Pressures

Many pressures affect wetlands. Some can lead to a loss of wetlands entirely (see: Wetlands—State of the Environment (Pressures Chapter) 2011[1]), others may alter the components and processes of the wetland and affect how it functions, thereby impacting on its biodiversity and values.

Pressures can result from underlying human activities (drivers) including population dynamics, economics, technology and climate.

Pressures on wetlands can occur across a range of scales. Their effect can vary depending on a number of factors including intensity, landscape setting, type of wetland (lacustrine and palustrine, riverine and marine and estuarine), sensitivity of the wetland to the pressure, frequency of the pressure and the management in place to mitigate the impacts.

Pressures affecting wetlands may be located a long way from the wetland itself, e.g. a dam at the top of a catchment may significantly alter the hydrology of a downstream wetland. It is important that wetlands are managed from a whole-of-landscape perspective to help ensure pressures are addressed at appropriate scales.

Direct pressures on wetlands

Direct pressures on wetlands include:

• impacts on water quality through:
  • direct input of contaminants (e.g. nutrients, sediments, metals, pesticides and herbicides, pathogens, litter, excess heat) to wetlands from:
    • stormwater
    • groundwater contamination, e.g. septic systems
    • sewage outfalls
    • agricultural run-off
    • seepage from landfills
    • salinity changes
    • increased water temperature
  • increased sediment suspension
• impacts on wetland soils through:
  • mechanical disturbance of soil which can lead to acid sulphate soils (low pH and metal mobilisation)
  • disturbances and changes to soil structure and nutrients caused by:
    • grazing
    • pest species, e.g. feral pigs, cane toads, carp, tilapia
• impacts on wetland biota through:
  • disturbance or removal of wetland flora and/or fauna
  • influence of pest flora or fauna, e.g. water hyacinth, hymenachne, chinee apple, pigs, carp and others
• impacts on physical form of the wetland from:
  • mechanical changes including changes to hydrology, e.g. draining and filling
• miscellaneous impacts include:
  • inappropriate fire regimes
  • litter or rubbish.

Indirect pressures on wetlands

Indirect pressures on wetlands include:

• catchment disturbance from:
  • land use changes
  • wetland draining or filling
  • vegetation clearing
  • the introduction of sediments and pollutants to the wetland
  • increases in weed and pest animal species
• impacts on the fringing zone of the wetland
• loss of connectivity of the wetland to the overall landscape
• hydrological disturbances including: 
  • the diversion of water from wetlands
  • increased flows of water to wetlands through altered stormwater flows
  • changes to the hydrological water regime of the wetland through water extraction (both surface and groundwater)
  • impoundments.

A changing climate will compound the pressures above. Rising sea levels will effect the landward movement of estuarine wetlands, resulting in pressure on existing freshwater wetlands which have little opportunity to migrate landward. Extreme weather events associated with climate change, including higher temperatures, more intense rainfall and droughts will result in increased pressure on wetland ecosystems.

A landscape hazard assessment for wetlands in the Great Barrier Reef catchment

This report details the approach taken to assess hazards to lacustrine and palustrine wetlands in the Great Barrier Reef (GBR) catchments in Queensland. It provides a landscape scale assessment of hazard (as opposed to fully quantified 'risk') arising from land-use, and is conducted as a desktop GIS analysis.

The 2017 Scientific Consensus Statement for the Great Barrier Reef

The 2017 Scientific Consensus Statement for the Great Barrier Reef is a review of scientific knowledge on water quality issues in the Great Barrier Reef. The statement was produced by a multidisciplinary group of scientists, with oversight from the Reef Independent Science Panel. It arrives at a consensus on the current understanding of the Great Barrier Reef system, and evaluates the ability of current initiatives to meet water quality targets set in the Reef 2050 Water Quality Improvement Plan 2017–2022.

Chapter 1 contains an overview of the state of marine and coastal aquatic ecosystems and the pressures on them.

Additional information

• Fish Habitat Protection Protocol Against Bushfires
• The usefulness of a Threat and Disturbance Categorization Developed for Queensland Wetlands to Environmental Management, Monitoring and Evaluations
• A framework for assessing the health of coastal waters: a trial of the national set of estuarine, coastal and marine indicators in Queensland. June 2007 Final report (condensed version)
• Coastal Zone Estuary and Waterway Management Technical Report 69
• Users' Guide to Estuarine, Coastal and Marine Indicators for Regional NRM Monitoring
• Conservation Measures Partnership

Pages under this section

References

1. ^ a b Department of Environment and Heritage Protection, (2011). State of the Environment Report. [online] Available at: https://www.stateoftheenvironment.des.qld.gov.au/__data/assets/pdf_file/0005/1260617/soe-report-2011.pdf [Accessed 10 October 2012].

Last updated: 22 March 2013