A new artificial reef made of 3D-printed clay tiles off Mindanao, Philippines, is successfully attracting colorful marine life, demonstrating the potential of innovative reef restoration techniques by the Swiss start-up Rrreefs. Co-founder Ulrike Pfreundt aims to combat coral destruction exacerbated by climate change. While methods like assisted evolution may enhance coral resilience, scientists remain cautious about the overarching threats posed by rising ocean temperatures. Collaborative efforts continue globally to rebuild coral ecosystems and ensure biodiversity.
In the western Pacific, a vibrant ecosystem is thriving in an area where lifeless coral skeletons once dominated the seabed. Off the southeast coast of Mindanao, a remarkable transformation has taken place over the last six months. An innovative artificial reef composed of 3D-printed clay tiles now serves as a habitat for colorful fish, showcasing the potential of technology in marine conservation.
This artificial reef, roughly the size of ten parking spaces, was developed by the Swiss start-up Rrreefs, co-founded by marine biologist Ulrike Pfreundt. The primary objective of this initiative is to restore damaged coral reefs and protect the remaining coral populations.
Across the globe, researchers are committed to preventing coral extinction using various strategies, including the construction of artificial reefs, breeding heat-resistant coral species, and even utilizing soundscapes. The urgency is amplified by the alarming trend of rising ocean temperatures, which significantly contribute to the increasing frequency of coral bleaching events and threaten these vital ecosystems.
Pfreundt and her team engineered specialized clay modules that resemble artistic sculptures, first at ETH Zurich and later through their start-up. These modules feature undulating surfaces and myriad cavities, enhancing both the adherence of coral larvae and providing shelter for various marine creatures. The tiles fit together like Lego bricks to form a resilient reef structure.
The Success of the First Artificial Reef
The success of this approach is evident in the Philippines reef, where an abundance of corals and fish have already made it home. Rrreefs previously constructed their first artificial reef off the coast of San Andrés, Colombia, three years ago.
Regular assessments have shown promising results: “Our reef now supports twice as many new corals compared to the adjacent natural reef. Fish diversity is equally high,” remarks Pfreundt. “This achievement is not just a win for us but also for the corals and the surrounding marine life.”
Coral reefs are essential to both human livelihoods and marine biodiversity, housing a quarter of all ocean species, providing natural coastal protection, and supporting approximately 500 million people through fishing and tourism.
However, ongoing threats, such as overfishing, ocean acidification, and climate change, continue to endanger these ecosystems. Corals rely on symbiotic microalgae for nutrients and coloration. Rising temperatures can disrupt this relationship, leading to bleaching and potential coral death. The UN Intergovernmental Panel on Climate Change warns that if global warming reaches 1.5 degrees Celsius, as much as 90% of warm-water coral reefs could vanish.
Can artificial reefs save corals from extinction? Marine ecologist Christian Wild from the University of Bremen holds a cautious view. He notes that artificial reefs are most useful in areas with loose coral debris following events like dynamite fishing or storms. In these cases, solid structures, such as clay reefs, provide ideal conditions for coral larvae to settle.
Despite their benefits, artificial reefs offer limited solutions to combat rising ocean temperatures, which could still endanger newly settled corals during heatwaves. While corals can adapt to higher temperatures, the current pace of climate change outstrips their ability to evolve, according to Wild.
Yet, there is hope in the form of “assisted evolution,” which aims to expedite coral adaptation. Research led by geneticist Madeleine van Oppen at the University of Melbourne has shown that exposing symbiotic algae to gradually rising temperatures can help identify the most heat-resistant strains. Interestingly, these resilient algae can pass their heat tolerance on to corals, reducing bleaching and improving survival rates.
Combining this approach with artificial reefs like those developed by Rrreefs could significantly enhance coral restoration efforts. Pfreundt is enthusiastic about this opportunity, stating, “We are open to collaboration and have designed our reefs to effortlessly accommodate the introduction of heat-tolerant corals.”
Shading Techniques to Protect Corals
There are numerous strategies being explored to conserve coral populations, including shading techniques. Christian Wild’s research team conducted a pilot study in the Philippines using film to shield corals from harsh sunlight. Their findings revealed that shaded corals experienced less bleaching and greater survival rates during heat events, though this method can be quite expensive.
Additionally, Wild’s group is experimenting with water quality modifications by optimizing the ratios of nutrients such as nitrogen and phosphorus. Their research indicates that increased phosphorus levels, relative to nitrogen, can benefit coral health by reducing bleaching and enhancing survival chances. This approach could be applied through adjustments in wastewater treatment facilities, making it a cost-effective solution.
Another innovative approach comes from marine biologist Raquel Peixoto at the King Abdullah University of Science and Technology in Saudi Arabia. She