Organised chaos might be the best phrase to describe this unique day. On 14 February, 2021, several citizen scientists were tasked with planting the mostly empty myriad of pots and planter boxes at the Coral Greenhouse at John Brewer Reef. The logistics of taking on this task meant that 20 divers descended 18 metres underwater with cement applicators, scrub brushes, and other equipment. Careful planning on land combined with adaptability in water meant that this goal was safely accomplished over two dives. So how exactly do you plant a coral?

Author giving briefing on the Coral Greenhouse to citizen scientists with help of a visual aid.

Just as with terrestrial gardening, proper sourcing of starters is important to give them the best chance of success in your garden bed. For the day’s gardening work, coral fragments were sourced from surrounding areas in hopes that transplantation in similar conditions will allow them to grow, albeit at a deeper depth than the nearby reef. Only “corals of opportunity” were used, those bits of coral that break off due to weather events and would otherwise die buried in the sand. Just like plants, many corals need access to sunlight, due to their symbiotic relationship with zooxanthellae algae. These little transplants will hopefully get a new lease on life within the raised beds of the Greenhouse.

Butterflyfish swimming by pots planted with corals in the Coral Greenhouse.

With the ever fluctuating environment underwater, planting is not as simple as digging up the ground and setting some coral inside. To keep coral fragments in the target areas, they need to be attached, just as they do naturally when beginning new colonies. To facilitate this process, we used concrete to fix the corals into holes within the planter boxes and pots. One planter box was sheltered with a grate to protect the vulnerable corals from grazers such as parrotfish, not unlike terrestrial gardens enclosed by wire mesh. While underwater gardening has some parallels with that above sea level, the most important is the start of new life.

Corals planted in an underwater garden bed, protected by a wire grate.

The team’s efforts mean that a previously empty garden now has over one hundred coral “sprouts” planted throughout. More corals will be planted in the future, but it was truly special to be part of this historical day. The Greenhouse looks more cheerful with the garden beds full, and even the statue figures seem to have more purpose looking down at the corals they’ve been entrusted. Time will tell how these corals of opportunity will fare, but this day was a day of collaboration, of camaraderie, of new beginnings and of hope.

Author planting a coral of opportunity at the base of a statue at the Museum of Underwater Art.