Pressures affecting marine ecosystems

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Key finding

Sediment, nutrients, chemicals and litter are the major catchment pressures that broadly impact Queensland’s marine environments.

Queensland

Pressures on Queensland's marine environments vary between different regions and are often linked to the types of land uses that occur in the catchment.

Overall, sediment, nutrients and chemicals are the major catchment pressures that broadly impact Queensland’s marine environments, but these vary in their relative importance in different areas.

Plastic rubbish pollution that washes down rivers and into the sea threatens marine biodiversity and birds.

Climate change also impacts aquatic ecosystems, particularly the Great Barrier Reef.

Healthy Waterways South East Queensland report card

The Healthy Waterways Report Card helps us to understand what pressures are affecting ecosystem health in freshwater, estuarine and marine areas. Historic and current poor land management practices have caused substantial erosion in South East Queensland's catchments. Erosion leads to sediment or mud entering waterways which can smother seagrass and reduce water clarity affecting marine habitats. Sediment from diffuse rural and urban sources is the current primary threat affecting marine health. The amount and source of sediment entering waterways annually is dependent on the level of rainfall.

The marine environment is also impacted by nutrients such as from agricultural run-off or in sewage treatment effluent, but a major program of sewage treatment plant upgrades has significantly reduced this pressure over the past 15 years.

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Great Barrier Reef report card

The Great Barrier Reef Report Card helps us to understand the impact we are having in reducing the pressures affecting Reef health by measuring our progress toward Reef Water Quality Protection Plan targets.

Key Great Barrier Reef ecosystems show declining trends in condition due to:

  • continuing poor water quality
  • cumulative impacts of climate change
  • increasing intensity of extreme weather.

Poor water quality from land-based run-off from adjacent catchments is a major cause of the current poor state of many marine ecosystems of the Great Barrier Reef.

Excess nutrients from agricultural fertilisers and fine sediment from erosion of agricultural lands pose the greatest water quality risks to the Great Barrier Reef.

  • Excess nutrients are linked to crown-of-thorns starfish outbreaks which can destroy areas of coral.
  • Excess sediments reduce the light available to seagrass ecosystems and inshore coral reefs and can smother these important marine habitats.

Agricultural chemicals such as pesticides pose a risk to freshwater and some inshore and coastal habitats.

The report card shows that we are making progress toward the Reef Water Quality Protection Plan targets to reduce nutrient, sediment and pesticide loads, however results show the need to accelerate the rate of change to meet the ambitious targets. This will help to reduce pressure on the Reef.

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Fitzroy Basin report card

The Fitzroy region experienced three years of significant wet seasons, then lower than average rainfall for 2013-2014 which reduced river flows and influenced catchment water quality. As a result, drought conditions in the west brought about declines in ground cover. The load of sediment and associated nutrients delivered to the marine zone in record breaking flood plumes of previous years resulted in severe degradation of the receiving marine environments, which have been slow to recover.

Infestations of crown-of-thorns starfish on the Swains Reefs in the Fitzroy region have occurred for the past three decades. These outbreaks of crown-of-thorns starfish are having a continued impact on the density of coral reefs in the region.

In 2010-2011, flows containing excess sediment from the Fitzroy River were the largest on record leading to declines in seagrass. In the Fitzroy region seagrass abundance continues to decline having an ongoing impact on populations of dugongs and turtles.

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Gladstone Harbour report card

All marine zones reported in the 2015 Gladstone Harbour report card received good or very good scores for overall water quality.

Excess levels of nutrients, such as nitrogen and phosphorus, are pressures on marine environments. Scores for nutrients recorded in the 2015 Gladstone Harbour report card were generally low across all marine zone, but did improve from those recorded in the pilot report card. The cause of the poor grade for nutrients requires further investigation. Sediment quality was very good across all sites.

Dissolved metals, such as aluminium, lead, manganese, nickel, zinc and copper measured in the 2015 Gladstone Harbour report card also impact marine environments. Levels of these dissolved metals, with the exception of copper, were found to be consistently very low levels across all marine zones. Generally lower scores for copper Were recorded in all marine zones but were still satisfactory.

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Mackay-Whitsunday report card

Current pressures in the Mackay–Whitsunday region range from those occurring on an international level such as climate change to reef-wide pressures and localised regional pressures among them coastal, port and agricultural development, tourism and litter.

Activities in the catchment strongly influence waterway health scores. Mackay–Whitsunday region is a major agricultural area with a significant area of the catchment under cane production: catchment run-off of pollutants, particularly nutrients and pesticides, presents a major pressure.

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Condamine Catchment report card

Marine ecosystems not analysed in report card publication.

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QCatchment Bulloo

Marine ecosystems not analysed in report card publication.

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QCatchment Paroo

Marine ecosystems not analysed in report card publication.

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QCatchment Warrego

Marine ecosystems not analysed in report card publication.

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QCatchment Nebine

Marine ecosystems not analysed in report card publication.

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QCatchment Wet Tropics

Marine ecosystems not analysed in report card publication.

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QCatchment Lake Eyre

Marine ecosystems not analysed in report card publication.

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Indicator: Pressures identified in report card area

Pressures identified in various water quality report cards across Queensland.