Hidrológiai Közlöny 1998 (78. évfolyam)

4. szám - Fülöp István Antal–Józsa János: A neruális hálózatok világa

262 Bothár, A. & B. Ráth, 1994. Abundance Dynamics of Crustaceans in different biotopcs of the „Szigetköz" side aim system, River Danube, Hungary. Verh. Internál. Verein. Limnol. 25:1684-1687 Bolhár, A., & B.Ráth, 1997. Diversity, connectivity and variability of littoral, surface water ecotones in three side arms of the Szigetköz Region (Danube/Hungary). In: J.Gibert et al. (ed ), GroundwaterSurface Water Ecotones Univ. Press, Cambridge, 57-67. Forró, L„ & P. Gulyás, 1992. Eurytemora velox (Lilljeborg, 1853) (Copepoda, Calanoida) in the Szigetköz region of the Danube. Mise. Zool. Hung 7: 53-5S.Gulyás, P., 1996. Veranderungen des Rotatoría- und Crustacea-Planktons in den Nebenarmen des Deichvorlandes der klemen Schüttinsel (Szigetköz) infolge der 1. ábra Cruslaceák fajszáma, valamint az egyedszámok, diverzitás és egyenletesség éves átlagértékei vízi makrofitonokka! borított élőhelyeken, Schisler holtág Umleitung der Donau in der Slowakei. 31. Konferenz der IAD, Baja-Ungam, Wissenschaftliche Referate, 213-218. Kiss.K.T, 1997 A 90-es évek szigetközi fitoplankton kutatásának néhány fontosabb eredménye. Hidrológiai Közlöny, in print Ráth, B„ 1997. Verbreitung von aquatischen Makrophytenbestanden im Flupbett des frílheren I lauptarmes der Donau (Szigetköz, Stromkm 1826-1843). 32. Konferenz der IAD, Wien - Austria, Wissenschaftliche Referate, in Print. Köszönetnyilvánítás A kutatás az OTKA (T016835) és a Környezetvédelmi és Területfejlesztési Minisztérium támogatásával készült. 2. ábra Cruslaceák fajszáma, valamint az egyedszámok, diverzitás és egyenletesség éves átlagértékei vízi makrofitonokkal borított élőhelyeken, Lipóti morotva 1991 1992 1993 1994 1995 1996 • egyedszám (ind/l) nTajszám H II III I 1991 1992 1993 1994 1995 1996 • H: diverzitás — J:egyenletesség 0.9 0.8 0.7 0.6 0.5 0.4 1993 1994 1995 • egyedszám (ind/l) — rrfajszám 1996 H J • III 0.9 0.8 0.7 0.6 1993 1994 1995 1996 • H:diverzitás -~-J:egyenletesség Results of Zooplankton (Cladocera, Copepoda) investigations in the Szigetköz/Hungary, 1991-1996 Bothár,A. Abstract Regular investigations of crustaceans (Cladocera, Copepoda) in the Szigetköz-region have been carried out between 199119%. In 1992, after the diversion of the Danube (C-variant), the 32 km stretch of the originál main arm (1843-1811 river km) became a part of the abandoned river bed The side-arm system of the floodplain and the abandoned Danube stretch became disconnected. For the artificial water supply, water recharge system on the floodprotccted area, and on the floodplain was constructed in 1993-96. In 1995, a bottom sill was constructed in the abandoned Danube channel; the damned water level on its upstream has provided a permanent water replenishment by gravitation ínto the floodplain branchsystem. As a consequence of water engineenng activities, alluvial stages of several water bodies, together with the composition of their flóra and fauna, have basically changed. In the abandoned Danube, in consequence of the contracted stream bed, lower water depth, slower current velocity, and intensive silting, new biotopes have developed, covered by macrophyton stands As a consequence of the ongoing artificial water supply since 1993, water levels became permanently higher in the different water bodies both in the floodplain and in the floodprotected area The greatest damage caused by the higher water levels, and by the cut-offs that several water bodies of unique character have disappeared (e.g. Disznós, Forrásos), or basically altered (e.g. Csákányi-Danube, Ásványi-Danube), including the disappearance or uniformisation of their Crustacean fauna. Crustaceans, adapting to the newly created conditions, even in 1996 were able to maintain diverse communities, differing from each other in valuable dormnant species, m the still existing morphologically and botanically altered water bodies (e.g. Schisler dead-arm, Zátonyi-Danube, Lipóti march) and in the newly created biotopes (e.g. littoral region of the abandoned-Danube). Open water areas lost their importance as habitats for crustaceans. For the maintaining of the still existing and newly developed mosaicity and diversity of habitats, it would be desirable the controlling of water levels, and water level fluctuations which could increase not only the diversity and eveness of crustacean communities but even the seasonal variability, reduced by the continuous water supply