Case Study 32
Science-Based Catchment Management is Evolving
along the Great Barrier Reef of Australia
Katharina Fabricius, Jon Brodie, Jane Waterhouse and Hugh Yorkston
Case s tudy 32
The challenge
The Great Barrier Reef (GBR) is the world’s largest reef system (with about 12% of the world’s coral reef area) and almost
the whole area is covered by a multi-use marine park. About 33% of the Great Barrier Reef (GBR) is completely protected
from fishing and exploitation. However, the GBR is particularly vulnerable to terrestrial runoff of sediments, nutrients and
pesticides, especially from expanding and intensifying agriculture. The GBR is located on a shallow and wide continental
shelf that traps incoming materials from 35 major river catchments along the more than 2300 km length. Therefore,
reducing the damage coming from these catchments presented a particularly challenging task for management. The initial
focus for management was to address the obvious direct inputs of pollutants from urban areas, such as discharges from
sewage treatment plants, by regulating waste management facilities and establishing best practice standards. However,
the science was beginning to identify that the discharges from agricultural lands into rivers was providing a far greater
proportion of pollutants (more than 80%). Therefore, this task needed, and has since received, robust scientific evidence
and strong public support to show that conservation of the GBR is important. However, there was vigorous debate until
the early 2000s about whether river runoff was really a problem, and if it was, then what should be done to reduce the
effects of terrestrial runoff on such a large system.
The ‘Reefs at Risk Revisited’ assessment by the World Resources Institute in 2011 confirmed the need for urgent action by
reporting that virtually all near-shore reefs of the central and southern GBR are in the categories ‘medium threat’ or ‘high
threat from local runoff’.
What was done?
From the 1980s the Australian Government, supported by the Queensland State Government, provided considerable
funding for scientific research and monitoring to trace terrestrial runoff from the catchment and the way this was
affecting the downstream coral reefs. In 2003 the joint Australian and Queensland State Government’s Reef Water Quality
Protection Plan (Reef Plan) was developed. Reef Plan provided the ‘toolbox’ for addressing this complex issue. This was
further supported by a government-initiated review which assessed the economic value of the GBR and concluded that
the GBR contributes about AU$6 billion dollars and more than 50,000 jobs into the Australian economy each year
(2005-06). The research results provided strong evidence of the impacts of land-based runoff, including increases in
macroalgal cover and decreases in coral biodiversity and number of new young corals establishing on reefs exposed to
runoff. Much of this research was based on: identifying natural environmental gradients (selecting similar structured
reefs along water quality gradients from turbid to cleaner water); quantifying water quality along this gradient, especially
turbidity, particulate nutrients and pesticides; and simple and low-tech counts and assessments of abundance and
diversity of corals and coral juveniles, macroalgal cover, and the density of larger bioeroding organisms that bore into
massive Porites corals along these environmental gradients.
In 2004-05 the Great Barrier Reef Marine Park Authority (GBRMPA) established a comprehensive water quality and
ecosystem health monitoring program, based on the indicators developed by these research programs. In monsoonal
flood plumes, they measured the rate of discharge of nutrients and pesticides and determined whether these
concentrations exceeded the physiological limits of coral reef organisms. Researchers also tracked the source of the
contaminants back up the rivers to particular agricultural and urban development activities in the GBR catchment;
sediments and particulate nutrients particularly came from beef grazing and urban development lands, while dissolved
nutrients and pesticides came mostly from cropping lands (sugarcane, banana, horticulture, grains and cotton).
This research clearly showed the links between what was happening in the catchment areas and the coral reefs, some as
far as 50 km from the coast. For example:
• The amount of nutrients exported to the GBR has increased by 9 times for phosphorus and 6 times for
nitrogen since the first agricultural development of the catchments (in 1830). These increases are driven by
applications of fertiliser on sugarcane, horticulture and other cropping areas in the catchments and losses of
particulate bound nutrients from agricultural and urban lands due to soil erosion;
• The amount of sediment exported to the GBR in river discharges has increased 6 times since 1830. Intact
tropical rainforests and grasslands release very little sediment; whereas overgrazed grasslands, some cropping
practices and urban development activities produce high sediment loads;
• Pesticides such as diuron and atrazine were found widely in inshore GBR waters and are a risk to the plant
communities of this area (coral, seagrass and algal communities);
• The majority of pollutants are exported to the GBR in high river flow discharge events and dispersed as large
flood plumes over long distances in the GBR;
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The Governments and the GBRMPA responded by:
• Supporting ongoing research into the sources and fates of pollutants in the GBR and its catchment to better
understand their impacts on the coral reefs;
• Establishing and supporting community based regional natural resource management bodies to provide
community engagement and delivery mechanisms for planning, target setting and identification of
management actions to address the decline in water quality. These are supported by incentive schemes;
• Developing specific GBR Water Quality Guidelines which identified clear trigger levels for key water quality
parameters to maintain healthy coral reef ecosystems;
• Providing support for developing catchment level water quality improvement plans (WQIPs) that used these
guidelines to establish effective water quality targets and actions to achieve them; and
• Implementing a comprehensive monitoring and modeling program to report on changes in water quality and
the health of nearshore ecosystems, including seagrass beds and coral reefs.
How successful has it been?
This strong scientific evidence was provided as regular updates to the public and government leaders by GBRMPA, NGOs
(particularly the World Wildlife Fund) and the scientists. Since the late 1990s there has been a significant shift in public
support for action to address the problem of terrestrial runoff into the GBR. Governments at all levels became convinced
of the need to halt and reverse the decline in water quality entering the GBR from coastal development and runoff from
urban and agricultural lands (See Case Study 30 Creek to Coral p. 98). This was embodied through the development
of Reef Plan in 2003. In 2008, the Australian Government provided a further AU$200 million over 5 years through the
‘Reef Rescue Initiative’ to encourage improved agricultural management practices designed specifically for farmers’
individual land types and activities. In addition, following a review of Reef Plan in 2008 and a streamlining of its actions,
the Queensland State Government introduced specific new regulations in 2009 which require most farmers (especially
sugarcane farmers) in priority management areas to have environmental management plans which govern fertiliser
application rates and the use of certain pesticides. This is called the Queensland government’s Reef Wise Farming program
(www.reefwisefarming.qld.gov.au). The Reef Plan specifies that reductions in suspended sediment exports of 20% are
required by 2020, and reductions in nitrogen, phosphorus and pesticide exports of 50% by 2013. Progress towards these
Reef Plan targets is to be measured by a comprehensive ‘paddock to reef’ monitoring and modelling program and the first
Reef Plan Report Cards, following the release of Reef Plan (2009) will be released in 2011.
Case s tudy 32
• The increasing concentration of phytoplankton in the water was linked to an increased probability of
population outbreaks of the coral eating crown-of-thorns starfish, Acanthaster planci. These starfish have
devastated large areas of the GBR between 1960 and 2006; and
• Scientific studies showed that macroalgal cover increased markedly and biodiversity declined in turbid water.
That is where water clarity is less than 10 m Secchi depth (a simple and effective tool to assess water clarity,
by measuring the water depth where a black and white disk 20 cm in diameter disappears from vision),
and where chlorophyll a in the water column exceeds 0.45 µg L-1 (chlorophyll is a proxy for phytoplankton
abundance and increases in response to nutrient enrichment).
Improved management practices are being introduced with the help of the Reef Rescue Initiative which provides financial
incentives for:
• Improving pasture cover in beef grazing lands to minimize soil erosion through strategic fence building and
rotation of cattle between paddocks;
• Restoring riparian vegetation in beef grazing lands by fencing, off-stream watering points and management of
cattle in the riparian areas;
• Using frequent soil testing and leaf analysis in sugarcane crops to reduce fertiliser application so as to just
meet crop requirements and no more;
• Managing pesticide loss by better application techniques e.g. banded spraying (i.e. spraying in narrow bands
where the weeds are) rather than whole-of-paddock spraying; and
• Continuing support for trash blanketing in sugarcane cultivation and stopping burning i.e. retention of the
sugarcane leaves on the ground after harvest to form a trash layer which prevents erosion.
Continuing research is helping to refine agricultural ‘best management practices’, develop improved and robust
bioindicators for reef health and understand the cumulative effects of poor water quality and climate change on reef
health.
Furthermore, GBRMPA established the ‘Reef Guardians’ program in 2004 to recognize and support stewardship activities
taken by local councils and to develop an environment-based education program for schools. This program aims to
improve water quality and land management practices in towns by building capacity in local government and developing
local action plans to better manage vegetation, sewage and stormwater and engaging the community in undertaking
sustainable environmental management practices. All 13 local governments adjacent to the GBR coast are now engaged in
this program. Similarly, the ‘Reef Guardian Schools Program’ has engaged over 200 local schools across the GBR catchment
by offering an endorsed curriculum that provides for outdoor environment based activities and support for on-ground
projects. A pilot for ‘Reef Guardian Farmers and Fishers’ is now being developed with strong government and industry
support.
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Case s tudy 32
Lessons learned and recommendations
The following actions have underpinned the success of the program to improve GBR water quality:
• The World Heritage status of the GBR has facilitated strong financial support for research over the last 30
years and has provided political strength to pursue large-scale management initiatives; this is not available in
other parts of Australia;
• Strong scientific research and monitoring was needed over a long time (more than 20 years) to change public
perceptions that there was a problem from increasing loads of pollutants in runoff coming from catchment
areas;
• More effective management of land-based activities required sound scientific evidence, transparent
communication of scientific research and monitoring results, and partnerships between authorities, industry
and the community;
• Recognition that the social wellbeing of local communities and the Australian economies are significantly
reliant on healthy GBR ecosystems;
• Managers recognised that sediment, nutrient and pesticide pollution reduction was necessary to help
increase the resilience of the GBR to ocean acidification and coral bleaching threats resulting from global
climate change;
• The authorities involved key stakeholders in delivery of ‘Reef Plan’ targets and engaged the public (especially
schools and school communities) in an environmentally based ‘Reef Guardian’ program to raise and maintain
community awareness;
• Engaging agricultural industries to identify the best management practices for improving water quality
outcomes was critical to measure water quality improvements. However the manner in which the
Queensland regulatory regime was introduced to ensure cessation of unacceptable practices led to ongoing
protests by some farming interests, and a more flexible and cooperative approach to the legislation
implementation is now being pursued by the Queensland Government;
• A regular monitoring program has been established to measure the effectiveness of control measures.
This includes water quality monitoring and modelling, remote sensing, and seagrass and coral reef health
assessment. Some aspects of the program engage the community in water quality sample collection; and
• All this required a cooperative effort from all levels of government and NGOs through the provision of a
broad-based planning framework (Reef Plan) with a clear goal and targets, and supported by government
funds to assist industries and communities to make the necessary changes to reduce sediment, nutrient and
pesticide pollution into the GBR. This is backed by strong legislation at all levels of government.
Contacts
Hugh Yorkston, Great Barrier Reef Marine Park Authority, h.yorkston@gbrmpa.gov.au, Jane Waterhouse, Reef and
Rainforest Research Centre, j.waterhouse@c2o.net.au, Jon Brodie, James Cook University, jon.brodie@jcu.edu.au; and
Katharina E. Fabricius, Australian Institute of Marine Science, k.fabricius@aims.gov.au
Recommended Reading
Main review: Brodie J, Binney J, Fabricius K, Gordon I, Hoegh–Guldberg O, Hunter H, O’Reagain P, Pearson R, Quirk M,
Thorburn P, Waterhouse J, Webster I, Wilkinson S (2008). Synthesis of evidence to support the Scientific Consensus
Statement on Water Quality in the Great Barrier Reef. The State of Queensland (Department of Premier and Cabinet)
Brisbane. www.reefplan.qld.gov.au/publications/scientific_consensus_statement.shtm
Environmental studies of specific aspects:
De’ath G, Fabricius KE (2010). Water quality as a regional driver of coral biodiversity and macroalgae on the Great Barrier
Reef. Ecological Applications 20, 840–850.
Fabricius K, Okaji K, De’ath G (2010). Three lines of evidence to link outbreaks of the crown-of-thorns seastar Acanthaster
planci to the release of larval food limitation. Coral Reefs 29, 593-605.
Lewis SE, Brodie JE, Bainbridge ZT, Rohde KW, Davis AM, Masters BL, Maughan M, Devlin MJ, Mueller JF, Schaffelke B
(2009). Herbicides: A new threat to the Great Barrier Reef. Environmental Pollution 157, 2470–2484.
McKergow LA, Prosser IP, Hughes AO, Brodie J (2005). Sources of sediment to the Great Barrier Reef World Heritage Area.
Marine Pollution Bulletin, 51: 200–211. and
Ibid. Regional scale nutrient modelling: exports to the Great Barrier Reef World Heritage Area. Marine Pollution Bulletin,
51: 186–189.
Information on government initiatives
Reef Water Quality Protection Plan - www.reefplan.qld.gov.au
Queensland Great Barrier Reef Protection Amendment Act 2009 www.reefwisefarming.qld.gov.au
‘Reef Guardian initiative’ - www.reefed.edu.au/home/guardians
Great Barrier Reef Water Quality Guidelines www.gbrmpa.gov.au/corp_site/key_issues/water_quality/water_quality_
guidelines
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B
14
20
12
15
10
10
8
5
C
Number of hard coral species
16
25
20
15
10
5
D
0.4
0.6
0.8
1.0
1.2
0.4
0.6
0.8
1.0
1.2
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110
100
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Case s tudy 32
Macroalgae % cover
A
95
90
90
80
85
20
15
10
Secchi depth (m)
5
<----- Clear - - - - - - Turbid ---->
Chlorophyll (µg/L)
<----- Clear - - - - - - Turbid ---->
These graphs show the effects of suspended sediments and nutrients on macroalgae (seaweed) and the diversity of coral communities
on the Great Barrier Reef. The area of reef covered by large fleshy algae (A and B) increases significantly in more dirty water, which also
contains higher concentrations of nitrogen and phosphorus nutrients. Conversely the number of coral species (C and D) growing on the reef
(coral diversity) decreases significantly in more turbid and nutrient rich water.
The X-axes in A and C show Secchi disk depth, a measure of water clarity (the deepest water where a black and white disk is visible). Thus a
site with 20 m Secchi disk depth has very clear water, whereas 5 m is very turbid water. The X-axis on B and D shows the concentration of
chlorophyll a in the water, with higher concentrations occurring where there are more phytoplankton growing because of higher nutrient
concentrations. Thus macroalgal cover increases where there are higher concentrations of phytoplankton, while coral diversity drops
markedly in phytoplankton rich waters. Thus the macroalgae are at a competitive advantage over corals, indicating that the status of
coral reefs on the GBR is clearly related to the quality of water, which is a reflection of the sediment and nutrient loads coming out of river
catchments. The dotted line in all figures is the 10 m Secchi disk depth, and the 0.45 µg L-1 chlorophyll, which are used by the GBRMPA as
water quality guideline trigger values.
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