New approach paves the way for large-scale coral reef restoration

The troubling loss of coral reefs worldwide has prompted scientists and conservationists to assist the reefs’ recovery through active restoration approaches. A new innovation to sow coral larvae onto degraded reefs has the potential for effective large-scale reef restoration and minimise costly and time-consuming approaches. These are the findings of a new study led by an international team of researchers, among others Valérie Chamberland and Mark Vermeij from the UvA’s Institute for Biodiversity and Ecosystem Dynamics (IBED) based at Amsterdam Science Park. The results were recently published in the scientific journal Scientific Reports.

Close-up of a Seeding Unit with a boulder brain coral growing close to its centre. Photo: SECORE International / Valérie Chamberland

The aim of transplanting corals on degraded reefs is to increase coral cover and promote structural habitats. Until now, actual restoration has been done manually by divers who had to attach each coral, whether a fragment or a coral recruit settled on a substrate, individually. This is a costly and time-consuming approach. For instance, transplanting 10,000 individual corals on one hectare using common methods has until now required several hundred to a few thousand man-hours, whereas reef degradation occurs at a scale of hundreds and thousands of square kilometers.

‘If we want restoration to play a more meaningful role in coral reef conservation, we need to think in new ways. Our sowing approach is an important step towards reaching this goal since it will allow the handling of large numbers of corals in a very short space of time at significantly lower costs’, says Dr Dirk Petersen, project leader and executive director of SECORE International, a conservation organisation for the protection and restoration of coral reefs which employs a number of the researchers involved in the study.

Sowing coral larvae

In the new sowing approach, coral larvae are settled on specifically designed substrates that are self-stabilised and attach to the reef via natural processes. After a few weeks to months these so-called ‘Seeding Units’ (i.e., substrates together with initial coral polyps) are sown on the reef by simply wedging them in crevices rather than requiring manual attachment. ‘Sowing the same number of corals could be achieved in less than 50 man-hours, a time saving of over 90 per cent. Additionally, material costs could be reduced by up to one third, representing a substantial advance for future restoration work’, says SECORE’s research director Dr Margaret Miller.