How structures made from oyster shells can help prevent coastal erosion

Named Erosion Mitigation Units, the domes are two metres wide and form a barrier around 60 metres offshore.

This organic shape helps to maintain their structural integrity, minimise material use, and create habitable colonies for ocean life.

To create the domes, the team in Melbourne used digital moulding analysis alongside traditional casting techniques. This allowed for the development of a reusable precast mould that uses less concrete than 3D printing techniques.

When it came to building the structures, Reef Design Lab added crushed-up locally sourced oyster shells with concrete before pouring it into the moulds. The unique shape and geometric patterns of the modules were chosen to create favourable conditions needed for marine species to live on them.

A slight overhang provides a spot for stingrays and pufferfish,  Inside the tunnels and caves of the module, octopus, smaller fish, and crustaceans are able to hide from larger predators. These inlets also offer shade for sponges and cold water coral to latch onto.

The surface of each module was intentionally left rough to the touch in hopes of being able to attract reef-building species such as worms and shellfish, in particular, mussels and oysters.

As they needed to be placed in shallower waters to complete their job as breakwaters, the modules were designed to retain water in order to shelter intertidal species during low tide periods.

Reef Design Lab installed 46 of its domes beneath the shallow waters of Port Phillip Bay last October. Over the next five years, they will be monitored by the Melbourne Universities Centre for Coasts and Climate to see whether they complete their job while attracting sea life.

Only six months after the modules were installed, numerous species of shellfish, sponges, and cold-water corals have been seen living in and around them. This is great news, as it means the structural design and surface texture are successful.

As storms increase in strength and frequency due to our planet’s changing climate, natural and eco-friendly solutions like the domes made at Reef Design Lab will be welcomed by those living in other coastal areas of Australia.

With a design that is proven to work, it wouldn’t be surprising if we saw them popping up all over the world.