 |
||||
Mountain lakes: a precious barometer |
||||
Mountainous and arctic regions are the last bastions of untouched nature in Europe. At least, one might think so. The lakes in these wild and remote regions are, however, affected by our modern pollution. The fragility of their ecosystems makes them both victims and privileged witnesses of environmental and climatic change. For several years, multidisciplinary teams of European researchers have been sounding the changes in these expanses of water. |
||||
|
"High-mountain lakes act like sentinels at the outpost of environmental and climatic changes. They are particularly sensitive to the slightest pollution. Any atmospheric deposition of acidic compounds, heavy metals, chlorohydrocarbons or other volatile organic compounds with a high level of toxicity has an immediate impact on the structure and functioning of their ecosystems", observes Hartmut Barth, scientific officer responsible for the AL:PE and Molar projects for the Research DG. Their sediments are like a history book chronicalling in detail the pollution originating from the industrial revolution or from acid rain, and where one can sometimes find traces of volcanic eruptions. "All these episodes, which are sometimes visible to the naked eye, make it possible for us to go back seven or eight hundred years in a precise and detailed manner", says the Norwegian Bente Wathne, scientific coordinator of the European Molar project (Monitoring of Lakes in Arctic and Alpine Regions). Building on successesBeing the indicators of choice, these ecosystems offer researchers valuable avenues of enquiry to find out more about the biological impact of changes in air quality and in the climate. To pursue this aim, the Molar project has brought together 23 scientific institutions in 13 different countries. "This broad partnership has worked very well. Scientifically, it has enabled us to obtain a general picture of Europe, essential in the context of pollutants, where borders are, of course, irrelevant", comments Vera Straskrabová, a Czech partner. Molar is an extension of two previous European projects, AL:PE1 (Acidification of Remote Mountain Lakes: Palaeolimnology and Ecology) and AL:PE2 (Remote Mountain Lakes as Indicators of Air Pollution and Climate Change). "These two projects made it possible for us to get a preliminary overall picture of these lakes, based on the analysis of sediments and other chemical and biological studies", explains Simon Patrick, the administrative coordinator of the project, from the Environmental Change Research Centre (University College of London). "Encouraged by these successes, Molar has focused on a number of key sites from which minute data can be obtained on the dynamics of these ecosystems over a period of time and the way in which they behave when confronted with various disturbances". The threats now weighing over these sites have been identified. The most worrying trio includes acidifying deposits, toxic atmospheric pollutants and the threat of climate change. Mountain lakes are particularly sensitive to these hazards for various reasons: having very soft water, they do not neutralise the acid substances which they absorb from their catchment area properly; levels of nitrates are high because there is little vegetation around to bind these molecules. Some pollutants, such as mercury and volatile organic compounds, have a tendency to accumulate in cold regions. Finally, because climate changes in Europe will be more pronounced in alpine and arctic zones, this could take the form of a rise in temperature of lake waters because periods of thaw are increasing. On the trail of disturbancesResearchers have been able to confirm that all the lakes studied, even those which are very far from inhabited and industrial areas, have suffered to differing degrees from atmospheric pollution. Acidity, for example, influences fauna, flora and the whole food chain. Organic pollutants such as PCBs or DDTs accumulate in living organisms until, finally, they are concentrated in the tissues and organs of fish, to the extent that in some places fish are no longer fit for consumption. "From whichever angle we study these lakes - whether analysing their fauna, acidity or their heavy metal levels - the overall picture is the same", explains Bente Wathne. "Central and Eastern Europe are very badly hit, in particular because of the presence of toxic pollutants. The damage is gradually less prevalent in the North and the South of the Continent. There is one positive element to be stressed, however. Some types of nitrogenous and sulphurous pollution have been tending to abate in recent years." In seeking to understand the links between disturbances and physical, chemical and biological observations of these ecosystems, European scientists are hoping to develop prediction models for all environmental changes (acidification, pollution or climate change). "Thanks to the successive projects devoted to mountain lakes, we have enough precise data to calibrate the models", explains Rick Batterbee, researcher at the University College of London. "Our ambition is to obtain a broader picture for all mountain lakes in order to test different scenarios". "A particular feature of high-mountain lakes is the speed with which they react; any rise in temperature, for instance, will be reflected in a change in the pH of the water and will rapidly influence all the aquatic ecosystems at a high altitude. These delicate ecosystems act like warning bells, enabling us to take essential management decisions and put policy measures into motion. For this reason, these research projects seem particularly worthwhile to me", concludes Hartmut Barth. The successor to the Molar project, which has been given the name Emerge, is already up and running, moreover… |
  Etang d'Aubé (France) and Lochnagar (Scotland) - "A particular feature of high?mountain lakes is the speed with which they react; any rise in temperature, for instance, will be reflected in a change in the pH of the water and will rapidly influence all the aquatic ecosystems at a high altitude." © J.C. Massabuau © N.Rose |
|||
