A breakwater built in the early twentieth century in Wales. Research has shown that shorelines hardened with artificial structures have up to 45 percent fewer species than natural ones in similar locations. Photo by ceridwen.

Can Eco-Engineering Help Revive Wales’ Coastal Waters?

Scientists are working to reduce the ecological impacts of breakwaters along our ever-more urbanized coastlines.

While coastal tiling does not immediately bring to mind the development of biodiversity, in this case, its aim is exactly that. By conducting a long term field-based research effort, the Eco Structure project hopes to determine what combination of materials and shapes, when affixed to coastal defence structures, renewable energy infrastructure, and other marine-based construction, might best help ecologically barren coastal areas become filled with marine life again. In doing so, they are trying to address a fundamental challenge around coastal development: Research has shown that shorelines hardened with artificial structures have up to 45 percent fewer species than natural ones in similar locations.

In a time of rising sea levels, plummeting marine biodiversity,and growing human populations, whether or not man made coastlines make good habitats for marine life is a serious issue. As coastal cities grow, their shores become harder. In major coastal urban areas — like New York, Hong Kong, and Sydney — more than 50 percent of the coastline is composed solely of artificial structures such as piers and seawalls. Up to one billion people are likely to be at risk of coastal flooding by 2030, which means many more coastal areas are likely to be “hardened” to protect them

Evans and her team are researching ways to “eco-engineer” coastal artificial structures to make them look and act more natural. The theory is that by mimicking natural rocky shorelines, manmade structures can significantly increasing biodiversity; that “complexity will attract diversity of life,” as Evans says.  “What we are hoping is that the extra layer of topography we are adding will attract more diverse communities more like what we might see on a natural habitat,” she adds.

Evans says many of the ecological problems posed by traditional coastal structures are the result of the materials they are made from. She points out, for example, that “Rock Surfaces on a breakwater tend to be quite smooth compared to natural rocky habitats, which makes it much harder for marine life to take hold.”

It is also becoming evident that hard artificial structures placed in environments with no normal hard structures can have further negative ecological consequences. A growing body of research points to hard features built on sandy shorelines as “stepping stones” for the movement of destructive non-native species into these areas. Researching how artificial structures facilitate these movements (and how climate change might alter them) is also a significant part of the Eco Structure project.

Poorly planned coastal engineering can even lead to increased erosion in areas it was designed to protect. The historic seawall surrounding Stanley park in Vancouver, Canada, for example, has been directly linked to increased and costly erosion in nearby areas. Mistakes made within the wall’s design may cost the city hundreds of millions of dollars to rectify or may mean removing the seawall (a popular tourist attraction) altogether.

Perfecting seawall design is all the more urgent given human-caused climate change. The Global Climate Forum predicts that coastal flooding could cost up to one trillion dollars per year in repairs by 2100 if current sea-level rise projections hold true. Efforts to address this flooding are likely to result in more seawalls.  

In what might be described as a natural “copy and paste” approach, one of the techniques being pioneered by the Eco-Structure team is coastal photogrammetry using 3D laser scanning radar (LIDAR). This technique is used on biodiversity-rich natural coastal structures such as boulders and rock pools to model their shapes and topography. The models are then 3D printed and reproduced as artificial tiles that, when stuck to man-made structures, will hopefully attract the same sorts of species that their natural counterparts do.

Learning from nature, the project has already come up with some interesting material technologies such as a new type of concrete termed “Reef Crete” which models the topography and texture of a natural reef while also being eco-friendly by using low carbon materials and production methods during construction. The team has also developed new styles of clam-like “vertipools” which will hopefully attract native species of mollusks, bivalves, and seaweeds. One of Eco Structure’s main goals is to come up with a definitive database of what works and what does not in terms of ecosystem friendly materials and structures that can be applied globally in similar ecological settings.

Similar techniques are being trialed independently elsewhere. In the Agathoise coast Marine Protect Area in France, 32 3D printed artificial reefs were emplaced earlier this year to form a base for a harbor indicator buoy. This is the largest installation of any kind of coastal eco-structure yet.

Unfortunately, determining whether Eco Structure’s efforts will bear fruit that can truly revitalize our coasts will not happen overnight. As Evans says, “It takes some time for marine communities to colonize new surfaces and it could take up to two years before we see if our efforts have been truly successful or not.”

While it may take time to see results from the Eco Structure project, the potential benefits of eco-engineered structures could be vitally important to ensuring sustainable development. In a warming world with rapidly growing human populations, eco-engineering points us towards a future where human structures can co-exist within biodiverse eco-systems.

Robbie Galvin

Robbie Galvin is a science communicator and writer based in southeastern Ireland.

See Earth Island Journal article . . .