Saving the Great Barrier Reef

By Dr Christian RothApril 1st, 2016

The Great Barrier Reef is at risk from factors in and out of the water. Dr Christian Roth discusses what needs to change, and how, to save our reef.
Queensland Coastline as seen from space shows the Great Barrier Reef and muddy water flowing from hte Burdekin River into the ocean.
A thick plume of sediment can be seen washing out of the Burdekin River on the Queensland Coast and into the ocean waters of the Great Barrier Reef. Image: NASA / Flikr

The Great Barrier Reef as seen from space. A plume of sediment can be seen washing out of the Burdekin River and into the ocean waters of the reef. Image: NASA / Flikr

There are few superlatives in any language that can do justice to the uniqueness and magnificence of our Great Barrier Reef. This 2,300 kilometre long jewel nestled along Australia’s eastern coastline is home to a wealth of marine biodiversity unmatched anywhere in the world.

This jewel, however, is becoming tarnished; its complex and delicately balanced ecosystem is under threat from human activities both locally on the reef, regionally along its coastline, and globally. These impacts are being felt in deteriorating water quality, rising water temperatures, and increasing ocean acidification. They are being seen in dramatic losses in coral cover – at least half has disappeared since 1985 – as corals gradually succumb to these stressors.

Natural ecosystems are designed for resilience, but the size and scale of these impacts may exceed even the Great Barrier Reef’s capacity for recovery. Climate change will heap further insult on the already injured Reef. It needs our help, and we know it. Research from James Cook University has found that nearly 90% of Australians believe the Great Barrier Reef is under threat from climate change.

So what can we do about it? A key focus of protection and recovery efforts needs to be the catchments and coastline adjoining the Reef. Land use in these areas has a major influence on water quality around the reef. There is already evidence of increased erosion and the export of sediments from the Burdekin catchment down to the Reef lagoon; Australian researchers have shown the amount of fine sediment reaching the Great Barrier Reef from this catchment has increased up to ten-fold since European settlement [Bartley et al].

Agricultural practices such as intensive cropping of sugar cane in these areas also impact on the amount of nitrogen and pesticides entering the reef, which in turn are linked to outbreaks of the crown-of-thorns starfish, reduced coral recovery and reproduction, depleted seagrass beds, and increased disease.

Shipping, port expansions and overfishing are also posing a significant threat to the health of the Reef, and changes to the temperature and chemistry of the ocean are delivering increasingly bad coral bleaching events. While these are not the result of poor water quality, their impacts are magnified by the Reef’s vulnerable state and poor health. Agricultural pollution now threatens around one-quarter of the Reef’s total area, and is second only to climate change as a threat for coral reefs around the world.

Because of this, both federal and state Governments are taking notice of water quality as a key issue for the Reef. The Federal Government has pledged significant investments, such as the Federal government’s $140 million Reef Trust and Queensland’s $90 million GBR Water Science Taskforce. At the same time, the Queensland state government introduced water quality targets with the aim of reducing total suspended sediment runoff by up to 50 per cent and reducing nitrogen runoff by up to 80 per cent in key catchments, such as the Wet Tropics and the Burdekin, by 2050.

But with one of the worst coral bleaching events already underway on the Reef, we need to move faster, we need to do better to restore the Reef to full health.

As Australia’s national science agency, CSIRO is ideally positioned to bring the best science to the challenge and to support Federal and State governments in deciding and implementing policies to achieve this. CSIRO already has a long history of working with partners in the Great Barrier Reef World Heritage Area and its adjacent catchments; spanning the full continuum from inland to outer reef.

Eroded landscape on the banks of the Upper Burdekin River, Queensland
Dr Christian Roth (right hand side) in discussion with Dr Scott Wilkinson (CSIRO), Prof Roy Sidle and Jack Koci (University Sunshine Coast) on options to manage large alluvial gullies located on the banks of the Upper Burdekin.

Dr Christian Roth (right hand side) in discussion with Dr Scott Wilkinson (CSIRO), Prof Roy Sidle and Jack Koci (University Sunshine Coast) on options to manage large alluvial gullies located on the banks of the Upper Burdekin. Image: Dr Rebecca Bartley (CSIRO)

In this edition of Ecos, we showcase a selection of recent research by CSIRO and collaborators from institutions such as James Cook University and the Australian Institute of Marine Research. These studies have explored areas such as the long-term history of sediment run-off onto the reef by studying radioisotopes in quartz-based sediments, and looking at sediment ‘fingerprints’ to determine exactly where in catchments adjoining the Reef the sediments are coming from.

These sorts of studies help deliver the kind of fine detail that can lead to more informed, targeted and efficient interventions. Understanding the biophysical processes, as well as the social and institution drivers of behaviour around the Reef, will highlight ‘hotspots’, and enable us to tailor interventions to specifically address those.

It is also the time to take an interdisciplinary, partnership approach to the problem, rather than the more fragmented, siloed research that has taken place in the past. It is not enough to simply examine the source of sediments within a catchment without also incorporating a detailed understanding of land use practices in those areas, and social and economic factors that have led to those practices. Similarly, an intervention to reduce erosion must take into account all stakeholders, including local communities, governments, regulatory bodies and individual land owners.

It’s a holistic approach that, while challenging, can deliver more holistic solutions. It is an ecosystem-wide problem that requires ecosystem-wide change to solve.


  1. In spite of the no-doubt wonderful science that CSIRO scientists and others will do, am I alone in feeling despair at the situation? How did it come to this? No matter what insights science can bring to the situation, I can’t escape the feeling that what we are witnessing is an irreversible decay of the Great Barrier Reef to inevitable oblivion. Does anyone think I am wrong?

    1. Hi Alan. The task ahead to protect the GBR is indeed daunting and a huge challenge, for science, government, industry and civil society. It is unlikely that the GBR will disappear, but it is probable that it will change, due to things like climate change. Achieving better water quality outcomes is important to increase the resilience of the reef systems to be able to recover from events such as the current bleaching. While we work towards that goal, it buys us time to understand how the GBR will evolve in response to the trade-offs between conservation and development and climate change, a balance that ultimately society has to determine. This process needs to be underpinned by robust science.

      We will only have a hope of succeeding if we can change the way we all work together on this. I am less pessimistic than you might be, because from my perspective I see an increasing alignment and willingness of all major stakeholder groups to do precisely that. Our role in CSIRO is to help forge stronger partnerships and ensure that the breadth of science is better integrated and conveyed in a way that is much more meaningful for those involved in doing things on the ground or those charged with policy making. There is still a lot we can do better, and that is what I think matters.

  2. Ho hum guys – there is no over fishing! All is sustainable well within the bounds of various sustainability audits, green zones and so on.

    Now to the even BIGGER issue

    HOWEVER you like many others do have it wrong. Sure its partly my fault when I had Ian Prosser et al do the first ever and still most outstanding analysis of sediment and nutrient flows [ see NLWRA 2001] and ever since then the focus has been on water quality…..but even I, the father of two 5 year investments of Reef Rescue can learn new things.

    The real issue with the Reef is total loss of NPP – or net primary productivity because we have turned the catchments into pipes [and changed hydrology as well] and most importantly trashed what used to be the buffers and assimilators and productive hot spots – the floodplain wetlands. IF we can recover just part of NPP then the entire food chain will benefit, including impacting on such as algal growth and even COTS.

    I have a great innovative proposal if CSIRO would like to consider the next tranche of science to underpin GBR survival….and since I and Ian and the crew set this particular present water quality emphasis going – well its appropriate CSIRO be foremost in the next major science discovery for what the Reef needs. Christian R or whoever can contact me and we can develop my hypothesis further. regards and looking forward to underpinning the next BIG innovation for Reef health.

  3. Hi Colin,
    The trade-offs between emphasis on improving water quality from agricultural and urban land use and the need to restore coastal wetlands is part of the what I am referring to in my response to Alan above.
    Happy to talk to you about your perspective on the balance of science required.

    1. Thanks Christian – as per the draft paper I emailed you….alas we simply have not done the systems science. We don’t know the changes in net primary productivity for the ecological system or indeed where best to invest in repair. Draft final paper to come your way in next 2 weeks or so. Cheers

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