Bach dragonflies before the Aus?

Near-natural, clean watercourses in the Weser-Ems region in short supply

Belongs to the endangered species of dragonfly: The Little Blue Spear (Orthetrum coerulescens). © Tammo Lieckweg, University of Oldenburg
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Dragonflies, which rely on clean, natural streams and rivers, are still struggling to survive - at least in the Weser-Ems region. Scientists at the University of Oldenburg have now come to this conclusion in a new study. They examined the presence of running water dragonflies in 2006 and compared them with older stock records (since 1980).

Many species of dragonflies depend on specific water types as their habitat. In Lower Saxony, there are no more natural streams or rivers that are untouched by man, and even natural riverine sections are rarely found in some regions - despite all the efforts made by nature conservation. In particular pollutant inputs, over-fertilization and destruction of the natural irrigation structure threaten the sensitive river water dragonflies.

Overall, the researchers gathered around Professor Rainer Buchwald and the landscape ecologist Tammo Lieckweg from the Institute of Biology and Environmental Sciences new data on seven dragonfly species. According to the results of the scientists, the stock situation in recent years has remained largely unchanged - "and that means: remains endangered", says Buchwald.

Habitats massively threatened

The most common is the blue-winged demoiselle found on 14 different streams. About half of the populations found are in the Osnabrück area; others are located above all in the vicinity of Wildeshausen and Lingen in the Emsland. All species still have very few, often strongly isolated deposits. Their habitats are also affected according to the results of the researchers by nutrient inputs and intensive entertainment activities in the waters.

Close-to-nature, clean watercourses are valuable but also sensitive habitats, which must be preserved under all circumstances, summing up the scientists from Oldenburg. They plead for further renaturation measures as well as the careful care and maintenance of running waters with the aim to permanently secure particularly rare and endangered animals and plants in their existence. display

(idw - University of Oldenburg, 22.03.2007 - DLO)