Preserving our wetlands

As the world focuses on pressing environmental issues such as climate change, there is a risk that other priorities such as the preservation of wetlands may be overlooked by the general public.

Wetlands is essentially an umbrella term for a wide variety of inland and coastal water features. As places where terrestrial and aquatic ecosystems meet, they are home to a high level of biodiversity, most spectacularly encountered when flooding rains bring large breeding flocks of birds, often waders, ducks, and pelicans. Some Australian wetlands serve as stopover points for migratory birds that have flown vast distances from breeding grounds in Siberia, North Asia and inside the Arctic Circle.

Estuarine wetlands, also known as tidal wetlands, are often home to saltmarsh and mangrove vegetation. Occupying a brackish zone where salt and fresh water flow together, they provide a particularly important habitat for fish and birds. In a sense, they are a type of fish nursery where species such as mullet grow up before later migrating to the ocean.

For humankind, wetlands offer a fresh water supply, better sanitation and a more varied diet. Communities such as Leeton in New South Wales, whose wetlands include Fivebough and Tuckerbill, can boost their economies by providing ecotourist activities for walkers and birdwatchers. Viewed from a broader perspective, wetland areas offer an impressive range of environmental benefits. Often located near important rivers, they filter out pollutants and surplus nutrients from the water and have been described as the kidneys of river systems. When there has been heavy rain, they mitigate flooding of neighbouring ecosystems and protect against erosion.

In 2007, Dr Carmel Schmidt at the University of Adelaide carried out a study based on wetlands adjoining the River Murray and estimated the water filtration they offer is worth $7100 per hectare. Where wetlands have been destroyed, the solution has often been to build in their place expensive water treatment facilities with ongoing running costs.

A history of wetland loss

Sadly, wetlands have traditionally had a bad image and were often perceived as little more than breeding grounds for mosquitos that spread diseases to nearby villages. Historically, around the world large areas of wetland have made way for agriculture, industry and human settlement. Perhaps the most extensive example involves the loss of the enormous floodplains of South-East Asia when they were converted to rice-growing paddy fields.

Other wetland areas became degraded as human impact impaired their ability to maintain various natural functions. The removal of vegetation results in fewer habitats for fauna and reduces a wetland’s capacity to protect against salinity and erosion. Agricultural chemicals such as fertilisers and pesticides may harm plant and bird communities. An excess of nutrients can lead to toxic algal blooms, which may cause fish to die from a lack of dissolved oxygen in the water.

In recent decades, three under-reported large-scale wetland disasters have been occurring in different corners of the planet. Fortunately, in each case there are some grounds for cautious optimism.

Rainforest-covered peat swamp found on the island of Borneo is being destroyed to make way for Indonesian and Malaysian palm oil plantations and the process is accelerating. This loss is a major contributor to climate change through forest burning (CO2) as well as via the decomposition of organic matter (methane). An activist group called Wetlands International is working on several projects to help protect the island’s remaining peat swamp forests.

In Central Asia, two large rivers known as Amu Darya and Syr Darya were harnessed during the Soviet era for large-scale irrigated cotton programs in Uzbekistan and Kazakhstan. In addition to drying up the Aral Sea, this has caused many wetlands that formerly existed in the deltas of both rivers to disappear. Current rehabilitation work is focused on important wetlands that surround Lake Sudoche in the Amu Darya delta, a staging ground for endangered migratory birds.

Satellite photos taken in the early 1990s showed that Saddam Hussein was draining the renowned marshes of southern Iraq. This area, which lies between the Tigris and Euphrates rivers, was once known as Mesopotamia and may have been the location of the Garden of Eden. Iraqis living in the US formed an NGO called Eden Again and, since the 2003 invasion, rehabilitation work has been continuing in spite of the many security issues. Today the marshes are steadily recovering.

The agreement at Ramsar

During the 1960s, when the need to halt wetland loss at a global level was recognised, discussions began at the United Nations, culminating in the 1971 Ramsar Convention. It has received widespread international support and, as of March 2008, a total of 158 countries had signed. Criteria determining whether a particular wetland is eligible for Ramsar listing include the site’s zoology, botany, ecology and importance to waterbirds.

As an early signatory, Australia is committed under the agreement to protect its Ramsar-listed wetlands and a set of management principles is set out under the Environment Protection and Biodiversity Conservation Act 1999. In total, 65 wetlands come under Ramsar and are managed by either state or commonwealth authorities. More are being slowly added on a continuing basis, the most recent being the Paroo River Wetlands in northwest NSW last year.

Lake Wollumboola on the south coast of South Australia is an important drought refuge for waterbirds and the National Parks and Wildlife Service is lobbying for it to become another Ramsar site. Meanwhile, the Queensland government is moving to protect the Halifax Bay coastal wetland, located near Ingham, as a National Park. This area plays an important role in protecting the Great Barrier Reef by filtering nutrient-dense runoff, preventing it from spreading out to sea.

Australia’s wetland challenges

Where wetlands are concerned, Australia has a poor history. Although it is very difficult to obtain an exact figure, one study estimates approximately 50 per cent have been degraded or destroyed since European settlement. Only in the decades since Ramsar has their importance been fully recognised, causing government policies to switch towards protection. A similar change in attitude has occurred across most other Western countries.

In northern parts of Australia, climate change is one of the most serious wetland threats. Tidal creek systems are expected to extend further inland, invading freshwater wetlands such as those adjacent to the Mary River in the Northern Territory. These incursions are exacerbated when protective tidal banks are trampled by buffalo and cattle. Other challenges for tropical zone wetlands include the threat of being choked by introduced plants such as salvania, mimosa and para grass.

Another difficulty for some wetland areas adjacent to floodplains is the prevalence of acid sulphate soils. Following a change in drainage activity, some soils with a high ferrous sulphide content can become oxidised and chemically react to form sulphuric acid. Being toxic to life, acid sulphate runoff has been implicated in fish kills and plant loss, but fortunately it can be prevented through soil remediation works.

The Gwydir Wetlands in northwest NSW are an important breeding centre for waterbirds and are protected under the Ramsar Convention. Last year, a farmer cleared hundreds of hectares of wetland on his land adjacent to Gwydir, outraging environmentalists who believe the cleared area may take decades to fully recover. He was recently called to appear in the NSW Land and Environment Court.

In the Murray Darling basin

Covering a large swathe of south-eastern Australia, the Murray Darling Basin is home to many of Australia’s important inland wetlands. Unfortunately, the effects of the continuing drought and water competition with irrigators have been putting pressure on these special places; a drying wetland is also a dying one. Last year, an aerial survey carried out by the University of NSW in partnership with state conservation bodies found that waterbirds were virtually absent from the Basin.

Over the past year, particular attention has been directed at the Macquarie Marshes in central western NSW, not far from Dubbo and Orange. This Ramsar-listed area has greater bird diversity than Kakadu in the Northern Territory and is an important breeding ground for both ibis and egrets. Over recent years, salinity levels have been increasing and the northern part of the Marshes has been drying out.

According to wetland experts Celine Steinfeld and Richard Kingsford, the problem comes down to water demand from agriculture, particularly the cotton industry. In a report released earlier this year, the pair conclude that inappropriate agricultural development has been stealing water from the marshes for decades, aided by government inaction. Kingsford sees governments maintaining an old-fashioned focus on water extraction from rivers while subjecting diversion from nearby floodplains to few regulations or restrictions.

Steinfeld and Kingsford used a combination of satellite photos and helicopter reconnaissance to identify about 2300 kilometres of levees and channels for diverting water, 400 kilometres of which are unapproved. Kingsford believes that unless floodplain harvesting is addressed, strategies based on increasing environmental flows to the Marshes will ultimately be a waste of time because the water will be appropriated in the next dry year.

More encouragingly, by February this year, water from the January floods in the Queensland towns of Emerald and Charleville had reached wetlands in Western Queensland and NSW. This led to the first good environmental flow in the Macquarie Marshes since the year 2000, and hundreds of thousands of birds made a beeline there. However, this respite is not a solution to the underlying water diversion problems.

While this floodwater has made a noticeable difference in the upper part of the Basin, it has failed to reach further downstream. Ongoing drought conditions in the lower Murray have spelled bad news for the river wetland forest with its Murray redgums. A recent estimate indicates that three quarters of all river redgums along the lower Murray are either dead or in ill-health due to a combination of salinity and water scarcity.

The Ramsar-listed Coorong, a large wetland at the mouth of the Murray, and the neighbouring Murray Lakes are all under threat from rising salinity and acid sulphate. According to the Coorong and Lower Lakes Infrastructure Group, the Federal Government needs to purchase a total of 200 gigalitres of irrigators’ water allocations in order to keep salinity and nutrient levels in check.

Belatedly, both state and federal governments have committed to audit development on the Macquarie floodplain and have purchased a significant water allocation from irrigators in the area. A further $50 million has been earmarked for buying back water allocations for environmental flows along the Murray. Only time will tell whether this is sufficient.