At BBC Future’s World-Changing Ideas Summit, ecologist Emma Johnston explained how our desire to conquer the ocean is putting its wildlife – and ourselves – in danger.

World-changing ideas summit

In June 2016, a violent storm lashed the Sydney coastline, hammering it with waves up to eight metres high that sent water surging up to 50 metres inland.

As a marine ecologist at the University of New South Wales, Emma Johnston knew the storms were coming and knew what potential they had. But even then, the damage they inflicted on her very own neighbourhood shocked her: a hole blasted in the wall of the local surf club, a backyard pool toppled over a beach cliff, and huge chunks washed out of the much-loved northern beaches coastline.

The incident starkly illustrates both our love for the ocean and why we fear it so much. “We love the sea, we swim into it, live near it, build beside it, 70% of the world’s mega-cities are built on coast, and we even fantasise about living under the sea,” she told the BBC Future World-Changing Ideas Summit in Sydney on 15 November.

Almost every culture has a flood myth of some kind

But we’re also terrified of it. Almost every culture has a flood myth of some kind, and our entertainment plays on this with films such as the Poseidon Adventure, Waterworld and Titanic. For much of our history, our response to this fear has been to try to control the marine environment and manage its impact on us. We resort to ‘hard engineering’ – dams, sea walls, dredged channels – in an effort to tame the wildness of the ocean. But Johnston argues these endeavours are ultimately doomed to fail. “The sea has a habit of taking back its own.”

Instead, Johnston is advocating for ‘blue engineering’ – the marine version of the ‘green engineering’ movement on land that has seen nations like Singapore reclaiming the walls and roofs of the concrete jungle with plant life.

Blue engineering isn’t just some hippie ideal; it’s a blunt necessity. We are encroaching further and further into the marine environment – 60% of China’s mainland coastline is built upon, Indonesia has plans for an enormous sea wall to protect Jakarta, and our oceans are dotted with thousands of oil rigs and offshore wind turbines with ever more being planned and built.

But this new land-grab risks doing irreparable harm to marine environments and ecosystems. These are the ecosystems that nourish the fish and marine species that constitute 16% of global animal protein intake, that are home to underwater forests as essential to the marine world as the Amazon is to the terrestrial biosphere, and which make our coastlines such wondrous and attractive places to spend time in.

“We’re loving the sea to death,” Johnston says. “We’re not been thinking about design of structures with respect to ecology.”

For example, structures such as piers create shade, which reduces algal growth and can make it easier for invasive species to take root, and changes the interactions between predators and their prey. Bright lights at night confuse species such as turtles that use moonlight to navigate. Constructions designed to slow down the flow of water and reduce wave energy can have the unintended effect of trapping contaminants. Many of these structures also rely on anti-fouling treatments to stop them from being clogged up by marine invertebrates, but these biocides can have a host of other impacts well beyond their immediate target.

Is it possible for us to co-exist with our oceans and have a neutral or even positive impact on the marine environment? Johnston believes the answer is yes. She says all around the world people are starting to restore natural habitats and foreshores; building with nature instead of in defiance of it.

One way to do this is to employ design and architecture that not only achieves its structural purpose but also provides habitats for the local marine organisms. Along the waterside Barangaroo development in Sydney Harbour, a complex, multi-layered sandstone wall provides seating for humans above the surface. It also offers an enticing environment below the surface which is already being colonised by kelp – make it one of the few kelp environments in the inner harbour. “Why can’t a sea wall also be a diving location or marine park?” Johnston says.

As a naturally occurring local material, sandstone is a familiar substrate to Sydney Harbour’s marine creatures, but researchers with the World Harbour Project are taking things one step further. Using 3D printing, they are creating tiles that mimic the natural structures found on rocky shores. These not only make for a more attractive home for marine creatures, but researchers are also actively seeding these tiles with local seaweeds and creatures such as the Sydney rock oyster, which is particularly good at trapping contaminants and improving water quality.

Twelve harbours around the world are taking part in this marine tile experiment, each working with their own unique marine life. Johnston says there are so many aspects of the tiles to be investigated: what material to make them from, how far apart do they need to be to encourage maximum biodiversity, what is the best orientation to offer protection from heat stress as waters warm.

It’s a far cry from the days when huge numbers of old tyres were dumped at sea and called an ‘artificial reef’. Those clumsy early attempts are now costing millions to remove and rehabilitate, showing just how far we have yet to go in understand how best to co-habit with the underwater world.

“Every time I dive I realise how little we know about how marine environments work,” Johnston says. But with a new mindset of retreat, restoration and blue engineering, she feels there is cause for hope. “I am looking forward to the beginning of new era of construction in marine environments.”

--

Join 700,000+ Future fans by liking us on Facebook, or follow us on Twitter, Google+, LinkedIn and Instagram.

If you liked this story, sign up for the weekly bbc.com features newsletter, called “If You Only Read 6 Things This Week”. A handpicked selection of stories from BBC Future, Earth, Culture, Capital, Travel and Autos, delivered to your inbox every Friday.