L. Forró szerk.: Miscellanea Zoologica Hungarica 10. 1995 (Budapest, 1995)

Tittizer, T., Leuchs, H.; Banning, M.: The consequences of river impoundments for the macrozoobenthos - demonstrated at the example of the River Danube in Germany

Nearly all experts involved agreed that the stocking with fish could only be a unique action of short-term effect. That is why in late May 1992 on four embankment reaches rip-rap rock was dumped in different dimensions. This was a pilot project with the aim to promote the development of a more or less intact fish fauna and to provide shelters for the fish fry. Studies on the effectivity of the action are still going on. Nevertheless, the productivity of the impoundment has still remained high. A look at the dominance structure on the river bottom (Fig. 12) reveals that a change in populations had taken place here. In November 1987 chironomids had been highly eudominant (67 %), then in the Septembers of 1988 and 1989 the most individual-rich elements of the benthic biocoenosis were nearly evenly distributed between the three main taxa, i.e. chironomids, the sphere shell Sphaerium corneum and the crustacean Corophium curvispinum. The communities that were observed in the late summers of the two following years, were marked by the high eudominance of the sphere shell Sphaerium corneum, with 63 % and 56 %, respectively. In late August 1992 finally, Corophium curvispinum was predominant. In the inventories made in the late summer of 1993 for the first time none of the species was eudominant. The highest dominance, with now 19 %, was again that of the crustacean Corophium curvispinum, whereas the share of chironomids even dropped to the class of recedents. Although in September 1994 Corophium curvispinum was dominant again it seems that eight years after the beginnning of the damming-up the life community on the bottom of River Danube slowly begins to stabilize with the maximum of settlement being shared by several subdominant species. References Anderwald, RH. (1991): Quantitative Analyse der Entwicklung und Mobilität ausgewählter Trichopterenpopulationen der Donau und deren Abfiängigkeit von Umweltvariablen. — Dissertation an der Formal- und Naturwissenschaftlichen Fakultät der Universität Wien (Wien), 127 pp. Bayerisches Staatsministerium für Landesentwicklung und Umweltfragen Bslu (Hrsg.) (1985): Wasserwirtschaftliche Rahmenuntersuchung Donau und Main. - Bayer. Staatsmin. f. Landesentwicklung u. Umweltfragen (München) 204 pp. Einsele, W. (1960): Die Strömungsgeschwindigkeit als beherrschender Faktor bei der limnologischen Gestaltung der Gewässer. - Wissenschaftliche Supplemente zu Österreicfts Fischerei 1(2): 1-40. Kothé, P. (1968): Hypania invalida (Polychaeta, Sedentaria) und Jaera sarsi (Isopoda) erstmals in der deutschen Donau. - Arch. Hydrobiol./Suppl. 34 (Donauforschung 3): 88-114. Leuchs, H., Tittizer, T. & Banning, M. (1991): Räumliche und zeitliche Verteilung von endemischen Arten in der Donau. - Erweiterte Zusammenfassungen der Jahrestagung der Deutschen Gesellschaft für Limnologie (DGL) vom 30.9.-6.10.1991 in Mondsee: 300-304. Nielsen, ET. (1962): A note on the control of the chironomid Gyptotendipes paripes Edwards. Mosquito News 22: 114-115. Patterson, R. S., Windeguth von, D.L., Glancy, B. M. & Wilson, F. L. (1966): Control of the midge Glyptotendipes paripes with low-volume aerial sprays of malathion. - J. econ. entom. 59: 864-866. Ryser, H. M., Scholl, A. & Wülker, W. (1983): Revision der Gattung Chironomus Meigen (Diptera) VII: C. muratensis n. sp. und C. nudiventris n. sp., Geschwisterarten aus der plumosus-Gmppe. - Revue suisse Zool. 90: 299-316.