Everyone calls Richard Kingsford Doctor Duck. The nickname is apt because Kingsford really knows his birds: from breeding, feeding, parenting and migrating habits right down to subtle differences in colouring, shape and even the flutter of a tiny wing tip. Given his expertise, it is not surprising that Kingsford works as a biologist with the National Parks and Wildlife Service in Sydney. What is odd about Doctor Duck, however, is his penchant for seeking – and finding – waterbirds in the dusty outback of central Australia.
From the air, the outback of New South Wales appears bleak. The expanse of iron red soil and sparse dull green vegetation stretches from horizon to horizon, broken only by occasional flashes of sunlight glinting from a crusty white saltbed, claypan or a temporary stream or lake left after a flash flood. Details emerge as the pilot puts the Cessna into a stomach-churning dive towards one of these ‘ephemeral’ lakes: scrubby looking lignan and hopbush, a smattering of mulga shrubs and eucalyptus trees, a pair of startled emus and, on the small blue lake, flocks of birds.
When the plane levels at an altitude of 30 metres and begins tracking the perimeter of Lake Altibouka, Kingsford and his colleague John Porter flick on hand-held tape recorders and start counting the birds visible from both sides of the plane: ‘150 pink ears, 3 glossy ibis, 50 little grebe, 20 Pacific heron, 4 black swan, 200 freckled duck . . .’ After a short flight around the lake, the total is staggering: nearly 40 000 birds representing 57 different species on a lake that is just 3 kilometres long. And this lake is just one of the hundreds that dot the landscape. Virtually every one is packed with hundreds or thousands of waterbirds of dozens of species.
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Kingsford has been counting water birds in the outback since 1986. His persistence has revealed a vast ecosystem that supports an astounding abundance of birdlife. To most biologists, Kakadu National Park, in the Northern Territory, is the jewel in the crown of Australian ecosystems: it is home to a third of the country’s bird species. Yet the density of waterfowl in the dusty outback ‘is two to three times greater than in Kakadu and it rivals the flamingo lakes in Africa,’ says Kingsford. Most of the birds live year-round in Australia, but in the autumn hundreds of thousands of little wading birds, including the sharp-tailed sandpiper and the red-necked stint, arrive in the outback after flying south from Russia and China.
The mystery of how a transitory desert wetland could be so biologically productive has aroused the curiosity of a handful of scientists. ‘You can name them on your fingers,’ says Andrew Boulton, an aquatic ecologist at the University of New England in New South Wales. Though their numbers are small, the tiny band is beginning to tease out the components of a complex and ancient ecosystem, a system that has been dismissed as ‘biologically uninteresting’ by researchers who, as Kingsford notes, work ‘huddled along the east coast of Australia’ where working conditions are less arduous.
There is an urgency to their scientific quest. Not only does the water and the life it nurtures appear and disappear suddenly, the entire ecosystem is under threat from encroaching human activity, especially the diversion of water for farming. Erosion and sedimentation caused by vehicles, mining, livestock and feral animals are also rapidly growing threats to the wetlands. So, too, is the gradual expansion into the Lake Eyre basin of highly competitive exotic plants and animals. ‘It is only a matter of time,’ warns Jim Puckridge, an ecologist at the University of Adelaide.
When it comes to desert ecology, scientists are a biased lot, according to Kingsford and the others working in the wetlands of the outback. Most researchers, especially those who trained at universities in the northern hemisphere or who study temperate water systems, overlook the desert wetlands. Yet, nearly half of all inland waters in the world are saline desert systems.
DRY TESTIMONY
Doctor Duck’s wetland is one of scores of similar systems lying within or nearby Australia’s Lake Eyre basin, an internal drainage system covering 1.14 million square kilometres. The basin reaches from Mount Isa, west to Alice Springs, east to the western edge of New South Wales then south to Lake Eyre itself, a giant ephemeral lake in South Australia which filled in 1988 after many years as a crusty dry saltpan. The origins of this vast geological entity go back 200 million years to the time when Australia existed as two huge islands separated by a shallow sea. During subsequent millennia the oceans advanced and retreated over the ancient seabed.
Today, the Lake Eyre basin remains a dry testimony to this watery past. At its highest point, the basin is a mere 230 metres above sea level and at its lowest, 15 metres below sea level. With these gentle gradients, the basin forms an enormous flood plain fed by rain falling over the basin in the north and, erratically, by sudden monsoon-like downpours scattered throughout the region. Annual rainfall in the basin is highly variable. It can range from 400 millimetres in the Queensland area to almost nothing in its dune-covered heart.
When rain does fall it is ‘almost a catastrophic event’, according to Sam Lake, an ecologist at Monash University in Melbourne, Victoria. A single storm may dump more than 70 millimetres of water in a day. ‘So these flood plains don’t just slowly fill,’ he says. ‘Walls of water come down the river. Springs surge. It’s really exciting stuff.’ Water may inundate hundreds of square kilometres of flood plain. As the flood waters abate, they leave behind a mosaic of braided channels, swamps, rivers and fresh and salty lakes which all function, ecologically and hydrologically, as a single unit.
A few ‘terminal’ lakes lying at low points on a flood plain endure for years but most of the water will vanish within weeks or months. Some will evaporate in the summer heat, which averages 36 degreeC to 39 degreeC and frequently hits 50 degreeC, but most goes underground. Boulton estimates that three-quarters of the water in the system at any one time flows below the surface. Depending on the porosity of the soil, he says, the water may travel ‘tens of centimetres or tens of metres’ underground.
Subsurface water either runs into terminal lakes or tops up the water table. When the water table rises to the surface or an underground stream reaches the lowest point in a dry river bed, water wells up to the surface. ‘It’s a paradox,’ Boulton says. ‘Suddenly you find a river beginning to flow where there’s been no rain anywhere nearby.’
Water emerging from deep within the ground carries with it salt deposited by the long-gone seas. The salty water seeps into streams and lakes where it mixes with fresh rainwater. ‘You can get many different chemical combinations,’ says Boulton who points to lakes that are saline on the bottom and fresh on top. As such a lake evaporates, the salinity increases until there is nothing left but a dry saltpan. The saltiest lakes are crystallising brine whereas the freshest contain virtually no salt. Bill Williams, a limnologist at the University of Adelaide, adds that roughly two-thirds of lakes in the basin are saline. Most are also highly alkaline.
Regardless of whether water falls from the sky or rises from the earth, as soon as it hits the dry flood plains of the Lake Eyre basin, life explodes. Biting midges and water fleas, mosquitoes, water bugs and beetles, along with tiny invertebrates such as copepods and fairy shrimp hatch overnight.
Boulton has found that by adding distilled water to a sample of dried flood plain just 20 centimetres square, a ‘rich soup’ of ‘tens of hundreds of invertebrates’ hatches. Brian Timms, a limnologist at the University of Newcastle in New South Wales, has identified 74 species of invertebrates at Paroo, a desert wetland lying just outside the Lake Eyre basin. Shrimp and copepods were the most abundant animals. The wetlands are also home to hardy snails and frogs. Fish such as the bony herring live in semipermanent lakes and streams.
FRENZY OF BREEDING
With the advent of water, plants appear in what were previously dry saltpans, riverbeds and claypans. Blue-green algae and other microscopic phytoplankton spring up in all but the most salty lakes. Reedy underwater grasses such as ruppia thrive in salt lakes, as does the millfoil with its mats of brownish red flowers. Similarly, cane grass and the yellow-flowered water primrose flourish in freshwater lakes and ponds.
Within days the first birds – following unknown clues – fly in to feast on the invertebrates which, in turn, eat smaller creatures and phytoplankton. A frenzy of reproduction begins, as each species makes the most of the favourable conditions. According to Puckridge, most creatures continue to breed as long as good conditions hold, slowing only in the middle of winter.
This pulse of life is possible because the plants and animals have adapted their life cycles to the extreme and unpredictable conditions of the outback. For instance copepods, shrimp, water fleas and other invertebrates lay eggs which resist dehydration. Researchers are only beginning to find out the secrets of these tough eggs, yet some patterns are emerging. Wetland scientists believe that some creatures lay two kinds of eggs: one type during dry conditions and another in the wet. Other animals may produce eggs that halt development at specific stages of incubation, ranging from a very young stage to almost adult. How they do it is unclear, but whatever the trick the egg does not hatch until it detects water.
The water-holding frog stores water in its bladder and burrows underground. There it builds a watertight chamber where it can live for many years. The freshwater snail survives prolonged drought in a dormant state, nestled among plant roots and debris. Birds follow the water rather than rigid migration patterns.
Fish, too, have unusual survival strategies. Although they clearly cannot live without some water, bony herring, for example, rapidly disperse over the flood plains at the slightest hint of water, even a few centimetres deep. Many die if the water peters out or evaporates, but some make it to semipermanent lakes and streams where they will lay their eggs. And plants produce seeds or vegetative bodies that resist dehydration and salt. All the organisms are ‘primed and waiting’ for water, concludes Lake.
Not only do creatures of the wetlands need water, they need it in giant gulps. ‘Floods serve as cues for things to hatch out,’ notes Boulton. He fears that if flooding in the Lake Eyre basin is controlled by weirs and dams, or if water is drained from terminal lakes and streams for the benefit of water-hungry farmers and graziers, many wetland animals will ‘go extinct’.
Yet already farmers in Queensland are taking ever-increasing amounts of water from the headwaters of rivers that feed the Lake Eyre basin to support the lucrative cotton industry. Moreover, a rising demand for drinking and irrigation water in southeast Australia is putting pressure on the Murray and Darling rivers. At present, these two rivers supply most of the water for this area, the fastest-growing and most densely populated part of Australia.
Puckridge predicts that the water boards will inevitably turn their attention inland to the Lake Eyre basin, the only other source of readily available water. He claims that researchers have no idea how much water can be removed from the basin before the ecosystem begins to break down. ‘It’s a fallacy to assume that you can use some water without causing ecological damage,’ he warns. ‘All the water that flows in the rivers is used ecologically.’
WEAR AND TEAR
Outback wetlands also suffer wear and tear from cattle as graziers, particularly in the Coongie Lakes wetland in South Australia, truck their stock from one ephemeral lake to another. Not only do the animals drink the precious water, they trample the banks. The dirt that falls into the water makes it turbid and reduces the amount of sunlight reaching the lower depths. This hampers the production of algae, which is urgently needed by the newly hatched animals to feed on. Erosion is a problem everywhere in the basin, with loss of topsoil aggravated by feral foxes, cats and rabbits as well as miners and tourists who roam the outback in four-wheel drive vehicles.
Exotic species also threaten to upset the delicate ecological balance of the basin. In the late 1980s, for example, state officials in Queensland and South Australia introduced the Murray cod, popular with anglers, into the Cooper and Thomson river systems, where it outcompetes native fish for food. Meanwhile, another potentially destructive invader, the athel tree, is spreading unchecked along the Finke river of the Northern Territory. The athel is renowned for its deep-ranging roots and its ability to withstand drought and salinity. Eventually its roots displace those of native trees, which may then be washed away in flood waters.
It is not just the threat to this fragile ecosystem that exasperates the wetland scientists; they also fear that the ecosystem will become seriously damaged before it is understood scientifically. This knowledge, they say, is vital to efforts to protect and manage the Lake Eyre basin.
Many of the existing threats to the outback wetlands are borne of indifference. According to Williams, Australians traditionally have viewed these areas as ‘wastelands’. Attitudes among scientists from temperate zones have done little to alter this perception. ‘The rivers in the Lake Eyre basin haven’t even been considered rivers,’ claims Puckridge. ‘Because they don’t flow continuously like a European river, they aren’t considered rivers. They are just places where you can or can’t water cattle. Even the maps are bloody lousy for these river systems.’
In 1974 Australia became the first signatory to the Ramsar Convention, an agreement that obliges members to protect wetlands of international significance. Twenty years on, 42 Ramsar sites have been listed in Australia, but only one in the Lake Eyre basin – the Coongie Lakes system, which the government agreed to include in 1987 because of its importance to migratory birds.
Individual states have created, in an ad hoc fashion, 46 nature conservation reserves in the outback wetlands. But these cover just 8 per cent of the basin, and are not ecologically representative.
Jurisdictional squabbles between the state and federal governments and heated infighting between pastoral, mining, environmental and Aboriginal interests have also hampered the search for a sound management structure for the Lake Eyre basin. ‘Attempts to develop a cooperative arrangement over the Lake Eyre basin rivers have barely begun,’ notes Puckridge.
The result is a patchwork of uncoordinated legislation. Key federal acts cover pastoral land management, parks and wildlife, mining, soil and water conservation. These acts are mirrored by a tangle of rules and regulations in Queensland, New South Wales, South Australia and the Northern Territory. The end result is confusion, confrontation and fragmentation of management.
The Australian Nature Conservation Agency, the country’s main environmental body, is taking a softly, softly approach. Since 1992 the agency, under the leadership of biologist Peter Bridgewater, has been quietly laying the scientific groundwork for a ‘desert river strategy’ aimed at bringing the warring factions together into a single basin-wide management scheme. Bill Phillips, director of the ANCA Landscape Conservation Unit, explains: ‘It is a biosphere reserve model. You identify the jewels in the crown, the necessary buffer zones and a zone of cooperation.’
Phillips is optimistic a workable strategy will emerge. Over the past two years, key government organisations, including ANCA and state environmental agencies, have put together the building blocks of a total catchment management system for the Lake Eyre basin. Such a system will treat the basin as a single ecosystem, rather than as disconnected chunks. Decisions will be made with the wellbeing of the entire wetland system paramount, rather than the interests of individual governments. ‘It would be a tragedy if it was allowed to die,’ says Phillips.
Puckridge agrees but argues that all development – whether mining, agriculture, grazing, ecotourism or the diversion of water – should be halted now. ‘If you look at river systems around the world you realise that these systems are absolutely precious,’ he says. ‘Surely we can afford to leave them as examples of relatively pristine systems. God knows there are few enough left in the world.’