For the Everglades, or the "river of grass" as the pioneering conservationist Marjory Stoneman Douglas called it in 1947, is dependent for its survival on a copious supply of unpolluted water. The supply was once provided by the Kissimmee river basin but after over a century of interference, that is no longer forthcoming.
Covering 1.5 million acres, the Everglades was designated a National Park 50 years ago. It contains 484,000 acres of shallow sea in the Florida Bay; 572,000 acres of sawgrass sedgemarsh; 230,000 acres of mangrove forest - the largest in the western hemisphere; and 220,000 acres of coastal habitats. Among other things, it's a Unesco Biosphere Reserve, a World Heritage Site, a Wetland of International Significance and an official wilderness.
Outside the National Park is the adjacent and almost as rigorously protected Big Cypress National Reserve which offers up nearly a million acres of subtropical forest and marsh. And a further million or so acres of marsh are also retained as water conservation areas, making up almost 4 million acres of surviving wetland. That might sound massive, but it represents only a quarter of the original Everglades, and that which exists today does so by competing fiercely for what was once a dedicated water supply. Now expanding urban development and agriculture is also after the same water, and faced with this onslaught, it is worth asking if the remainder of the Everglades can survive, let alone flourish.
Species lists for the Everglades would fill a telephone directory. In the park itself there are more than 400 bird species; 60 species of reptiles and amphibians including abundant alligators; over a thousand species of flowering plants from gumbo-limbo trees to air plants such as bromeliads; 125 fish types as well as tens of thousands of insects species ranging from the beautiful black and yellow zebra butterfly to pestilential mosquitoes which attack in vicious battalions. Thirteen Everglades species are classified as endangered. They include the American crocodile; the Florida panther, of which perhaps 30 remain; heavily built wood storks that feed by touch rather than sight; and the West Indian manatee, an incredible plant-eating giant of a sea mammal.
Travelling around the Everglades today, you can't help but be impressed by its wildlife, especially the birds. So it comes as something of a shock to realise that the numbers of wading birds - egrets, herons, storks and others - have declined by a staggering 93 per cent since the 1930s to just 18,000. Endangered wood storks have fallen from around 6,000 to just 500 or so since the 1960s.
The famous naturalist, John James Audubon visited the Everglades a century- and-a-half ago, and could scarcely believe his eyes at the number of birds to be seen. When the Tamiarni Trail - a road crossing the northern Everglades through Big Cypress - was opened in the 1920s, it is said that visitors had to wash their cars at the end of the trip, so dense were the birds overhead.
Whether these stories are actual fact or fondly embellished fiction, there is no doubt that habitat and species losses have certainly occurred on a substantial scale. Levees (embankments) built to contain floodwaters further north and 1,400 miles of canals dug to drain marshes and divert water to the still growing urban population on Florida's east coast, have disrupted the natural flow of water into the Everglades. And over half a million acres of former marsh has long been cultivated to grow a large proportion of the sugar cane, vegetables and citrus fruits produced in the US.
It is not simply a matter of decline in quantity of water reaching the Everglades, but equally in quality. Fertiliser run-off from crops pollutes the supply - a problem which the Everglades shares with wetlands the world over. Maintaining the seasonality of supply is also vital: too much water at the wrong time can, for instance, flood alligator nests and cause fish populations to spread out, reducing the feeding - and breeding - success of many wading birds. Too little water at the wrong time reduces the survival of aquatic invertebrates, fish and birds. But the pressure of urban development and farming has inevitably disturbed the natural patterns.
Wetlands have, until relatively recently, been thought of as wastelands harbouring diseases and pests, but the tide is beginning to turn. After years of being systematically drained and obliterated (in the US, they have vanished at an average rate of 600 hectares a day since colonial times), ecologists are starting to convince governments not only to conserve what few wetlands remain but to restore some of what's been lost. This shift in thinking has its roots in a report written over a decade ago by Paul Adamus for the US Federal Highways Administration.
Adamus brought attention to a whole panoply of wetland functions of human benefit: they can trap sewage and fertiliser run-off; stabilise shorelines to reduce flood damage; provide a breeding ground for commercial fisheries; and offer great opportunities for green tourism. The long-held associations of disease, squalour and death are finally being replaced with a recognition that wetlands are important for health, safety and welfare.
Left to nature, the Everglades was a 50-mile wide river, between a few inches and a few feet deep which moved almost imperceptibly southwards, draining water from Lake Okeechobee and the Kissimmee river basin. In the subtropical heat of winter, all but the deepest water areas dried up, to be flooded again by the hot summer rains. It is this cycle, upon which so much of the ecology of the Everglades depends, which has been so severely disrupted. Historically, over 800 billion gallons of water flowed through the Everglades annually. Today it's only 100 billion. This drying out has allowed vigorous, non-native trees to establish themselves, such as the red-berried Brazilian pepper tree. This was originally planted in gardens, but now they can be found on 100,000 acres of land in the Park. In some places they are so dense, little else can grow.
There is now a programme to eradicate the pepper tree and the Australian paperbark, before they hasten the extinction of some native species. Since 1991, in Big Cypress Preserve, over 6 million paperbarks have been treated with a selective herbicide to kill them off and over 22 million seedlings pulled out. Several hundred acres more have been killed off using airborne herbicide treatment.
The expense of these programmes has stimulated a search for other, cheaper means of eradication. "We're looking at leaf-eating insects as a means of biological control," says Tom Armentano, chief of the Park's Biological Resources Division. "It's a gradual process, and we have to be sure that the insects don't attack any other plant species ... we could be several years away yet."
If much of the Everglades is often left short of water because of supplies, there are huge water conservation marshes in the north-east which often remain flooded all year, encouraging plants and animals that can't tolerate the normal seasonal wetting and drying.
Agricultural water demand in Florida has increased almost five fold since 1960 and there are some simple measures - such as not irrigating crops right in the heat of the day - that are crying out to be implemented. Although domestic and industrial use has fallen since its peak in 1980 (seemingly the result of people - and corporations - heeding the conservation message), with nearly 1,000 people setting up home in the Sunshine State daily, and around 39 million a year on holiday, demand is still bound to increase.
The County authorities have produced development zoning maps, and a new scheme to encourage development away from the Everglades is being promoted, but plenty of waivers to allow new developments are still granted in spite of water shortages. Nonetheless, the arguments to conserve water to help restore a more natural regime in the Everglades, to guarantee year-round domestic supply, to maintain freshwater flows which are sufficient to prevent saltwater inundating aquifers, and to support the valuable freshwater fisheries in Florida Bay and beyond, are gaining acceptance. An interagency task force has been set up under the Water Resources Development Act to develop policies for the whole of the former Everglades ecosystem, from the Kissimmee river basin through Lake Okeechobee and intensive agricultural areas down to Florida Bay and the Keys. It comprises the Park Authority, Florida State agencies including - crucially - the semi-independent South Florida Water Management District and a host of others. It aims to put in place measures to restore water quality and quantity. In the Park, computer models are being refined using historic data in an attempt to determine a natural water regime for this core area of the Everglades. The intention is to restore the natural functioning of the flow both in quantity and seasonality, while recognising that restoring it to its original dimensions - 50 miles wide - is an impossibility because of the substantial land-use changes and development that have taken place over the last few decades.
One of the most tangible results so far is the addition to the Park of over 107,000 acres of land - into which more natural water flows will be restored. It is the largest wetland restoration project ever attempted and years of habitat and species monitoring will be necessary before its success can be gauged.
Reducing the levels of phosphates and nitrates in Everglades water is another goal. Most of these nutrients originate in the intensive agricultural areas to the north where nitrate levels can reach over 2,000 parts per billion (10ppb is considered the natural level) and phosphates over 60ppb (less than 4ppb is natural). Flowing south through the huge water conservation marshes, by the time the water enters the Park the levels drop substantially to a maximum of around 120ppb for nitrate and about 5 to 9ppb for phosphate. Despite this, in some areas more nutrient-loving species (such as bullrush), not naturally abundant here, are replacing native plants and animals adapted to low nutrient levels. This process - called eutrophication - has led to a reduction in the grey-green clumps of algae which float on the water and oxygenate it. Eggs of fish and aquatic invertebrates - the basis of the food chain - survive the dry season by clinging to this moist algal mat.
To combat this, farmland is being acquired by Florida State to construct four water treatment areas totalling 100,000 acres. Here, reedbeds will be developed to filter out these nutrients and clean up the flow into the Everglades. More environmentally sensitive farming practices, such as drilling fertiliser into the soil rather than spreading it on the surface, and research by the US Department of Agriculture to develop sugar cane varieties requiring less fertiliser, should help. In the three years to April 1996, phosphorous run-off from the main agricultural area had already been cut by 45 per cent.
It is not only in Florida that work is being done to save wetlands. Dr Catherine Duigan of the Countryside Council for Wales (CCW), working with other freshwater ecologists, has also been examining the changes in nutrient status of a series of important lakes and other wetlands on Anglesey in north Wales. Enrichment of nutrients from farming and sewage run-off, introductions of non-native species and metal pollution from disused mines are all taking their toll. "We need to focus on the role of changes in land management and sewage disposal in the integrity of lake ecosystems," argues Dr Duigan. She goes on to pose a key question which repeats itself, in a fundamentally similar form across much of the globe: "Can half a million sheep and up to 2 million chickens be managed in a manner to allow their sustainable co-existence alongside a healthy, aquatic environment?" There are many who would answer no.
The Anglesey studies have led to a strategy which is producing practical benefits. With the co-operation of the CCW, the Environment Agency (EA) and voluntary bodies, they are excavating new pools, extending reedbeds, and installing nutrient removal equipment while continuing the work on water quality.
Reducing the input of nutrients, whether from sewage treatment works, animal rearing or fertilisers, is not straightforward. In the UK, the EA regulates discharges from sewage works and intensive animal units but not always in terms of nutrient levels (although recent legislation is in place which is likely to improve this). Reducing diffuse farmland fertiliser and animal manure run-off is more difficult. It has to rely on improved farm management, for instance via Environmentally Sensitive Areas administered by the UK's Agriculture Departments or the CCW's successful Tir Cymen scheme. Reducing fertiliser usage and animal numbers, in exchange for an annual payment to the farmer, can be a component of such schemes.
Florida has no similar schemes for farmers. "Instead," says Larry Belli, deputy superintendent of the Everglades National Park, "our Everglades Forever Act requires the agricultural areas to reduce fertiliser run-off. The government agencies monitor the levels and it's up to the farmers how they achieve the reductions necessary."
It may be small compensation but at least the source of the nitrates and phosphates contaminating parts of the Everglades is identifiable. Unfortunately, the source of mercury pollution isn't. Absorbed by fish when they eat contaminated small plants and animals, the toxic metal concentrates at the tops of food chains. Anywhere where angling is allowed in the Everglades now has a notice advising against eating more than one fish per week. Largemouth bass have mercury levels of up to 1.8 parts per million; levels above 1ppm are considered unsafe for human consumption. Higher quantities have been found in racoons and the endangered Florida panther. Some of this mercury may be leaching out of soils disturbed by crop growing - peaty soils often contain such metals which, if left wet and undisturbed, retain them. Some farmers are now keeping soils wetter by including rice in their rotations and growing other crops needing higher water tables. Some of the mercury may be from airborne pollution or from unknown dumps where old batteries or paints could be sources.
Drawing a boundary around a self-contained habitat of biological interest - a woodland for instance - in order to conserve what lies inside it is not usually problematic, but for wetlands it's completely different. When the Everglades was designated a national park few people gave much thought to what enormous changes were and would continue to be happening outside its boundary across the huge land and water areas draining into it. Putting a stop to the decimation of egret populations for the plumes sought by the millinery trade, or to alligator hunting for their skin, today seems such an easy achievement compared with the complex water quantity and quality issues faced by wetlands the world over.
In Florida, the issue of curtailing further urbanisation and water consumption will have to be tackled. Agriculture is becoming more environmentally sensitive, albeit slowly. Combined with an increasing awareness of the need to preserve - even expand - wilderness areas by politicians and policy makers, and by more of the public, there is hope yet that the Everglades really are for ever. !
The Park's hydrologist Freddie James says:Reuse content