Undersea architecture: how concrete structures can help marine life

Undersea Architecture


Like it or loathe it, marine structures are here to stay. For a start, they’re essential for protecting coastal communities. Even with seawalls and the like, the British Isles are being eaten by the sea. Without them, we’d be gobbled up in no time!

It will come as no surprise for the environmentally-minded to learn that a lot of these structures have horrible effects on marine life. It seems that everything humans touch dooms some species or another!

Or does it?

Traditional marine architecture has had a devastating impact on delicate coastal ecosystems. But it doesn’t have to be like that. The more we learn about these habitats the better able we are to protect them.

And not just to protect them, either. It sounds too good to be true, but there may be a best-of-both-worlds solution. A solution which both defends human communities from the greedy sea and helps out struggling marine life.

Let’s take a look at the problem, and explore this game-changing solution:


How traditional coastal defences harms sea life

As things stand, the impact of coastal structures on marine ecosystems is overwhelmingly negative. In a 2019 study by Constanta Maritime University, ‘hard’ (i.e. architectural) coastal defences were found to affect marine habitats at every level, from zooplankton and phytoplankton to bird and mammal life.

The type and extent of the damage varies depending on each particular ecosystem, but common themes include:

Destruction of habitat

When building coastal defences, it’s often necessary to do things like gouge out dunes, dredge the seabed, destroy rockforms, and bury unique habitats beneath new structures.

Even when not completely destroyed, coastal structures can still make a habitat unliveable for its flora and fauna. For example, they may obstruct vital sightlines for seals and birds, or block migration routes.

Pollution during construction

It’s hard to build anything without a bit of disruption, but the construction and maintenance of coastal defences can have deeper and more lasting impacts than most construction projects.

For example, noise and churned sediment may drive sea life away. And it only takes a splash of diesel or engine grease to lower water quality. Not to mention the increased risk of construction flotsam – signage, for example, or barrier tape – ending up in the sea, where it could harm marine life.

Disruption of tidal processes

Coastal ecosystems have evolved over thousands of years to rely upon specific tidal processes. Fish species use certain currents to migrate. Crabs, birds, and so on rely upon longshore drift to wash up juicy tidbits.

The problem is that a lot of coastal defences are specifically designed to alter tidal processes. The same tides, currents, and drifts that feed and nurture marine life erode the coast in ways that are dangerous to humans.

So, things like groynes and artificial reefs can leave a coastal region changed beyond recognition for the life which relies upon it.

Changing the pH of the sea

Coastal ecosystems often need very, very specific conditions in order to thrive. For example, the plankton in a rockpool can be wiped out by a heavy rainstorm, purely because the rain changes the chemical profile of their water.

Rockpools usually recover from events like this once normal conditions are restored by the tides – but what happens if normal conditions are never restored?

Well, in that case, the impact rockets up the food chain. First, plankton-loving fish and crustaceans starve. Then, the bigger fauna who eat these animals starve. And so on, until even human communities find themselves fishing in empty seas.

What’s this got to do with concrete coastal defences? Well, like everything else in the world, concrete has its own chemical profile. When immersed in salt water, concrete defences can (and do) alter the pH of the surrounding waters in ecologically devastating ways.

What can we do?

This is a very hard problem to solve. On the one hand, human communities should not be allowed to fall into the sea. On the other, these Isles are home to some of the most unique and diverse coastal habitats in the world. Do we have the right to destroy all of this beautiful biodiversity?

Well, the good news is that it doesn’t have to be all or nothing. JP Concrete has been working closely with universities and the Environment Agency to create coastal defences which don’t just limit environmental damage – but which actively help out marine ecosystems.

Here’s how we’re doing it:


Destruction of habitat is one of the biggest problems associated with coastal defences. Replacing the nooks and crannies of habitats carved over time and tide with featureless slabs of concrete does untold damage.

But what if that concrete could, itself, be a habitat?

Biomimicry is a fascinating area of study. It’s all about looking to the designs of nature for human ergonomics and architecture. Natural forms have developed over thousands of years – and stood the test of thousands more – so it’s only logical that humans can develop better, more effective, and longer-lasting structures by turning to nature for inspiration.

For example, the intricate root structures of mangrove swamps have effortlessly protected the land along the Asiatic Pacific coast for hundreds of thousands of years. When some swamps were dug up by humans, the vital role played by the mangroves quickly became clear. The sea poured in, and coastal communities suffered. More Asiatic-Pacific coastline has been lost to the sea in the past two decades than in the preceding millenium.

However, humans are nothing if not adaptable. We learned the lesson, and began to create coastal defences which mirmic the shapes, forms, and tensile strength of the mangrove swamps. By doing this we’re not just holding back the sea – we’re also encouraging the original mangrove habitat to return.

Can we achieve the same sort of thing in the UK? Yes! Absolutely! Our biomimicry designs not only utilise the power of nature to hold back the sea, they also provide essential habitat for sea life. Those featureless slabs of concrete are gone – in their place, we provide designs which mimic the natural forms of the local environment.

Fissures, slopes, nooks, crannies, sand, sediment, and even plantlife – our designs can replace what has been lost to previous coastal defence projects. We can protect the coast at the same time as returning vital habitat to the flora and fauna which so desperately need it.


Sensicrete – self-healing concrete

Construction disruption has a huge impact on marine habitats. What’s worse, that disruption is often repeated, because coastal defences need a lot of maintenance. The combination of salt, sand, and constant battering by waves makes relatively short work of any concrete structure.

Any concrete structure but ours, that is. We can massively reduce construction and maintenance disruption with our self-healing concrete mix, Sensicrete.

Much like biomimicry, Sensicrete uses nature itself to heal cracks as soon as they appear. Sensicrete contains dormant limestone-producing microbes within its mix. If the concrete cracks, the microbes are exposed to water and oxygen. This activates them, and they begin producing limestone.

Before long, the crack is entirely filled with limestone. Having safely sealed themselves back into the structure, the microbes go back to sleep. It’s roughly the same process that’s used by coral polyps to create huge, long-lasting structures like the Great Barrier Reef.

Concrete structures that heal themselves need a lot less maintenance than traditional concrete. This saves local councils hundreds of thousands of pounds in maintenance, and means that marine life isn’t regularly disrupted by repair work.

pH-balanced concrete

Concrete doesn’t have to be chemically destructive. It’s always been possible to change the pH of concrete to match the marine environment – people just haven’t bothered before.

Well, here at JP Concrete, we always go the extra mile. If we need to alter or neutralise the pH of our concrete to protect marine life, that’s exactly what we do.

You really can have it all

Humans and nature don’t have to be in competition. We can work together to build a world that works for everyone (and everything!)

It feels like the planet is in a bleak place at the moment. But we and our partners are working hard to improve at least our little bit of it.

Solutions like biomimicry and Sensicrete prove that there is hope. A better world is possible.

For more on our eco-friendly solutions visit the Sensicrete and Eco Rock Armour pages.