Something in the Eyre

Lake Eyre floods. The Australian Magazine, May 20- 21, 2000

Just add water

Record rains have reach Lake Eyre, swelling this vast, dry saltpan into a teeming ocean of life forms – many of which scientist are identifying for the first time.

Story: Åsa Wahlquist

In country where mirages of water shimmer and tantalize on the horizon, the waters of Lake Eyre are the colour of the earth, distinguished from the land only by the rim of salt and greenery, and the chop raised on the water by the desert wind. Lake Eyre lies adjacent to three deserts. It is reached by crossing gibber plains strewn with close-packed tiny glinting rocks so black it looks an inferno has passed by. The sparse vegetation is dominated by low ferocious plants, spiny and prickled, with tough salty leaves, or no real leaves at all.

Hundreds of miles from the ocean, the Lake can harbour water nine times as salty as seawater. When it fills, as it has done only twice in the past century, in 1950 and 1974, it becomes for the duration the biggest lake in Australia, so large it is affected by the gravitational pull of the moon, and experiences tides. Marine birds – pelicans, silver gulls, banded stilts, dotterels and terns – flock to its shores.

The rivers of the Lake Eyre Basin are some of the last wild, unregulated large rivers in the world. Australia has the most variable climate in the world, and in the Lake Eyre region that variability reaches its zenith. It is a place of boom and bust unlike any other on the planet. Only recently have scientists begun to study its myriad life forms, their unique dynamics and processes. There is so much they do not know.

Dr Jim Puckridge, from the Department of Environmental Biology at the University of Adelaide, went on a scientific expedition to several of the rivers that flow into Lake Eyre in April. He says the rivers of the basin are the most variable large rivers in the world. "They are variable in a whole lot of different respects and variable over a whole lot of different time scales. Not just the volume of flow but the frequency, the timing, the shape of the flow pulse. In the past it has been difficult for Europeans to appreciate that they were rivers at all. They so often become discontinuous, they become isolated into waterholes and lakes. The fact that the Cooper was called a creek by Sturt when he first encountered it is an illustration of that gap in perception.

"For Sturt obviously a river meant something like the Thames or the Rhine or the Danube, something that had a continuously flowing channel. These rivers don't behave like that, but they can flow with enormous volumes as big as the Nile, but only intermittently."

If Australia's first settlers had a dreaming, it was of water, of an inland sea that would green the land, provide abundant food, support a population.

The first explorer to see the lake, Edward Eyre, reported "with bitter feelings of disappointment I turned from the dry and cheerless scene around me". A later explorer, Major Warburton returned with an account of land that was "dry, terrible in its death-like stillness and the vast expanse of its unbroken sterility".

What they did not know was that before them lay a system that, with the arrival of water, experiences a massive explosion of life, dwarfing that of gentler, more predictable climes. "The biological production you get in time of flood is enormous," Puckridge explains. "You get nutrients accumulating in dead plant matter over perhaps a decade, so when water comes in there is a huge bloom of life, whereas in a permanent river that is ticking over all the time you don't get that huge cycle of production. It's boom and bust."

Lake Eyre when dry is surely the most inhospitable place on earth. But every five years or so, perhaps ten, enough rain falls in the Lake's 1.2 million square kilometre catchment to deliver water to the Lake.

In February this year, persistent monsoonal rains dumped record rainfalls in western Queensland, New South Wales, and south west Northern Territory. The water began a slow journey through the braided rivers of the channel country in western Queensland, through the wetlands to the north of Lake Eyre, down a gentle gradient to the lowest point in Australia, Lake Eyre.

Ecologist, Dr John Read, manages 12,000 square kilometres of land owned by WMC Resources, including Stuart Creek Station, on the edge of Lake Eyre South.

"We've just had a really, really bad drought. A lot of long-lived perennial shrubs have been dying, and some animals like sleepy lizards and kangaroos that are normally really drought tolerant have been keeling over. But now since the February rains the country has really responded."

The response was immediate. As the rain fell, ants and termites began swarming. Water-holding frogs and trilling frogs, which burrow down and form a cocoon where they can survive several years, emerge.

"Almost as soon as it rains you get birds like crimson chats and orange chats," Read says. "Then once the grasses start seeding, you get big flocks of birds like budgies and cockatiel."

And then there were the insect plagues. "We've had plagues of stink beetles, plagues of grasshoppers, plagues of moths coming through. We are talking about billions of these things. They will plague for a week or two and they will disappear, and something else will come, they come in waves of different critters."

And then there are the flies, "mobs and mobs and mobs of flies," Read says.

Walking through the saltbush with his unselfconscious long-legged stride, Read names grasses and birds with the enthusiasm of someone who has just discovered

them, rather than as the 12 year veteran of the area he is. He point out a black shouldered kite hovering, the call of a Horsfield's bronze cuckoo, a chatter of budgerigars, the high piping song of the pied honeyeater.

"There are lots of birds feeding on the seeds of the grasses and the insects. After a while birds of prey, like harriers and kites, start turning up. I suspect it takes a bit longer, but some of the native mammals and reptiles will start responding to those insects. It is a wave of benefits that sometimes can extend for two or three or even 10 years. You can still see some of the plants that regenerated in 1989, after those big rains. I guess this may be another benchmark and there will be a whole lot of recruitment of plants and birds."

One of Lake Eyre's great mysteries is how do the birds know when to visit? How do different species so precisely time their arrival, to coincide with the brine shrimp hatching, a big fish population, or the flowering of the plant species they prefer, when arriving too early would certainly mean starvation?

"They have an uncanny knack of knowing where the rains have fallen and where the food supplies are," Read says. "There are a number of different theories. Birds that turn up straight after rain are quite possibly following low air pressures or maybe the smell of rain. Some of the birds that turn up weeks after rain, they can't follow any meteorological cues. Pied honeyeaters might turn up several months after the rain, when eremophilas are flowering. Some of the birds like cormorants and pelicans often turn up months, in some cases up to a year, after rain. It is really quite fantastic."

Last year Stuart Creek did not flow at all. Earlier this year, after rain, it spread in a raging flood across the floodplain, "Very few people see it, you can't get in unless you are here when it rains. It would be a pretty awesome experience," Read says.

Brine shrimp hatched, as did shield shrimp which had survived the dry as eggs as small as a grain of sand. For most, there is precious little time to breed: the shield shrimp has a couple of weeks, the trilling frog perhaps three or four weeks, the water-holding frog six.

The waters washed the creek fish – the spangled perch, the Lake Eyre hardyheads, the desert gobys – down into the Lake, where they had to survive first the flood of freshwater, then the increasing saline water of Lake Eyre as the salt dissolved.

"They try to swim upstream and find a permanent waterhole. They might swim up another creek, and mix the gene pool," Read explains. Then, as the creeks dry, the struggle for life will intensify even more dramatically, with tadpoles eating shield shrimps, fish eating frogs, and egrets and cranes picking off the fish, which will end up in huge concentrations in a few waterholes.

Environmental consultant, Frank Badman, points out plants have two different forms of survival. "One is what the perennial plants do. They are very deep rooted and a lot live in areas where they receive additional water, in the gilgais (little depressions in the gibber) and the creeklines.

"The other way is evading the droughts, and that's what the annuals and ephemerals do. They produce huge amounts of seeds in the good seasons, and then the seeds remain viable in the soil for quite a while. They produce huge amounts of seed, because lots of things, ants and various other animals, eat those seeds."

Badman says the late summer and autumn rains produced grasses, but if it keeps raining, in late winter there will be spectacular wildflowers. There will be some scientific finds among them. "I've collected eight or 10 things that are unknown to science," he says. "There is so much country up there, and so few people looking at it."

Retired botanist David Symon, says several years ago they found a native tobacco that had only been collected once before: "And there it was after a good season, hundreds of plants as big as silver beet. It must spend many, many years between these events as seed, and one has just got to be there at the right time to find it."

Another extraordinary find was Typhonium, a member of the arum lily family. "It was only first discovered three or four years ago. Again, this is a plant that is obviously able to survive long periods of drought, and I am not quite sure how it does it. Then, when it does rain, it grows into quite a conspicuous plant. The leaves are almost as big as the white arum lily, it is just incredible that it hasn't been seen and collected before. It's a livery purple flower, but we still know so little about it.

"The last time we were up there, we brought back a chenopod, one of the little prickly sclerolaenas (bindyi) and maireanas (bluebush) which we haven't identified," Symon says. "I am quite sure that there are others there. You have really got to be up there at the right time and to some extent know what you are looking for."

Puckridge says serious biological research into the area only commenced in the 1980s. "The interesting thing for a scientist is how plants and animals cope with this extreme environment. There is a whole range of strategies. For example river red gums seem to manage by being extremely long lived, sending down very deep roots into groundwater, having a kind of endurance strategy, being able to span those intervals of drought

"Some animals do similar things, they have drought resistant eggs. Like shield shrimps, the classic example. Others have extremely flexible life histories so they respond to any kind of pulse of water, even though often that response ends in total mortality, it still seems to be worth their gambling in that way. In contrast with the red gum strategy it is a throw of the dice kind of strategy.

"You get huge mortalities of fish, notably in Lake Eyre itself (like) bony herring and the Lake Eyre hardyhead. These and other fish migrate enormous distances on the flood waters and very often are stranded and die, but evidently in evolutionary time it is a strategy that works. Perhaps one time in decade they get through to another river system, on a big flood and form a new colony and multiply."

The rain also produces some novel experiences: "We had water flooding across the Birdsville track and there were fish streaming across the track in a few inches of water," Puckridge reports.

"It's a real lottery in where they end up. And the densities of animals in those waterholes can be quite phenomenal. You wade through them, fish are bumping into you. I've walked out of water and found a live fish in my pocket, so it is an amazing density."

On his recent field trip, Puckridge found fish in the western rivers near Oodnadatta "had been breeding copiously, there were thousands of larval fish, like tiny little splinters of glass in the water, whereas in Goyders lagoon on the Diamantina River further east, the response had only just begun."

Fish breeding, like so much else in the region, is highly variable, "there's a lot of variability between different species. Every flood had a different pace and a different volume and fish responses vary accordingly. I have never seen fish breeding in late April like that, so I am still learning how flexible they can be."

And how aggressive, "some of the fish we caught in the nets had been eating other fish in the nets, they were very opportunistic." Puckridge suggests such ferocity is the result of a narrow and unpredictable window of opportunity.

Puckridge's trip was the first of half a dozen planned for the next two years, in a project called Aridflo, funded by Environment Australia, and administered by the SA Water Department of Water Resources. Water Policy officer, Michael Good says "the whole purpose of this project is to develop a model of the relationships between flows in these arid zone rivers, and the ecological responses so that people can start to understand those relationships and answer 'what if' questions, like 'what if we extract this amount of water at this time, what is the likely biological response?'"

Plans to irrigate along Cooper Creek, which were subject to heated debate, are currently on hold. "Some of the concerns about the proposal were that we didn't understand the possible implications of that," Good says.

Any future proposal will come under the Lake Eyre Basin Agreement, which is currently being negotiated.

The cloud that hangs over every decisionmaker is the catastophic state of much of the Murray Darling Basin, which is so saline the future of Adelaide's drinking water is under threat.

Good says they are also interested in tapping into the knowledge base of local pastoralists, "they are making a living in a boom and bust environment, just like all these plants and animals are".

Gordon Litchfield, together with his wife Lyn, and his brother and sister-in-law, Peter and Janine, run two properties at Marree, Wilpoorinna and Mundowdna.

"Last year was terrible, one of the worst years in 40 odd years we've been here. We destocked a real lot, about 60 per cent," Litchfield says.

"We've had good rains this year. There is plenty of fodder and feed for the sheep and cattle we've got. A lot of the bush was knocked around a bit, it will all recover, no worries. People call this fragile county, but it's not fragile country, it's bloody tough country, it's incredible what it has survived."

Stock that was sent away on agistment to Victoria is now back. Litchfield says the country could support many more stock, but they are limited by the high cost of cattle, and the maximum stocking rate, set by the Pastoral Board.

"You have to have patience, and be prepared to hang in there for a long time," he says.

"When it is good it is incredible. When it is dry, it can be shocking."

This year will also be different, thanks to the effectiveness of Rabbit Calicivirus Disease. "We've had re-growth in mulga," Litchfield reports. "We have definitely seen a big improvement in some of the shrubs, pittosporums and emu bushes, the rabbits chew them off. There are some good patches of them coming on."

Badman reports that, on one station, rabbit numbers peaked at 650 rabbits per square kilometres in June 1994. "When we finished the monitoring there in Feb 1997, the rabbit numbers at most sites were at zero. At one site there were 30 to 40. That was the maximum."

Dr Tony Robinson, from National Parks and Wildlife SA, says the success of RCD "is the most exciting thing that has happened biologically for the arid zone in my lifetime".

"If you go up there with a bit of an eye now you can see little acacias on the sandunes which have grown up to nearly one metre high, from earlier rains. There will be another great burst of perennial vegetation coming up from the seed store in the soil. In normal circumstances as the country dries out, rabbits get a kick along in their breeding and they find every little seedling.

"It is the last chance. All these seeds can remain viable in the soil for incredibly long periods of time. There would come a point, and we were probably nearing that point, when the seed stock was going to be wound down and you couldn't have this recovery.

"It is, if not the event since Europeans have been here, it is up there with the top two." The other? "1972-4, when Lake Eyre really filled completely," Robinson says.

In the early light of an autumn day, the Lake glimmers pinkly, under a sky layered with clouds, low pink grading into yellow and then blue. The brilliant orange sun bursts through, and within half an hour the sun and sky are paler, though midday will deepen the sky overhead into an depthless, almost impossible, blue.

The salt crust breaks with every footstep, and the mud underfoot is soft, sucking. The Lake itself is too shallow to row, the mud thigh deep, too difficult to wade through.

Foam has been cast up, thick with the detritus of life that bloomed so briefly: millions of dead grasshoppers, tiny fish picked clean of flesh, pale moths, seeds and stalks already bleaching under the desert sun.

Over the coming year, they will be joined by heaped carcasses of fish, and finally, when the last of the fish lie putrefying, and the birds have flocked spectacularly and fought for the last of the food, by the bodies of the water birds themselves.

Then the salt will encrust and preserve the shoals of the dead, locking up the nutrients contained in their dead bodies until the waters reach them again.

The salt that haunts the Australian landscape, that has risen to salinise its soil and its rivers, here reaches sublime beauty. The salt flats dazzle in the sun and glow eerily at night. Salt entombs insects, abstracting their forms. It forms stiff skirts around small rocks, of irregular and overlapping crystals, as soft and translucent as fish scales. Other rocks wear thick ruffs of opaque white salt. Salt delicately dusts tracks with tiny cubes the size of sugar crystals. It forms delicate honeycombs with tiny fibres, fragile filaments reaching out into the desert air. Yet it is solid enough to make a speedway: in 1962, on the expanse of Lake Eyre, so flat you could see the curvature of the earth, Donald Campbell broke the world land speed record.

Not every animal benefits from the rains. The Lake Eyre Dragon, which only lives on salt lakes surviving on a diet of ants and occasional other insects, is forced onto the shore.

Some find refuge near mound springs, the result of water trickling up from the Great Artesian Basin, forming vivid green rises, with a tail of verdant sedge, in a moonscape environment.

Read scans the ground, then pounces. His prize is a rare Lake Eyre Dragon. Its skin is salt-coloured, speckled with red and black dots. Its big eyes are fringed with rigid white shell-like eyelashes. It looks unearthly, delicate yet durable, perfectly suited to its environment.

Lake Eyre remains our last frontier, a place that will never be softened by civilisation. Though it is still largely unknown, in many ways Lake Eyre epitomises much that we attribute to the Australian character: an indomitable will to compete, to survive; resourcefulness; and the gambling instinct.

As Puckridge points out, "this is the most climatically variable continent on earth and a lot of difficulty in valuing it has come from our frustration with that, and our Euro-centric heritage that things should be more predicable and manageable and reliable".

Learning to understand Lake Eyre, in all its wild unpredictability, its pitiless mortalities, its fierce beauty, and to accept, even glory in that process, will mean a giant step in learning to live with our land.

Lake Eyre Fact box.

Comprises Lake Eyre North and Lake Eyre South, joined by Goyder Channel

Is an endorheic or centrally draining system, the largest in the world.

The Lake Eyre Basin cover about one sixth of the continent, with a 1.2 million square kilometre catchment.

It takes water from the Cooper Creek and the Diamantina/Warburton in the north east, from the Macumba to the north, the Neales to the north west, and Margaret, Stuart and Gregory Creeks to the south.

It held a substantial amount of water in 1950, 1956, 1971, 1974, 1976, 1989 and 1997

The most extensive filling occurred in 1974 when it filled to capacity with 34 cubic kilometres of water, and covered 9,500 square kilometres. The water reached a maximum depth of 5.7 metres.

It is the lowest point in Australia, 17 metres below sea level.

Depth of the salt crust up to 460mm

Weight of the salt crust 400 million tonnes

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