Harbour's New Living Seawall

New sea life will be brought back into Sydney Harbour thanks to the pioneering use of ‘habitat tiles’ that have been fixed to North Sydney’s harbour walls.

The ‘habitat tiles’ are designed to help make seawalls more ecologically sustainable by creating a more natural environment for marine life.

They have been installed on seawalls along Sawmillers Reserve and Bradfield Park in North Sydney, making it the largest retrofit of a Living Seawall in Australia, and potentially the world.

Council has installed a full-scale sculpture of the tiles with interpretive signage ‘to tell the story’ of the project at the Sawmillers Reserve site.

This follows a 20-year partnership between North Sydney Council and Sydney-based universities on making seawalls more ecologically sustainable.

Sydney universities have successfully trialled several approaches - including artificial rock-pools and flower pots - on North Sydney’s seawalls over the years.

But the ‘habitat tiles’, developed by the Sydney Institute of Marine Sciences (SIMS) and Reef Design Lab, proved so promising after a small-scale trial in Sawmillers Reserve, even Swedish engineers’ interest was piqued, with Volvo signing up to the project in 2018.

In early October, SIMS added 108 new habitat tiles, comprising of five designs developed by the Reef Design Lab, to the seawall at Sawmillers Reserve. 

Volvo also installed 50 of their own ‘mangrove tiles’, slightly modified to mimic the root of mangrove trees, along the seawall in Bradfield Park.

Both ‘habitat tiles’ increase attachment space for intertidal species like oysters, which are vital to maintain water quality and provide food and habitat for fish. 

It takes time for disturbed areas like seawalls to be colonised by marine life but barnacles, smaller seaweeds, oysters, marine snails and limpets are expected to attach to the tiles within a year.

Over time, this colonisation is likely to grow and new species will colonise the tiles and beyond so that eventually they will be hardly visible.

The tiles are expected to remain in place until at least 2038, with their effectiveness in improving marine life to be monitored by SIMS. 

Funding for this project was provided by the NSW Environmental Trust, the Harding Miller Foundation, and the Kirby Foundation.