Estuaries are impacted by pressures from human activities as well as natural events such as storms and floods. They are complex, dynamic and relatively fragile environments. Estuaries are particularly sensitive to inappropriate catchment development, increased levels of sediment and nutrients and the degree of tidal flushing – the exchange of fresh water and ocean water.
Common threats to estuaries
The health of estuary ecosystems is threatened by:
- increased nutrients and algal blooms
- loss of habitat and biodiversity
- contaminants and pollutants
- accelerated rates of sedimentation
- disturbance of acid sulfate soils
- changes to freshwater and tidal flows
- invasive species
- climate change.
What we do about threats to estuaries
Monitoring and reporting
We work to manage and protect estuaries. Our scientists conduct research and monitor the health of estuaries. We regularly collect and analyse data on the physical properties of estuaries, including their habitats, biodiversity and water quality.
Identifying risk and threats
We use past surveys to compare with present estuary conditions and we work to identify the major threats to estuaries and the causes of these threats.
To help with monitoring, evaluating and reporting on estuary health, we have developed the Coastal Eutrophication Risk Assessment Tool or CERAT. This tool allows us to identify current threats and probable outcomes and is used to inform land-use planning by local councils.
Causes of threats to estuaries
Population growth and coastal development are two of the key causes of threats to our estuaries.
- Population growth
Over 80% of the population of New South Wales lives in coastal areas, including the shores of estuaries. Much of the northern and central coastline of NSW is far more densely populated and developed than other parts of Australia and is under greater environmental pressure.
Coastal areas attract millions of visitors in summer holidays and estuaries are often the focus of outdoor activities such as recreational fishing and boating, placing additional strain on natural resources and infrastructure.
- Urban coastal development
Urban development has had a negative impact on estuarine environments. Channels have been dredged, wetlands drained, saltmarshes and tidal flats filled, waters polluted, and shorelines reclaimed to accommodate housing, transportation, and agriculture needs.
Overuse of resources and unchecked land use practices have resulted in unsafe water for swimming, oyster harvesting closures, harmful algal blooms, unproductive fisheries, loss of habitat, fish kills, and risk to human health.
Major issues affecting estuaries
Estuary management committees, councils, agencies and the community have identified several issues affecting estuaries including:
- declining estuarine water and sediment quality
- degradation and loss of estuarine habitats
- unsustainable coastal development and use of estuarine resources