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Updated: Aug 19, 2026

Modeling the Size Spectrum for Macroinvertebrates and Fishes in Stream Ecosystems
Published on: July 30, 2019
Impact of a major flood event on riverine fish community composition
Lidia Marszał1, Carl Smith2, Bartosz Janic3
1Department of Ecology & Vertebrate Zoology, University of Lodz, Banacha 12/16, Łódź, 90-237, Poland; Museum of Natural History, Faculty of Biological Sciences, University of Wrocław, Sienkiewicza 21, Wrocław, 50-335, Poland.
Abstract:
Extreme floods are increasingly frequent disturbances in riverine ecosystems, yet their impacts on fish community structure remain variable. We assessed the effects of a major 2024 flood on riverine fish assemblages in Polish submontane and lowland streams using pre- and post-flood electrofishing data from 36 paired sites. Presence/absence-based PERMANOVA revealed no significant flood effect on overall community composition, with habitat gradients (elevation, stream order, geology, riparian land use) explaining approximately 35% of variation. NMDS ordination and dispersion tests confirmed stable compositional patterns and variability. Indicator species analysis identified only common rudd (Scardinius erythrophthalmus) as significantly associated with post-flood conditions. A Bernoulli GLMM showed a significant flood × guild interaction, with limnophilic species decreasing and rheophilic species increasing in probability of occurrence post-flood. Guild-specific richness changes supported these shifts. Results indicate resilience in taxonomic composition but subtle functional reorganisation towards lotic-tolerant taxa, highlighting the overriding role of habitat heterogeneity in structuring riverine fish communities following major disturbance.
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