Living Seawalls Boost Marine Biodiversity on Hardened Coastlines

A global initiative called Living Seawalls is retrofitting seawalls, marinas and piers with biodiversity-friendly panels designed to make hard coastal infrastructure more hospitable to marine life. Ireland's first installation went up at Kennedy Pier in Cobh in September 2025, where early monitoring shows marine species beginning to colonise the textured concrete panels. While studies indicate the panels can lift biodiversity and keep surfaces cooler than flat seawalls, researchers caution that questions remain over their effect on wave defence, prompting calls for design refinements.

 

The Concept Behind Living Seawalls

 

Living Seawalls is a global project aimed at making hard coastal structures more welcoming to marine wildlife. It installs biodiversity-friendly panels, boulders and pilings on seawalls, marinas, piers and similar infrastructure. The initiative was spearheaded by the Sydney Institute of Marine Science and the company Reef Design Lab, both based in Australia. Its central purpose is to give nature a helping hand amid parallel climate and biodiversity crises. The approach seeks to align coastal construction with ecological function rather than treating the two as opposed.

The project responds to the increasing hardening of coastlines around the world. Growing human populations and expanding industries are driving more coastal development, while rising sea levels heighten the need for seawalls to guard against erosion and flooding. As this construction displaces habitat for marine life, Living Seawalls attempts to help people build with nature instead of against it. Project researchers frame the effort as one of many human responses to biodiversity decline. The focus falls specifically on the urbanised, built coastal environment.

 

A Response to a Marine Construction Boom

 

The initiative grew out of concern over the rapid expansion of coastal construction globally. Project co-founder Melanie Bishop points to research showing that half of the foreshore in Sydney Harbour has already been hardened with seawalls. Global marine construction is projected to rise by 23 percent between 2018 and 2028. Bishop describes the current period as a construction boom in the oceans. This scale of building forms the backdrop against which the project was conceived.

A core problem is that most marine construction produces smooth, featureless surfaces. These lack the protected spaces that many species need to shelter and thrive. Living Seawalls seeks to address this by adding ecologically inspired surfaces to both existing and new structures. The aim is to boost biodiversity while reducing the environmental impact of urban infrastructure. This reframes coastal defence as an opportunity to support marine life rather than simply exclude it.

 

Design and Global Rollout

 

The panels were developed to imitate the complexity of natural rocky habitats. Working with Melbourne-based Reef Design Lab, the team drew inspiration from the rocky shores of Sydney Harbour. Industrial designer Alex Goad created panels that mimic rock pools, crevices and honeycomb-like sandstone patterns, alongside the textures of mangroves and shellfish reefs. The company produced nine ecologically inspired designs plus a featureless control panel for comparison. This control allows researchers to isolate how the textured surfaces influence marine colonisation.

From an initial installation in Sydney in 2018, the project has expanded widely. Panels have since gone up at dozens of seawalls across Australia, with living boulders installed at several locations. The initiative now reaches sites in ten other countries, including Plymouth in the United Kingdom and Boston in the United States. It has contributed custom pilings for a port terminal expansion in Posorja, Peru, and installed 1,000 panels at Jebel Ali Port in Dubai, with thousands more planned by 2028. Regular scientific monitoring underpins the rollout, allowing the team to adapt and optimise designs for different environments.

 

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The Cobh Installation and Colonisation

 

Ireland's first installation began in September 2025 at Kennedy Pier in Cobh, County Cork. The site features 60 hexagonal concrete panels bolted into a centuries-old harbour wall, with ridged, textured and pitted surfaces that trap or filter water with the tide. Because the panels were installed after the summer recruitment period, when many species release larvae, colonisation has been gradual. By early 2026, green seaweed dominated the panels, with only scattered snails such as periwinkles and dog whelks present. Researchers view this as an early stage rather than a measure of eventual success.

Scientists expect the picture to change as ecological succession advances. Monitoring researcher Corryn Knapp describes a standard colonisation process, beginning with microorganisms and green algae before more complex communities develop. As the panels mature, she anticipates barnacles, red algae and several types of brown wrack taking hold, along with more grazing snails. Each species contributes a distinct ecological function, from providing food and shade to improving water quality and preventing any single species from dominating. Greater species diversity, researchers note, tends to make the resulting system more resilient to disturbance.

 

Public Engagement and Practical Tensions

 

The Cobh site was chosen partly for its visibility and public accessibility. Its location near the landmark St Colman's Cathedral ensures a steady flow of passersby throughout the year. Project researchers have used the installation to engage local schoolchildren and encourage people to reconsider how human-made structures can coexist with marine ecosystems. This educational dimension is treated as a deliberate goal alongside the ecological aims. Reaching a wide audience was a central factor in selecting the pier.

The installation also highlights a practical tension at working waterfronts. The slipway must be cleaned regularly for health and safety, since green algae growth can make the surface dangerously slippery. This creates a conflict between encouraging marine life on the panels and preventing it immediately alongside them. The Port of Cork carries out monthly power washing on the pier but deliberately excludes the Living Seawalls installation from cleaning. This compromise allows the ecological experiment to proceed without compromising public safety.

 

Engineering Questions and Ongoing Research

 

The project's main open question concerns its effect on wave overtopping, when water spills over coastal defences. A laboratory study led by Franz Bauer found that the panel types at the Plymouth site actually increased overtopping because of their texture. Once seaweed and marine life colonised the panels, this effect was reduced but not eliminated. Bauer suggests that slightly different panel designs might mitigate overtopping while still supporting biodiversity. He maintains the panels can help reduce biodiversity loss by making seawalls as ecologically functional as possible.

Researchers stress that placement and design refinement will be key to reconciling ecology with engineering. Bishop notes that overtopping effects depend heavily on where panels sit relative to wave action, and that they are rarely placed at the top of seawalls as they were in Bauer's experiments. She points to simple modifications, such as angling panels, as a way to enhance wave dissipation. A separate study led by Bauer found the textured panels reduced surface temperatures more than flat ones, an effect strengthened by marine colonisation. For the project's investigators, each installation advances a long-term effort to understand how coastal infrastructure can serve both people and nature.