Modellierung des organismischen Response in Buhnenfeldern der mittleren Elbe-Determinierende Umweltfaktoren des Makrozoobenthos der Elbe
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Philipps-Universität Marburg
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Abstract
In order to develop a mathematical model which
reflects the abundance of benthic species in groyne fields of
the river Elbe in relation to the mayor abiotic variables of
its living space, the following steps have been taken: - The
benthos was sampled and the corresponding abiotic parameters
were measured. - Correlation analysis of benthic species and
abiotic parameters was carried out. - The main and determining
abiotic parameters were identified and a mathematical approach
based on RDA (redundancy analysis) was made describing the
abundance of some benthic species in dependence to abiotic
parameters. - The plausibility of the resulting model was
determined by comparison with the relevant literature. - Mayor
environmental deficiencies of the existing groyne fields were
identified and distinctive features were determined to optimize
ecologically sound groyne fields. - Upon these findings new
groyne types were introduced into the model, the hydrological
and morphological abiotic conditions were simulated, and the
resulting distribution of some species was modelled and
graphically displayed in GIS. The surveyed parts of the river
Elbe are characterized by their poor composition of benthic
species. The soft-substrates are mainly colonized by
Chironomidae and Oligochaeta up to 600.000 individuals per
square meter. The quantity of other taxa and individuals is
quite low. The hard-substrate is sparsely colonized, the
dominating taxa are Chironomidae. The multivariate analysis of
the fauna and the abiotic factors by means of the RDA
determines the dependencies of the benthic fauna on the main
variables time, discharge velocity and substrate (in descending
importance). The response characteristics of some species
(especially Limnodrilus hoffmeisteri, Propappus volki and
Robackia demeijerei) proved to be pronounced and could be
assigned to these factors. These findings have been determined
on a high level of significance and were confirmed by the
literature. The polynomial set up on the basis of RDA,
representing the relationship between taxa abundance and
abiotic parameters, as well as the abiotic data calculated by
application of a mathematical hydraulic model of the project
partner were integrated into the project database. The database
served as interface and control unit for the modelling of
scenarios of the taxa behaviour. The simulation results were
visualized in Arcview GIS. The method developed is a tool easy
to handle and to prognosticate changes in the fauna as a
consequence to changes in the hydro- and morphological
conditions of the River Elbe. A list of demands was compiled to
optimize the ecological function of groyne fields, which should
take tasks formerly assigned to the main stream. Modified
groyne types were designed in order to change the conditions in
the groyne fields in the required way, and were integrated in
the model. The resulting morpho- and hydrodynamic conditions
were computed by means of the hydraulic model of the project
partner, and the effects were visualized exemplary with two
species in three groyne field associations. The simulation of
the groyne modifications demonstrated a higher habitat
diversity which resulted in an improved patchiness by the
tested species. It turned out that each river section has to be
investigated individually in order to consider the local
conditions in every part of the groyne fields. The presented
modelling enables decision-makers to investigate various
solutions of bank conserving measures incorporating the
requirements of the ecology and the economy with different
scales. Generally a reconstruction of the semiterrestric river
zones, especially of its groyne fields would be particularly
desirable, but also the ecologically sound rehabilitation of
the river itself and its meadows should be aimed at. A
sustainable design should rather be subordinated to short term
economic profit and, besides the aesthetic and ecological
gains, would include economic advantages as rivers with
comparatively natural shape hardly will need maintenance by
hydraulic engineering (Bohle & Engel-Methfessel 1993). The
authors even wrote in 1993 that it would be desirable "to
consider more extensively the function of rivers in a natural
environment, particularly since the defects arising from an
exclusively technically oriented river management, will turn
out to permanent and also economic constraints?. That is
even more of relevance to the present situation under the
impression of the flood disaster at Elbe and Oder with its
negative impacts on economy and people.
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Supervisor:
Dates
Created: 2003Issued: 2004-03-04Updated: 2011-08-10
Faculty
Fachbereich Biologie
Publisher
Philipps-Universität Marburg
Language
ger
Data types
DoctoralThesis
Keywords
river ElbePotamalGIS , Robackia demeijereiPotamal , currentRDAsubstrateRDAElbe
DFG-subjects
StrömungModell , BuhneMakrozoobenthos
DDC-Numbers
570
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Dirksen, Michael Thomas (128828013): Modellierung des organismischen Response in Buhnenfeldern der mittleren Elbe-Determinierende Umweltfaktoren des Makrozoobenthos der Elbe. : Philipps-Universität Marburg 2004-03-04. DOI: https://doi.org/10.17192/z2004.0081.
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This item has been published with the following license: In Copyright