Marine incursion: Study finds 0.5% of world’s ocean floors now affected by construction

A world-first study indicates that construction has taken place on some 30,000 square kilometres of the world’s ocean floors, raising alarm over its effect on marine biodiversity.

Since the mid-20th century, human incursion into oceans has rapidly expanded with the construction of tunnels and bridges, oil and gas rigs, wind farms, ports and marinas, fish farms and artificial reefs.

The area modified by human construction was equivalent to around 0.008% of Earth’s ocean surface.

But the proportion leaps to more than 0.5% when impacts on surrounding areas, such as changes in water flow and pollution, are taken into consideration, said the team of scientists led by the University of Sydney’s School of Life and Environmental Sciences and the Sydney Institute of Marine Science.

University of Sydney’s Dr Ana Bugnot, lead author, said marine development occurs mostly in coastal areas, which are the most biodiverse and biologically productive ocean environments.

"Since the mid-20th century, ocean development has ramped up, and produced both positive and negative results," she said.

"For example, while artificial reefs have been used as ‘sacrificial habitat’ to drive tourism and deter fishing, this infrastructure can also impact sensitive natural habitats like seagrasses, mudflats and saltmarshes, consequently affecting water quality.

"The future projects are alarming. For example, infrastructure for power and aquaculture, including cables and tunnels, is projected to increase by 50% to 70% percent by 2028. Yet this is an underestimate: there is a dearth of information on ocean development, due to poor regulation of this in many parts of the world."

She urged greater action from international initiatives such as the EU Marine Strategy Framework Directive.

The research was published in Nature Sustainability.

Researchers warned that people’s need for defences against sea level rises and climate change would further drive ocean construction.

Image: Aquaculture farms in the coast of China’s northeast province of Liaonin (Credit: NASA Earth Observatory)

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