Uta Langheinrich

Self-purification in Upland and Lowland Streams

Ecological investigations at four streams in Saxony-Anhalt have shown that there are considerable differences between the self-purification power of upland and lowland streams. This result is reflected in chemistry and in microbiology. The structure of the bottom substrate mainly influences the degree of self-purification in connection with rate of flow and flow velocity. The results and differences are demonstrated using the example of Katzsohlbach in the landscape unit “Mittel- and Unterharz” and the stream Olbe in the landscape unit “Magdeburger Borde”. Selbstreinigung von Mittelgebirgs- und Flachlandbachen Okologische Untersuchungen an vier Fliesgewassern in Sachsen-Anhalt haben gezeigt, dass betrachtliche Unterschiede zwischen der Selbstreinigungsleistung von Mittelgebirgs- und Flachlandbachen existieren. Dieses Ergebnis spiegelt sich im Chemismus und der Mikrobiologie wider. Die Sohlenstruktur beeinflusst im Zusammenhang mit dem Durchfluss und der Fliesgeschwindigkeit hauptsachlich den Grad der Selbstreinigung. Die Ergebnisse und Unterschiede werden am Beispiel des Katzsohlbaches in der Landschaftseinheit „Mittel- und Unterharz“ und der Olbe in der Landschaftseinheit „Magdeburger Borde“ dargestellt.

Ditches and canals in management of fens: opportunity or risk? A case study in the Dromling Natural Park, Germany

Up until the present, canals and ditches in Europe have been used to drain and thus devastate fens (lowland moors). However, in many cases, their function can be changed from drainage to irrigation and re-wetting of previously drained areas. These systems of canals and ditches are characteristic elements of the historically developed cultural landscape. Therefore, management and development plans should be oriented towards their continual maintenance. Despite the density of canals and ditches in many regions of Germany, especially of Eastern Germany, there are only a few studies to evaluate these systems of waterways, and an integrated approach towards their assessment has been totally absent. Existing approaches for typology and assessment of flowing waterbodies have been investigated in the Drömling Natural Park with regard to their applicability to such artificial canals and ditches. Special attention is given to the composition of macroinvertebrate fauna and the assessment of factors that determine it. Surprisingly, most water sectors have a high conservation value. High total numbers of species correlated well with the occurrence of endangered species. p ]Among the macroinvertebrates, limnophil and phytophil species were dominant, but rheophil fauna were also commonly present. This was caused by the intermediate status of canals and ditches, since they are neither completely flowing nor completely stagnant waterbodies. Habitat quality of these waters is determined by a small number of morphological parameters: bank steepness, depth of bottom, substrate diversity, hydraulic structures, and the structure of surroundings. In the framework of management and development measures, they should be maintained and improved for the future. To assess water quality, the Saprobic index and the Chemical index were appropriate, but for indication of trophic status, the Macrophyte-trophic index was adequate. Estimation of ecological integrity by a multimetric index using macroinvertebrates indicates that waterbodies are in a good status according to the demands of the European Water Framework Directive.

Streams in the Harz National Parks (Germany) — a hydrochemical and hydrobiological evaluation

Abstract Between 1995 and 2001, 16 measuring points at small and medium sized brooks in the Harz National Parks were sampled. The samples have been evaluated by means of hydrochemistry and macroinvertebrate biology. Although nearly all streams are largely uncontaminated by oxygen-consuming substances, they are settled only by a small number of macroinvertebrate species. There is a clear correlation between this number and pH. The reduction in species number with decrease of pH is mainly caused by the absence of most Ephemeroptera, some Coleoptera and Trichoptera. Comparing biological evaluation of acidity with physico-chemical measurements, a unacceptable underestimation was found. The reason could be that different sensitivities to acidification between regional populations seem to exist. Despite of the low species number, there is a very specific macroinvertebrate fauna that emphasizes the conservation value of the Harz National Parks.

Eignung von Fischaufstiegsanlagen an Obermain und Rodach als Lebensräume und Migrationshilfen für Fische und Makroinvertebraten

Am Obermain und an der Rodach in Oberfranken haben in den letzten 20 Jahren umfassende und aus ökologischer Sicht erfolgreiche Renaturierungsmaßnahmen stattgefunden. Da das Fließgewässerkontinuum zwischen den Renaturierungsstrecken jedoch weiter durch mehrere Querbauwerke beeinträchtigt war, wurden Fischaufstiegsanlagen in Form von zwei Umgehungsgerinnen und einem Tümpel-Becken-Pass errichtet. Die vorliegende Arbeit untersucht die Funktionsfähigkeit dieser Anlagen hinsichtlich des Fischaufstieges aber auch hinsichtlich ihrer Eignung als Lebensraum und Wanderkorridor für Makroinvertebraten. Die naturnah gestalteten Umgehungsgerinne werden sowohl von allen vorkommenden Fischarten als auch von den aquatischen Makroinvertebraten angenommen. Hinsichtlich der Besiedelung mit Wirbellosen sind sie mit naturnahen Fließgewässerstrecken vergleichbar, was schon deshalb bemerkenswert ist, weil die direkt oberund unterhalb der Anlagen liegenden Flussabschnitte wenig naturnah sind. Der untersuchte Tümpel-Becken-Pass schneidet weniger gut ab. Er wird nicht von allen Fischarten in gleicher Weise angenommen und hinsichtlich seiner Makroinvertebraten-Fauna nur als unbefriedigend bewertet.