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A healthier harbour

How a new Opera House reef project will breathe life into Sydney Harbour

Danielle Edwards

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

Kitted out in a wetsuit with milk-crate ‘reef’ by his side, Booth, the Professor of Marine Ecology at the University of Technology Sydney (UTS), emerges from a dive off the Andrew (Boy) Charlton Pool pontoon having inspected its seaweed-encrusted underside. It’s one of the harbour transport pontoons he successfully made more ‘fish friendly’ in 2014 thanks to the attachment of a low-cost underwater milk crate habitat.

More than fifty per cent of Sydney Harbour’s shoreline has been replaced by seawalls to protect infrastructure from storms and erosion, depriving smaller fish of their natural habitats.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.

Now he’s diving head first into a three-year collaboration between the Sydney Opera House, the University of Technology Sydney and the University of Sydney to help restore marine habitats and rebalance biodiversity around Bennelong Point.

A modular artificial reef – an evolution of the milk crate prototype designed by David Lennon of Reef Design Lab – will be installed along the sides of the Opera House, allowing researchers to assess fish numbers and diversity in underwater areas.

Opera House architect Jørn Utzon was strongly influenced and inspired 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.



"Sydney Harbour is one of the finest examples of a working harbour ... it's in surprisingly good shape."

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

Professor David Booth: That’s interesting, but no, we won’t. We actually have three species of coral that natively occur here and 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.

DE: So what will the Opera House Reef Project involve?

DB: After initial scoping this year, we’ll install a modular artificial reef made up of nine pods, three each of low, medium and high complexity, each around one metre in depth and width. Over the 18-month period the artificial reef is submerged in the harbour, we’ll record baseline data on fish numbers and diversity and assess its impact on marine life. Our earlier research has shown habitat enhancements such as artificial reefs can help improve biodiversity and provide suitable habitat for native species including leatherjackets, juvenile blue groper and seahorses so we’re hopeful for similar success here.

DE: How does this project with the Opera House build on your work from 2014?

DB: 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 Hackney 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.

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

DB: 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.

Fanbelly leatherjacket in Sydney Harbour

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

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

DB: 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.

DE: Why is it important to help the small fish?

DB: 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.

DE: If successful what do you hope this project will achieve?

DB: 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.


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

DB: 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.

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

DB: 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 is expected to be installed early 2019, and will help achieve 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 and UTS.

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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