Port Phillip Bay: restoring lost and forgotten reefs
100 years ago, Port Phillip Bay was home to an extensive oyster and mussel reef system that supported a vast range of other sea life including not only a variety of marine animals, but also the sponges and seaweeds necessary to form a habitat and a thriving reef. Sadly, after many years of mass exploitation, overfishing and pollution these reefs are gone. The benefits of these reefs are massive and can be seen through social and economic benefits as well as water quality.
Ambitious,
broad-scale restoration
Leading Australia’s largest marine restoration initiative, The Nature Conservancy has committed to protect and restore 60 shellfish reefs right across the Great Southern Reef with the aim of recovering the critically endangered marine ecosystem. This includes the habitats in Port Phillip Bay where we were able to spend a day with these leading marine researchers looking for a new suitable shellfish restoration site within the bay.
Careful site selection
In order to assess a potential shellfish site, the researchers conduct an observational dive according to their suitability modelling benchmarks, which look at criterion such as depth and proximity to existing seagrass meadows as well as evidence of a previous existing shellfish reef. On this particular dive they found positive signs for restoration of this area including some of the largest oyster shells that they had ever seen.
Long term benefits
Once the location for the new reef is decided upon, they use tonnes of recycled oyster and mussel shells from wholesale seafood retailers and restaurants in addition to limestone rubble to form the foundations of the reef. The shells eventually cement together creating the reef structure. Every hectare of new reef will create 375kg of new fish stocks each year, including highly valued species like flathead, snapper and whiting. In addition to valuable fishery resources, the shellfish filter large volumes of water and create many new habitats and homes for other reef dwelling species.
