Unfortunately, many of the 40 estuaries in South West Western Australia are in poor or declining health. The most immediate and direct human impact is eutrophication, where the oversupply of nutrients causes an excessive growth of plants and algae, pushing the ecosystem out of balance. The Regional Estuaries Initiative aims to improve health in six of the most at-risk regional estuaries – the Peel-Harvey, Leschenault, Vasse-Wonnerup, Hardy Inlet, Wilson Inlet and Oyster Harbour.
These water bodies have cultural and spiritual values, particularly for our Aboriginal population for whom these water bodies are nurturing, life-sustaining, sacred and integrally intertwined with their being. These areas are sanctuaries within but also removed from the frenetic, fast-paced urban lifestyles. Estuaries are also highly valued for natural open space, aesthetic qualities, tranquillity and peacefulness:
- the tranquillity and peacefulness make them desirable places to live and people are willing to pay a premium to live near the water
- they provide a wide range of recreation opportunities – swimming, boating, fishing, crabbing, walking, cycling, kayaking, stand-up paddle boarding, kite surfing, bird watching, picnics and barbeques.
Unique environments and important habitats
These partially-enclosed water bodies form transition zones between river and marine environments. Estuaries are influenced by the land and by the sea – with freshwater flow carrying sediments and nutrients, and tidal exchanges of seawater respectively. They are naturally dynamic environments.
Estuaries are among the most fertile and productive environments in the world. Their diverse range of physical habitats support a wide array of plant and animal communities by providing:
- permanent habitat for many species
- spawning grounds and nurseries for juveniles
- dispersal corridors
- migratory stopovers for birdlife.
Strong economies: trade, tourism, fisheries and natural infrastructure
Estuaries provide critical services to the long-term wellbeing of all Western Australians, but their capacity to sustain these services is dependent on their physical condition and ecological health. For our regions to grow and reach their economic potential, we must also support good health of our estuaries.
Estuaries also provide a number of economic benefits we often take for granted, such as:
- protection of shorelines and infrastructure from storm surges and floods
- natural treatment of pollution discharged from industrial, agricultural and urban activities.
Our engineering legacy
Our estuaries and their catchments have undergone rapid change over the last century or so. The ability of our estuaries to absorb these pressures has reduced over time, as the cumulative impact increases. We now need careful and active management to ensure values are sustained whilst enabling economic development and liveability of our estuaries.
Estuaries are influenced by a multitude of stressors:
- extensive drainage network has lowered the water table, draining wetlands and disconnecting related water bodies to facilitate agriculture in our catchments
- fresh water flow volumes have reduced due to water use for irrigation, industry and urban water supply
- diversion of natural flows for flood control
- increased sedimentation from land clearing, soil erosion and overgrazing
- increased pollutant and nutrient load from industrial, agricultural and urban waste
- loss of estuarine foreshore from hard-walling and canal developments
- overfishing, habitat destruction and the introduction of foreign species
- altered freshwater flow regimes from climate change – our estuaries are becoming more marine, and a shift in species distributions has been observed.