Roslev

Department of Environment senior research officer John Bothwell said government initially approached nurseries with caution, in part to avoid fragmenting coral without the proper research to ensure success. The department first approved a test site operated by the Central Caribbean Marine Institute in Little Cayman. That site has been used to inform efforts on the main island.

“That has paid off in that all the reports we are getting have been positive,” Mr. Bothwell said.

Cayman Eco Divers co-founder Aaron Hunt said around 90 percent of the coral fragments have thrived at the Waldo Reef site he helps manage.

He said the Coral Restoration Foundation traveled to the islands last April and taught divers how to harvest, hang and organize coral fragments on PVC trees. The foundation is expected to travel to the island again this year to guide outplanting on the reef.

Mr. Hunt attributed part of the success in Grand Cayman to careful site selection. The nurseries have been hung in deeper waters to protect them from high temperatures and predatory animals.

“The way we have the coral nurseries set up is a little out of the normal character for nursery sites elsewhere in the world, because they are suspended in mid-water. They’re protected from predatory organisms and just deep enough to not be prone to temperature fluctuations in shallower areas,” Mr. Hunt said.

Divetech’s Jo Mikutowicz said the coral at the Lighthouse Point nursery has grown so well that divers there had to make more fragments and add an additional PVC tree. Otherwise, the growth would be at risk of dragging down and attracting predators like bristle worms and snails.

Her goal is to continue propagating coral until the organisms are ready to be taken out to the reef and planted in a natural ocean environment.

“The shallows used to be lined with antler coral, so we’re trying to replenish areas damaged due to weather or anchors,” she said.

Mr. Bothwell added that while successful coral nurseries are a step in the right direction, they are only one part of the solution.

“Our reefs are still relatively healthy, but that is in the context of reefs in the Caribbean and around the world being under a lot of stress. We cannot get over-confident about our reefs and relax. We must move forward with anything possible to make them better,” he said.

One limitation of coral nurseries is that they are better suited for production of certain coral species over others, Mr. Bothwell explained. While staghorn coral, for example, naturally propagates through fragmentation, not all coral species grow in the same way.

“These coral nurseries are really great but they are fairly focused on one species of coral. As hard as the groups are working, there is only so much coral they will be able to grow and outplant. They are only one part of what we need to do,” he said.

Mr. Bothwell noted that divers will not be able to keep the reefs fully protected without the support of government. He said a marine parks enhancement proposal has been put before the Cabinet for approval. It seeks to enhance and expand marine protected areas, as well as control overfishing.

While Cayman alone cannot control global forces like climate change, he said, the islands can take their own steps to promote healthy waters and encourage robust marine populations. He hopes the proposal, once approved, will update environmental regulations and strengthen reef protections.

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