By Pat Pepper, NCWQ Environmental Adviser
This report focusses on water quality in the Great Barrier Reef (GBR).
As noted in the Position Statement by the Great Barrier Reef Marine Park Authority (GBRMPA), pollutants in land-based run-off are a major threat to water quality of the GBR and particularly inshore marine ecosystems and consequently to the long-term health and resilience of the GBR.
Resilience is paramount if the predicted increased frequency of marine heatwaves and the intensity of rainfall events and cyclones are to be combated. While the Reef Water Quality Report Card 2019 showed encouraging progress being made towards achieving the targets in some areas, more action is required across all GBR catchments to continue to drive progress towards all the targets. Hopefully, this will be achieved as projects under the Reef Trust Partnership, aimed at improving the quality of water entering the GBR through activities such as improved farming practices, reduced fertiliser use and update of new technology, gain momentum.
Another issue for the corals was highlighted in recent research on population sizes of more than 300 individual species on reefs spanning the Pacific Ocean. While most reef-building coral species were not in imminent danger of extinction, the researchers at ARC Centre of Excellence for Coral Reef Studies, James Cook University (Coral CoE at JCU) reported that about a third do face some degree of extinction risk but the International Union for Conservation of Nature (IUCN) Red List of Threatened Species had some corals misclassified.
Position Statement by the GBRMPA
The main water quality pollutants include fine sediment, excess nutrients, pesticides (herbicides, insecticides and fungicides) primarily from agricultural activities in the catchment. Although other land-based developments such as urban and industrial areas, mines and ports, can contribute at some locations with pollutants such as coal dust, petroleum hydrocarbons, heavy metals, marine debris and microplastics, pharmaceuticals and personal care products. Fine sediment in the water reducing the amount of light available, can affect the growth and reproduction of grass meadows and inshore coral reefs. Excess nutrients have been linked to blooms of harmful algae and may exacerbate outbreaks of coral-eating crown-of-thorns starfish, coral bleaching and disease. Pesticides used on crops to protect against pests may also affect marine plants and animals, reducing the resilience of nearshore marine habitats. To support a healthy reef ecosystem, the GBRMPA has set limits for levels of sediments, nutrients and pesticides in marine waters. GBRMPA Document No: 100516 Revision: 0 Date: 27-Oct-2020
The Reef Water Quality Report Card 2019 released 17 February2021, showed a 4.3% modelled reduction in dissolved inorganic nitrogen (DIN) loads across the GBR catchments, with the greatest reductions in the Wet Tropics (7.4%) and Burdekin (4.5%) regions. The majority of the load reductions were credited to the adoption of practices that reduced the nitrogen surplus in sugarcane. Banana projects in the Wet Tropics also contributed to the reduction. This represents a cumulative reduction of 25.5% since 2013. The 2025 target is 60%.
Cape York has met its 5% sediment reduction target since 2016 with further reductions in 2018-2019 of 0.3% contributing to an overall reduction of 10.1%. These reductions were attributed to improvements made in the Normanby catchment. Burnett Mary graziers also contributed significantly to the sediment 2025 target of 20% with a 1.3% modelled reduction due to investment in fencing to exclude cattle from waterways. This brings the reduction to date to 5.6%.
The pesticide target to protect at least 99% of aquatic species is being met in the Kolan catchment (Burnett Mary region). The Pioneer catchment (Mackay Whitsunday region) recorded the greatest improvement in pesticides (up 4.5%) with 80.5% of aquatic species protected from their harmful effects.
While the above results show encouraging progress is being made towards achieving the targets in some areas, more action is required across all GBR catchments to continue to drive progress towards all the targets. https://reportcard.reefplan.qld.gov.au/; https://www.reefplan.qld.gov.au/__data/assets/pdf_file/0025/227068/report-card-2019-summary.pdf
Reef Trust Partnership
Priority catchments and targets for reducing pollution from catchments flowing to the GBR were identified in the Reef 2050 Water Quality Improvement Plan. Under the Reef Trust Partnership, funding of $140.9 million has been committed to a series of regional water quality programs that aim to directly reduce nitrogen (456 tonnes of dissolved inorganic nitrogen (DIN)), fine sediment (462 kilotonnes) and pesticides (250 kilogram) loads from priority GBR catchments (End of Partnership Targets). These programs will focus on proven, on-ground measures for improving water quality, including through catchment restoration and improved land management practices. https://www.barrierreef.org/what-we-do/reef-trust-partnership/water-quality-improvement/regional-actions
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