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Philipps-Universität Marburg
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Abstract
Fragmentation and isolation are considered
prominent reasons for the loss of biodiversity in modern
landscapes. Principle conclusions concerning fragmentation,
population linkage, and risk of extinction however are
questionable if they are based on data of active dispersal
only. Distances of passive dispersal of terrestrial
invertebrates by vectors, like rivers, exceed maximum active
mobility as shown by field experiments at the Lahn river (near
Marburg, Hesse) and the Elbe river (near Dessau, Saxony-Anhalt)
in 2000 to 2002 and experiments in the laboratory. Marked
Arianta arbustorum (Gastropoda, Helicidae) were released at the
Lahn river. Individuals travelled a maximum distance of 2.1 km.
At the Elbe river Helix pomatia drifted up to 19.8 km
downstream. In the laboratory A. arbustorum still floats on the
water surface for up to 32 h (+17,5°C water temperature). This
would allow for a transport of more than 173 km at a flow speed
of 1.2 m s-1. Thus, passive dispersal by rivers could be a key
process of recolonisation of dynamic habitats of floodplains
and cultural landscapes. This hypothesis is further supported
by high numbers of terrestrial invertebrates transported alive
by the running water during flood conditions. At the Rhine
river (Kühkopf-Knoblochsaue, near Darmstadt) drifting plant
debris carried 4170 (SE +/-738) individuals of terrestrial
invertebrates per 100 liter debris (flood conditions, March
2001). At the Lahn river 2191 (SE+/-279) and 1011 (SE+/-157)
individuals per 100 liter plant debris were captured by a drift
sampler (January and February 2001). Habitats along rivers are
arranged longitudinally. Thus, the chance for washed-away
individuals to find a suitable habitat is rather high. This
probability is increased as Arianta arbustorum has been shown
to be able to search actively for suitable habitats near
landing locations.
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Dates
Created: 2003Issued: 2004-04-20Updated: 2011-08-10
Faculty
Fachbereich Biologie
Publisher
Philipps-Universität Marburg
Language
ger
Data types
DoctoralThesis
Keywords
passive dispersalVerbund , IsolationPassive AusbreitungdriftwoodTreibholznature conservationFragmentation , PopulationsökologisolationNaturschutzProzessschutz , Totholzwoody debrisraftingGenistfragmentation
DFG-subjects
ÜberschwemmungDriftLaufkäferHochwasserAue , Gehäuseschnecken
DDC-Numbers
570
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Tenzer, Christiane: Ausbreitung terrestrischer Wirbelloser durch Fließgewässer. : Philipps-Universität Marburg 2004-04-20. DOI: https://doi.org/10.17192/z2004.0242.
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This item has been published with the following license: In Copyright