Robots race to save dying coral reefs

Taryn Foster thinks Australia’s dying coral reefs can still be saved if it can speed up rescue efforts. For years, biologists like her have been lending a helping hand to reefs struggling with rising temperatures and ocean acidity: they have collected coral fragments and cut them apart to propagate and grow them in nurseries on land; they crossed species to increase their heat resistance; they experimented with probiotics as a defense against deadly diseases.

But even replanting thousands of these healthy and rejuvenated corals on damaged reefs won’t be enough to save entire ecosystems, Foster says. “We need some way to deploy corals at scale.” Sounds like work for some robots.

In a healthy ocean, individual corals, called polyps, build their skeleton by extracting calcium carbonate from sea water. Then they merge with corals of the same genetic composition, forming huge colonies – coral reefs. But as the ocean absorbs more carbon dioxide from the atmosphere, the water becomes more acidic, making it difficult for polyps to build their skeletons or keep them from dissolving. Acidification is holding back the growth of reefs, and as global ocean temperatures rise, corals struggle to survive.

On the Great Barrier Reef, for example, coral growth has slowed in recent decades, in part because corals crowd out the tiny algae that live inside their tissues and provide them with nutrients during heat waves, causing them to bleach. Bleached corals are not dead, but are more at risk of starvation and disease, and the loss of coral reefs has a devastating effect on the thousands of fish, crabs and other marine life that rely on them for shelter and food.

Growing new corals in a nursery and manually grafting them onto existing reefs is a labor intensive, expensive and slow process. Corals are slow growing by nature: it takes them three to ten years, depending on the species, to build an adult-sized skeleton. With his Coral Maker company, Foster is trying to speed up this process. Before researching coral reefs and climate change, Foster worked in the family stone business. She now uses her family’s dry-casting machines to produce limestone molds that resemble natural coral skeletons – the plan is to provide young corals with a suitable base from which they can grow faster.

The first prototype of the Coral Maker skeleton is domed and has six stubs where live coral fragments can be placed. The design of the skeleton is inspired by nature: many species, such as brain corals, grow in a dome shape, while branching or plate corals grow upwards from a solid base. But there are also problems with domed skeletons, says Foster. “They’re not as easy to make as something with a flat surface, they’re not as easy to palletize, they’re not as easy to stick on.” That’s why Foster continues to work on the design so that the stone machinery will soon be able to produce up to 10,000 pieces a day for just a few dollars. This process can then be replicated in other factories.