Underwater Gardening: Restoring Coral Reefs

Underwater Gardening: Giving Coral Reefs a Second Chance

In this research update from October 2010, IOLR-NIO scientist Dr. Buki Rinkevich put forward a novel approach to repairing damaged reefs: growing new corals and then transplanting them onto deteriorating reef areas, in much the same way forests are felled and replanted.

Mid-water floating coral nursery in the Gulf of Eilat, Israel

Coral Gardening in Two Stages

Acting as a "coral gardener," Rinkevich devised a two-stage protocol:

Begin coral "seedlings" in the laboratory, then raise them in mid-water floating nurseries offshore.
Move the coral "saplings" grown in those nurseries onto the reef itself.

Why Protection Alone Is Not Enough

IOLR's working hypothesis is that conventional reef restoration, which centers on shielding reef areas from further harm, falls short of conservation goals. Reefs continue to degrade while we passively wait for coral growth to recover and reverse the decline. Stronger passive management does slow degradation and is essential, yet it is not sufficient. Global changes in water temperature and acidity, along with pollution, nutrient runoff, overfishing, coastal development, and overuse, are overwhelming and point to a grim future for coral reefs. Dr. Rinkevich holds that the future of reefs depends on "active" management: building large-scale nurseries and transplanting what they produce. Active restoration, combined with conventional passive reef management, is required to reverse reef degradation.

Testing the Approach

To put these theories to the test, in 2008 the first batch of several hundred nursery-farmed coral colonies was "planted" onto a bare reef area at Dekel Beach, Eilat. For each coral, a hole was drilled into the rock, a coral-bearing plastic pin was inserted, and the pin was secured with underwater epoxy glue. Two years on, the colonies had survived and thrived, with high growth and reproduction rates confirming their excellent health. The nursery-grown colonies became nursery grounds for coral fishes and for many crabs, bivalves, worms, and other invertebrates that live in close association with the corals. Researchers continue to monitor the coral gardens and watch for new recruitment of associated creatures at the site.

Experiments Around the Globe

In the decade after the first studies in Eilat, several projects in Southeast Asia (the Philippines, Thailand, and Singapore), Jamaica, and Zanzibar tested whether corals could feasibly be attached to and grown in floating nurseries. These studies set out to develop detailed protocols. The work has been supported by US-AID, the European Community, and the World Bank. As in Eilat, the coral nurseries in Southeast Asia, Jamaica, and Zanzibar are highly successful. At some sites researchers have already built nurseries and carried out transplantation, while at others they are still at the nursery stage. Most nurseries are mid-water, relying on floating devices of various kinds. Each nursery holds thousands of coral colonies. At every location the nursery is tailored to local conditions and to the local coral species that have been "planted."

Keeping It Practical

Steps have been taken to reduce the cost of raising and replanting coral colonies. Today a coral colony can be raised and replanted onto a reef for roughly US$1. IOLR's coral aquaculture technology has been shared with the scientific community, so reef restorers everywhere can draw on the know-how.

What Lies Ahead for Coral Reefs

Can coral gardening at massive scale reverse the worldwide decline of reefs? Can the "rainforests of the sea" — hotspots of biological diversity that sustain the oceanic food chain — be saved? Shifting how we see the vast oceans, from a boundless wild space to be hunted to a set of finite habitats to be protected and restored, will be a major "sea change." Yet thinking smaller may not be enough to save the coral reefs.

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Coral gardening pairs laboratory rearing with offshore nurseries and careful transplantation, so that damaged reefs can be rebuilt rather than simply left to recover on their own. The approach has been trialed in Eilat and adapted at sites across Southeast Asia, Jamaica, and Zanzibar, with each nursery tailored to local conditions and coral species.

Underwater Gardening