The Great Southern Reef is a network of temperate rocky reefs that spans more than 8000 kilometres of the Australian coastline, from Kalbarri in Western Australia to northern New South Wales. It was first described as an ecological entity in 2016 to raise awareness about the immense social, cultural, environmental and economic value of kelp forests.
From an ecological perspective, the Great Southern Reef is remarkable for its high levels of productivity, biodiversity and endemism. The golden kelp forests that dominate the temperate reefs interlink with other coastal habitats including giant kelp forests, seagrass meadows, sandflats, mudflats, saltmarshes, mangrove forests, oyster reefs and sponge gardens. They also connect with deeper habitats along the continental shelf.
A major concern is that kelp forests are rapidly diminishing due to ocean warming, marine heatwaves and pollution. In 2011, 96,300 hectares of kelp forest were lost in Western Australia. Tasmania has already lost about 95% of giant kelp forests, which are now listed as Endangered under the Environment Protection and Biodiversity Conservation Act 1999. Warm-affinity species are moving south, transforming reefs and local ecosystems. For example, long-spined sea-urchins have caused the collapse of 15% of reefs in Tasmania and are projected to degrade 50% of reefs by 2030. At the warm edge of their distribution, kelp forests are also threatened by the range expansions and growing populations of tropical herbivorous fishes, which can overgraze kelp or prevent its recovery from marine heatwaves. Human population growth is a further source of pressure.
About two thirds of the Australian population live right next to the Great Southern Reef, yet little research has been done to identify and evaluate the ecosystem services it provides. Accurate estimates of the contribution of kelp forests to society and the economy are needed to support monitoring and evidence-based management. In a global context, quantifying and assessing the benefits of Australia’s kelp forests is relevant to the UN Decade of Ocean Sciences, the UN Sustainable Development Goals, ocean accounting, and guiding efforts linked to the UN Decade on Restoration.
This Marine and Coastal Hub project generated a first estimate of the ecosystem services provided by the Great Southern Reef and their economic value.
Approach and findings
The project team compiled and synthesised existing data on the ecosystem services provided by shallow (0–50 m) rocky reefs dominated by kelp forest habitats along the Great Southern Reef, including market and non-market values. They estimated the value of these ecosystem services and highlighted knowledge gaps. The available biophysical data were aligned with existing accounting standards to ensure compatibility with ongoing and future efforts, to facilitate management and policy targets and ultimately to support evidence-based decision making.
Most of Australia’s kelp forests are managed independently by the five states in which they occur: Western Australia, South Australia, Tasmania, Victoria, and New South Wales. The benefits of these services were therefore quantified for each of these states separately. In total, more than 17 million Australians live within 50 km of the reef. Reef-associated values and activities include:
- 26 wild seaweed harvest companies;
- 115 tourism SCUBA operators;
- 1436 mapped dive sites;
- 18 million tourist visits annually;
- 16 temperate marine biology university programs;
- 43 books and films;
- key medical products;
- 23 tonnes of harvested seaweed;
- 1116 grams of carbon per m2 used for growth each year;
- 2361 peer-reviewed scientific publications from 1976 to 2022;
- 186 marine protected areas;
- 2.16 million recreational fishers; and
- more than 28 commercial fisheries with 20,000 tonnes of biomass taken each year.
To understand the importance of improving management, we estimated the total economic value that would be lost if the Great Southern Reef continues to be adversely affected by climate change and other anthropogenic pressures. We used a hypothetical, but plausible, scenario of losing 20% of Great Southern Reef ecosystem services over the next 20 years.
A 20% loss of each ecosystem service category over the next 20 years would result in the loss of the following economic benefits:
- commercial fishing ($65 million);
- carbon sequestration ($74 million);
- nutrient cycling ($12,726 million);
- recreational fishing ($3274 million);
- diving and snorkelling ($791 million);
- other recreation ($3603 million); and
- existence value ($8830 million).
The cumulative total economic value of $29.4 billion illustrates the potential benefit gained by preventing further decline of the Great Southern Reef.
Next steps for quantifying the value of the Great Southern Reef
Ocean accounts organise data on ocean-based attributes and activities such as biodiversity, tourism, resource management and nutrient cycling in a spatially explicit manner, with the overarching aim of characterising the status of the natural wealth of the ocean and quantifying changes.
We evaluated how the biophysical values collected here may be combined to create a national ocean account for kelp forests and the Great Southern Reef. The main barrier to such an account is the lack of comprehensive habitat mapping for kelp forests and other biotic habitats across the reef. Further, very little of the ecosystem services were spatially explicit. Higher resolution data are therefore needed to create an ocean account.
This project took the first step in the iterative process of quantifying the economic value of ecosystem services provided by the Great Southern Reef. The Australian Department of Climate Change, Energy, the Environment and Water, state agencies, industries and coastal communities have ocean accounting methods and foundational knowledge that can be updated as more and higher quality data become available.
Video investigates the challenge of quantifying ecosystem benefits
A challenge when quantifying the benefits provided by ecosystems is to wrangle them into common comparable metrics. How does one compare the value of cultural history and practices that have continued for thousands of generations with the value of contemporary tourism on the Great Southern Reef? This video investigates this question and reveals new figures on the economic value of the Great Southern Reef.
Great Southern Reef
University of New South Wales
Department of Climate Change, Energy, the Environment and Water
NSW Department of Primary Industries
Technical report – Project 1.9
Quantifying the ecosystem services of the Great Southern Reef
Eger AM, Bennett S, Zimmerhackel J, Rogers A, Burton M, Filbee-Dexter K, Wernberg T, Gacutan J, Milligan B, Vergés A (2022) Quantifying the ecosystem services of the Great Southern Reef. Report to the National Environmental Science Program. University of New South Wales.