Mangroves to fight coastal erosion in world first at Altona

Councillors Sandra Wilson and Jonathon Marsden with Hobsons Bay council ranger Andrew Webster. Photo: Damjan Janevski

By Goya Dmytryshchak

A mangrove project that will fight coastal erosion is taking root in Altona.

In the world-first trial, mangroves are being grown in protective pods at Altona Coastal Park, a 70-hectare intertidal and salt marsh area just 11 kilometres from Melbourne’s CBD.

The project is headed by Melbourne University’s National Centre for Coasts and Climate in partnership with Hobsons Bay council.

Researchers planted 564 seeds collected from Port Phillip Bay at Altona, with about a fifth starting to grow leaves after 41 days.

The seeds were planted in pods designed to withstand wave forces.

Project manager and NCCC research fellow Rebecca Morris said 210 pods had been installed at Altona, with more at Grantville and Lang Lang on Western Port Bay.

“Visitors to the Altona Coastal Park may notice the grey concrete pods in the shallows,” Dr Morris said.

“They are like an hourglass in shape and will house the mangrove seedlings until they are strong enough to survive in the open.

“At this stage, 21 per cent of the seedlings inside the pods have sprouted – which is about what was expected – but they are very fragile and we will continue to monitor their growth with the hope of planting more seedlings in early 2020.”

Members of the community are being asked not to get too close to the pods to allow the mangroves to become strong.

Cr Sandra Wilson, who holds the environmental sustainability portfolio, said one of the aims of the project was to raise awareness of more nature-based solutions for defending coastlines.

“Mangroves prevent coastal erosion due to the complex root systems that grow above and below the surface,” she said. “Roots which grow beneath the surface help bind soil, while the aboveground roots reduce wind and waves.”

She said the project was funded by a Department of Land, Water and Planning grant.

Hobsons Bay mayor Jonathon Marsden said it was hoped the defence against coastal erosion could be used to protect other foreshores.

“From designing custom-made pods to house the mangrove seeds and protect them from the coastal elements to harvesting the seeds and planting them at the coastal park, it has been quite a journey,” he said.