Search

Neozoa werden als gebietsfremde Arten definiert, welche nach 1492 direkt oder indirekt durch den Menschen eingeführt wurden und selbstreproduzierende Populationen zu bilden im Stande sind (Essl & Rabitsch 2002). Biologische Invasionen sind schon seit dem Zeitalter des Kolonialismus ein bekanntes Phänomen, gegenwärtig hat das Problem in einer Zeit der Globalisierung von Wirtschaft und Tourismus und einer globalen Klimaveränderung jedoch eine neue Dimension und Geschwindigkeit erreicht. In Österreich gibt es grundsätzlich eine gute Datenbasis über das Auftreten von benthischen Einwanderern. Bereits in der älteren Literatur findet man dazu einige Hinweise, z.B.: Strouhal (1939), Vornatscher (1965) und Liepolt (1965–67). Größere Aufmerksamkeit wurde dem Phänomen invasiver Arten seit der massiven Ausbreitung der Dreikantmuschel Dreissena polymorpha geschenkt, als sich diese in den 1970er Jahren in vielen Flüssen und Seen in einem sehr kurzen Zeitraum ausbreitete. Verstärkte Beachtung wurde den Neozoa in der Limnologie aber erst im letzten Jahrzehnt zuteil, als die Fundnachweise immer häufiger wurden und sowohl ökonomische als auchbemerkenswerte ökologische Auswirkungen durch invasive Arten vermutet oder nachgewiesen wurden. Beispielsweise belegte Gruber (2006), dass der autochthone Steinkrebs (Austropotamobius torrentium) bereits bis in die Quellregion hinein durch den amerikanischen Signalkrebs (Pacifastacus leniusculus) verdrängt wird. In Österreich entstand als Folge des erhöhten Problembewusstseins in den letzten Jahren eine Reihe von umfassenden Publikationen zum Thema Neobiota: „Invaders“ (Aescht & al. 1995), „Neobiota in Österreich“ (Essl & Rabitsch 2002) und „Aliens“ (Wallner 2005). Während die überwiegende Zahl der Publikationen zum Thema Neozoa von taxonomischen Fachspezialisten stammt und deshalb zumeist auf eine oder einige ausgewählte Tiergruppen beschränkt bleibt, basiert vorliegender Beitrag auf Monitoringdaten und gewässerökologischen Untersuchungen, in w, Based on 9,544 data sets from 1,060 Austrian rivers and streams the paper gives a quantitative and qualitative overview of the occurrence and distribution of benthic invertebrate neozoa in Austrian running waters. Excluding those species that have been recorded only as single findings or which inhabit greenhouses with no connection to natural water bodies, a total number of 46 benthic invertebrate species can be classified as neozoa for Austria. Referred to the known number of about 3,200 benthic macro-invertebrate species the neozoa fauna comprises only a small amount of 1.8 %. On the other hand these neozoa colonise 16.1% of the investigated water bodies. Most investigation sites are inhabited by only one neozoa species. The maximum number of neozoa species found at one investigation site was not higher than 13. However, at some river sites the abundance of neobiota specimens can clearly dominate the benthic community. E. g. a maximum number of about 500,000 Corophium curvispinum individuals per m² (99% of the total abundance) with a biomass up to 0.6 kg fresh weight per m² has been observed in the River Morava (Lower Austria), a neozoa biomass of 7 kg/m2 (Corbicula fluminea) was documented in a muddy Danube harbour at Linz, Upper Austria. In contrast to the indigenous fauna, which is mainly composed of insects (85%) the neozoa fauna is dominated by Crustacea (53%) and Mollusca (24%). 47% of the neozoa species originate from European regions, mainly the ponto-caspian area. Other important donor areas are North America and South East Asia. With respect to aquatic neozoa in Austria, the River Danube can be clearly identified as the main immigration channel of the ponto-caspian (most of the Mollusca and Crustacea neobiota species) as well as the mediterranean fauna (Atyaephyra desmaresti) and other species that spread via Western Europe, respectively. Although most of the benthic invertebrate neozoa have never left the main Danube channel, a steady immigration from D

STAR is a European Commission Framework V project (EVK1-CT-2001-00089). The project aim is to provide practical advice and solutions with regard to many of the issues associated with the Water Framework Directive. This paper provides a context for the STAR research programme through a review of the requirements of the directive and the Common Implementation Strategy responsible for guiding its implementation. The scientific and strategic objectives of STAR are set out in the form of a series of research questions and the reader is referred to the papers in this volume that address those objectives, which include: (a) Which methods or biological quality elements are best able to indicate certain stressors? (b) Which method can be used on which scale? (c) Which method is suited for early and late warnings? (d) How are different assessment methods affected by errors and uncertainty? (e) How can data from different assessment methods be intercalibrated? (f) How can the cost-effectiveness of field and laboratory protocols be optimised? (g) How can boundaries of the five classes of Ecological Status be best set? (h) What contribution can STAR make to the development of European standards? The methodological approaches adopted to meet these objectives are described. These include the selection of the 22 stream-types and 263 sites sampled in 11 countries, the sampling protocols used to sample and survey phytobenthos, macrophytes, macroinvertebrates, fish and hydromorphology, the quality control and uncertainty analyses that were applied, including training, replicate sampling and audit of performance, the development of bespoke software and the project outputs. This paper provides the detailed background information to be referred to in conjunction with most of the other papers in this volume. These papers are divided into seven sections: (1) typology, (2) organism groups, (3) macrophytes and diatoms, (4) hydromorphology, (5) tools for assessing European streams with macroi