Influence of tributaries on the periphytic diatom community in a floodplain

Andressa Bichoff, Nicolli Cristina Osório, Daiane Trevisan Ruwer, Kisay Lorena Adame Montoya, Bárbara Dunck, Liliana Rodrigues


In impacted floodplains, small tributaries have an essential role in the maintenance of ecosystem biodiversity. Aim: We aimed to characterise the periphytic diatom community (Bacillariophyceae) in a protected area at the Upper Paraná River floodplain. Considering the importance of those tributaries as a source of resources and propagules, we expect that species present in the main river channel (mainly in the last stretch) would be a subset of the community present in the tributaries. Methods: The study area is located in the last non-dammed stretch of the Paraná River in this floodplain, with the contribution of several tributaries. Sampling was performed in 2014 in two tributaries and three sites at the Paraná River main channel, and the periphytic material was obtained from petioles of the aquatic macrophyte Eichhornia azurea (Sw.) Kunth. Results: We identified 115 diatom taxa. Higher values of species richness were registered in the tributaries (T1 and T2), and higher densities at sampling sites under the direct influence of the tributaries (P1 and P3). Results show a higher similarity between tributary communities and a higher dissimilarity of P2 (Paraná River) with the others, since it is not directly influenced by the tributaries. Moreover, contrary to expected, beta diversity results evidenced a high species turnover among sampling sites, and that species present at the last stretch of the river are not subsets of upstream communities, likely provided by dispersal from many habitats, and not only from specific sites. Conclusion: In this way, results indicate the great importance of conserving several tributaries, since they act in concert as a source of propagules for the establishment of communities along this floodplain stretch.



Benthic algae; beta diversity; turnover; conservation

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