Status: 04/12/2023 06:32 a.m
Climate change has destroyed much of the coral reef off the Florida coast. Scientists are trying to save the reef by growing corals and transplanting them by hand.
Again and again the pointed end of her hammer hits the dead rock of the reef off the Florida coast. At a depth of just three meters, Roxane Boonstra is trying to create an algae-free space for new corals to settle in. She needs three circular contact points the size of a biscuit to attach a so-called staghorn coral with the shape of an antler to the sandy rock.
Roxane equips the ends with a small ball of a special adhesive paste that is reminiscent of play dough. After a few seconds the coral is stuck. “Our biggest opponent is the current,” says the marine biologist. “Some days we are powerless against them.”
Most of the transplanted corals survived
She and her team from the Coral Restoration Foundation have already repeated this process 200,000 times. According to recent studies, 75 percent of the corals transplanted in this way survived. A glimmer of hope, nothing more: “Every day another part of the reef dies. Every day the sea continues to warm up. Every day there are new dangers from climate change.”
According to the United Nations, less than one percent of the world’s oceans consist of coral reefs – yet 4,000 species of fish and 40 percent of all marine life depend on them at some point in their lives. Coral reefs are used for spawning, hatching and raising offspring – or for foraging and protection from predators. “They are something like the rainforest of the world’s oceans,” says Boonstra, “incredibly rich in species and extremely important”.
Seabed is like a graveyard
The reef off the Florida coast is as long as the Autobahn from Hamburg to Berlin – several hundred kilometers. The third largest barrier reef in the world is protected by the Florida Keys National Marine Sanctuary – home to more than 80 species of coral. No hunting or fishing is permitted within the sanctuary. Nevertheless, in some places more than 90 percent of the corals that originally lived here have died.
The main cause is climate change – in addition to shipping, fishing and pollution from plastic waste. The sight of the dead reef is desolate: hardly any fish, hardly any colors. The seabed looks like a graveyard, says Boonstra. Full of skeletons of dead coral.
slow growth
To bring the reef back to life, Boonstra and her team built the world’s largest underwater coral nursery near the shore. 30,000 finger-sized pieces of coral sway in the ocean currents on the branches of 500 plastic rods reminiscent of Christmas trees. This accelerates their slow growth of around two centimeters per year.
Scientists at the Coral Restoration Foundation in Key Largo have discovered how growth can be accelerated: If you break the coral into pieces of two to five centimeters, it will double in size over a period of a few months.
“Don’t have too high expectations”
Once they are big enough, they are cut off and replanted on the reef. Although the better expression would be: corals are not plants, but small animals, more precisely: polyps. An area the size of 64 soccer fields is to be revived in the next 20 years. The most common question is whether that can work, says Boonstra. She is optimistic.
Nevertheless, one should not have too high expectations. “We can’t restore the reef to how it was 100 years ago,” she says. “But the hope is that we can stabilize it enough that it can eventually heal itself.” The “Mission Iconic Reefs” project is currently underway off the Florida Keys. The aim of the project is the reforestation of seven coral reefs. The afforestation is to be carried out in two phases.
The first phase lasts ten years and focuses on fast-growing elk and staghorn corals. Only in the second phase will the slower growing coral species follow.