Checking water quality in the Camargue

A famous wetland

The Vallee des Baux, looking north
The Vallee des Baux, looking north
One of the most famous of wetlands is the Camargue of southeastern France, over 140,000 hectares (346,000 acres) of wildlife rich wetlands, pastures, dunes and salt flats that have been formed by the Rhône Delta pushing out into the Mediterranean. Human influence on the Camargue has been important since the twelfth century, when people began to settle in the area. Since then human beings have introduced many changes that have completely and permanently altered much of the natural environment such as agriculture, bull and horse breeding, industrialisation and most recently, tourism. Yet despite this, the Camargue area remains rich in birds and plants and is a place of national and international value.

On the northeastern edge of the Camargue lies the Vallée des Baux. This valley, fifteen kilometres long by three wide, is bordered to the north by the limestone mountains of the "Alpilles" and to the south by the flat pebbly Crau plain which extends out to the delta. The whole area of the Vallée des Baux used to be a huge marshland but was drained and dried from the 17th century onwards for agriculture and to prevent the spread of malaria. However, it still has many lakes and wetland areas and hosts a wide variety of habitats and plant and animal species. Because of its importance for wildlife, the Vallée des Baux is now part of the Natura 2000 EU directive to maintain its biodiversity.

A wetland under threat

All wetlands depend on large quantities of water and any wetland around the Mediterranean, with its long hot dry summers and short rainy season, is vulnerable to water shortages. But wetlands need more than the right water quantity; they need good water quality. Faced with rising amounts of human waste, agricultural chemicals and industrial pollutants, maintaining a supply of clean water to wetlands is not easy. In the Vallée des Baux, falling water quality poses a major problem and species loss is already occurring.

Amelie Fava-Verde of University College London is starting work with A Rocha France to look at water quality in the Vallée des Baux according to agricultural land use. This study, one of the first of its kind in this area, will seek to determine the extent of water pollution, identify the types and sources of pollutants and describe their effects on local wildlife and habitats.

The Vallee des Baux, looking east
The Vallee des Baux, looking east
Testing

Amelie will be based at A Rocha France's field centre of "Les Tourades" in the Vallée des Baux. Her work will involve first of all defining the exact water catchment of the valley, and creating an inventory of agricultural land uses within, to see which ones might pose a water pollution risk, and where. From an initial list of possible pollution types and sources, it will be possible to design a targeted monitoring scheme using a variety of biological and chemical indicators. Biological indicators are organisms such as freshwater invertebrates or fish. Such "bio-indicators" are often more sensitive to pollutants than chemical tests. Invertebrates will be collected by nets and then be brought back to the laboratory for classification and statistical analysis. The fish populations are already known from electric fishing carried out by local fishing organisations. Chemical indicators are substances such as nitrates and phosphates. These will be tested for at various sites as will the amount of dissolved oxygen and suspended particles in the water.

The next step

Once Amelie's work has identified the pollutants and their sources, then the next step will be for A Rocha France to propose ways to counter the problems of decreasing water quality. Management strategies will be proposed through which these pollutants will either be reduced or have their harmful effects limited.

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More details of this work can be obtained from france@arocha.org

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