Near the Penghu Islands, off the west mainland of Taiwan, we and our partners from the Penghu Marine Biology Research Center are preparing to take tens of thousands of coral larvae by boat to the foundations of four offshore wind turbines at the Greater Changhua offshore wind farms. If the larvae succeed in settling on the foundations, this could be the start of a completely new approach to coral restoration.
For this proof-of-concept trial, surplus indigenous coral spawn will be collected from the shorelines of the Penghu Islands and incubated in a laboratory until they become viable coral larvae. After this, they can be taken to the wind turbine foundations, 35-60 km off the coast, and helped to settle there.
We’re working to create a net-positive biodiversity impact for all new renewable energy projects we commission from 2030. As one of our priority areas of work, we’re developing a suite of biodiversity-enhancing measures that the scientific community can stand behind.
The innovative ReCoral initiative complements this work by seeking to develop a completely new approach to coral restoration.
If the trial is successful and can be scaled up, our hope is that large numbers of larvae from subsequent generations of coral will be carried by ocean currents away from our offshore wind farms and settle on naturally occurring reefs, helping them to thrive.
The method we’re using has never been tried before. We can’t be sure it’ll be successful. But we’re committed to finding new ways of making a positive contribution to biodiversity.
Early tests and input from the scientific community suggest that the potential rewards of this project vastly outweigh the risks. And if the proof-of-concept trial is successful, we’ll look to scale up the method. We’ll make our findings public so that others can do the same.
"Naturally, given its novelty, the developers of this bold initiative have a number of significant challenges to tackle as they look to progress beyond their proof-of-concept trial towards a fully scaled-up deployment. It is encouraging to see, however, an industrial player collaborating with academics and environmental NGOs in an effort to secure the kind of ambitious and large-scale outcomes that are required”, says Ove Hoegh-Guldberg, Professor of Marine Studies at the University of Queensland in Brisbane, Australia
According to the World Wildlife Fund, coral reefs are among the most diverse and valuable ecosystems on the planet.
But our oceans are heating up because of climate change. Temperature increases can induce coral bleaching, which threatens the survival of coral reef ecosystems.
The International Union for Conservation of Nature has designated coral an endangered species.
Coral occurs naturally in such shallow waters that high surface temperatures can cause coral bleaching.
But in the deeper waters where offshore wind turbines are installed, a much more stable temperature is maintained, thanks to the circulation between the warmer water at the surface and the cooler water from below.
The foundations of offshore wind turbines provide a unique environment where corals can grow close enough to the surface to receive enough sunlight, but without being exposed to high temperatures. This limits the risk of coral bleaching.
Our approach to larvae sourcing is non-invasive. We only collect surplus coral egg bundles that wash up on shorelines, rather than removing anything from existing coral ecosystems.
Corals release billions of eggs – so many that they colour the water’s surface pink. Only some of these are fertilised and become larvae. The eggs we collect from shorelines are among those that wouldn’t otherwise survive.
Collecting them therefore has no impact on the corals that originally released them, nor on the propagation of coral species.
A marine biologist collects coral spawn at the shoreline using a plastic cup, entering the water at depths of up to 0.5 m to avoid collecting coral spawn that’s been washed over the sand, as this could affect its viability.
Collected coral spawn is then incubated in rearing containers in an onshore laboratory. On day five of incubation, we check how many eggs have created viable coral larvae.
At the wind turbine foundation, the coral larvae are released into custom-made seawater enclosures that are attached to the foundation with magnets. Neoprene sealing lines the enclosure, and a mesh cover allows the enclosures to be replenished with the surrounding seawater.
The larvae are left in the enclosures for four days, giving them time to attach themselves to the foundation. After this, we remove the mesh cage structures, exposing the coral to the surrounding water column and allowing them to grow.
For the seeding of coral larvae in the proof-of-concept trial, 1 m2 areas on four separate foundations will be used. The areas will be positioned 1 m below the lowest tide level. This will ensure that the corals are submerged by water, receive an adequate amount of light, and are accessible for deployment and monitoring purposes.
If the proof-of-concept trial on four wind turbines is successful, our next step is to develop a method where the concept can be applied to a larger area on another wind farm project.
Ultimately, the concept could be applied to offshore foundations of any kind in tropical waters around the world, boosting biodiversity.
Mature corals successfully thriving on offshore wind turbine foundations will release their own spawn, which could be carried by ocean currents to settle naturally elsewhere. This could boost genetic connectivity and support the restoration of existing coral reefs.
Larvae generated at offshore wind farm sites could also be captured, then transported to and released at naturally occurring reef locations.
In either case, restoring naturally occurring reefs would, in turn, support healthy stocks of fish and other reef species.
In the latest coral reef restoration guide released by the United Nations Environment Programme, larvae release is considered as ‘potentially one of the most scalable methods for coral reef restoration’.
We’ll share the techniques we develop and the lessons we learn with the broader coral conservation community and with other wind farm developers. Whether or not our pilot succeeds, our findings will be useful for future endeavours.
As ReCoral is an innovative scientific project, there’s an inherent risk that it won’t work. To address this, we’ve implemented a range of risk mitigation measures.
Collection of surplus coral spawn from the coastlines of the Penghu Islands and pilot test in an onshore laboratory and at a quayside test facility. Confirmation that coral larvae will attach to metal structures.
Detailed design and test of prototypes for the temporary habitats – mesh cage structures – in which coral larvae will be installed on the wind turbine foundations. Fabrication of these structures.
Net-cages are transported from Denmark to Taiwan. Coral spawn is collected, incubated at an onshore laboratory, and subsequently released onto four wind turbine foundations at the Changhua offshore wind farm site in the Taiwan Strait. Initial monitoring is conducted to determine whether coral have successfully settled.
