CS34 River Dynamics
Date: Wednesday, June 12, 2002
Time: 4:00:00 PM
Location: View Royal
 
FeslC, Inst. of Ecology and Nature Conservation of the University of Vienna, Vienna, Austria, christian.fesl@univie.ac.at
 
BIODIVERSITY AND SPECIES-ABUNDANCE PATTERNS OF THE MACROZOOBENTHOS IN A LARGE RIVER: STOCHASTICITY AS A STRUCTURING FACTOR
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Species-abundance patterns of the dominant benthic taxa, i.e. Chironomidae, Oligochaeta, Bivalvia, Gastropoda, Crustacea, Ephemeroptera and Trichoptera were compared with seven niche-oriented models obtained by computer simulations. Two different approaches concerning the correspondence between species identity and rank were used. Most of the species-rich assemblages could, however, not be described by any model used. Only the Random Fraction model fitted some of them indicating that the species divide the total niche space in a random fashion. The Random Assortment model fitted most of the observed assemblages with low species numbers and the patterns of assemblages which were strongly dominated by one or a few species were not significantly different from a derivation of this model. The results suggest that the relative abundances of these species are completely independent and are governed by stochastically changing environmental factors.