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Aerial shot of Sydney Opera House and Bennelong Point. Image: Hamilton Lund

A healthier harbour

A pioneering reef project is breathing life into Sydney Harbour

Danielle Edwards

David Booth is no stranger to what lies beneath Sydney’s famous harbour.

Kitted out in a wetsuit, Booth, the Professor of Marine Ecology at the University of Technology Sydney (UTS), emerges from a dive off the eastern side of the Sydney Opera House having inspected the artificial reef for the first time since its installation a few weeks prior. He and fellow marine ecologist, wife Giglia Beretta, are beaming – they’ve spotted an octopus taking shelter beside the reef.

More than sixty per cent of Sydney’s harbour shoreline has been replaced by seawalls to protect infrastructure from storms and erosion, depriving smaller fish of their natural habitats. It’s a problem Professor Booth’s research is working to redress.

In May 2019, a modular artificial reef was installed alongside the Opera House sea wall as part of a three-year research project to restore marine habitats and rebalance biodiversity around Bennelong Point. Created by Alex Goad of Reef Design Labs, the reef is made up of hexagonal pods constructed from marine-grade steel and concrete with elements of 3D printed design. Over time, the reefs will become encrusted with seaweed and sea life, providing a home for smaller fish species.

Opera House architect Jørn Utzon was strongly influenced by nature, and Sustainability Manager Emma Bombonato sees this initiative as “continuing his legacy by inspiring greater community awareness of the marine environment around Bennelong Point”.

We spoke to lead researcher Professor Booth about the future of marine life in Sydney Harbour and how the Opera House Reef Project seeks to enhance it.

UTS Professor David Booth in 2017
High-complexity reef pod installed in May 2019 Image: Alex Goad

Can we expect our own Great Barrier Reef at the Opera House?

That’s interesting, but no, we won’t. We actually have three species of coral that natively occur here, and we are studying the spread of a more tropical coral in Sydney right now. Maybe one day we will see a big shift towards a tropical ecosystem, but that’s not going to be for a while yet. Meanwhile we have nearly 600 species of fish and huge biodiversity here despite the edges of the harbour being man-made with seawalls.

How does this project with the Opera House build on your previous research?

We’ve been interested in how fish interact with artificial habitats for a long time and one of those projects involved looking at pontoons around the harbours of Sydney (that’s Botany Bay), Pittwater, Port Hacking and Sydney Harbour itself. In 2014 we conducted a two-year study looking at small enhancements under those pontoons and found we attracted some fish that would have not otherwise have been there including some commercial species juveniles, and so this naturally leads on from that.

Opera House Artificial Reef Project

Press play to watch video

What’s the state of Sydney Harbour at the moment? Is it healthy?

Like any urban harbour with millions of people around it there are some issues but I’m pleased to say Sydney Harbour is one of the finest examples of a working harbour that actually has biodiversity. In spite of pressures with stormwater, sewage run-off, dredging and seawalls it’s doing pretty well at least in the water column. If you dig into the sediment there are some issues there of course, with the past use of heavy metals and dioxins so we have to be very careful to not release those, but as it stands it’s in surprisingly good shape.

What are some of the threats to marine life in our harbour?

There are a gamut of threats that could potentially affect the harbour. One of the big ones at the moment is global warming, which is one of the results of human-caused climate change. In Sydney Harbour and Sydney surrounds the winter and summer temperatures are a little bit warmer than they used to be. Sea level rise and fresh water input are additional other climate change effects. We’ve done a lot of cleaning up of Sydney Harbour but there’s still a long way to go with threats from previous industrialisation and human pressures like stormwater runoff and, to a certain degree, overfishing.

Why is it important to help the small fish?

We would like to think using our modern knowledge and technology we can actually redress some of the imbalances from the past. Sydney Harbour, as you can imagine hundreds of years ago, was a natural harbour with mangroves and natural shorelines and that has been gradually replaced by artificial shorelines. Even though the project doesn’t return it to nature, it redresses the balance a little bit and enhances the near-shore biodiversity.

If successful what do you hope this project will achieve?

Onsite we’re hoping it attracts fish that probably were here naturally but may not use the rock walls. I’d like to think it’s a model for other areas too so we can produce something that’s viable and interesting enough to people that they use it elsewhere around the world. There are lots of urban harbours that this could be applied to.

Alex Goad, David Booth and Gigi Beretta installing the artificial reef pods Image: Alex Goad

"[Using] technology we can actually redress some of the imbalances from the past."

How did you get involved in the marine environment? Where did that passion come from?

I knew I was always interested in biology, I had and still have great insect collections of butterflies and things. I remember going to New Guinea in 1971 and that was quite an eye opener. There I saw coral reefs already degrading by human use around Port Moresby. That’s probably the first time I looked at the marine environment.

How can everyday people help to protect the marine environment in Sydney?

There are a few things you can do. For starters, appreciate our unique marine environment. Go snorkelling, swimming, take a ferry, and pass on your enthusiasm to others! Minimise pollution – don’t discard plastic food items or other rubbish. Cigarette butts and lost fishing lines and rigs are particularly problematic. Finally, understand what the issues are. Learn about stormwater, harbour development, overfishing, and make your opinion count. For example, comment via local council on proposed developments that may affect our marine environment.

The artificial reef was installed in May 2019, and will help achieve biodiversity goals set out in the Opera House’s Environmental Sustainability Plan.

The Opera House Reef Project is being funded through an $86,000 NSW Government Restoration and Rehabilitation grant, with further in-kind contributions from the Opera House, the University of Technology Sydney and collaborators the Sydney Institute of Marine Science.

Did you know the Opera House is one of only a handful of World Heritage-listed buildings to have achieved green certification globally? Find out more about Environmental Sustainability at the Opera House.

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