Spatial-scales and local factors influencing nanoflagellates assemblage from a floodplain fluvial system

FERNANDO UNREIN; GISELA MAYORA; VANESA DI PASQUALE; SEBASTIÁN METZ; MELINA DEVERCELLI; PAULA HUBER; BERENICE SCHNEIDER

Natal

Workshop; 18th WORKSHOP OF THE INTERNATIONAL ASSOCIATION OF PHYTOPLANKTON TAXONOMY AND ECOLOGY (IAP); 2017

INTERNATIONAL ASSOCIATION OF PHYTOPLANKTON TAXONOMY AND ECOLOGY

Nanoflagellates are functionally important components of the plankton and in microbial foodwebs since they link the different path of energy flow due to their heterotrophic, autotrophic,and mixotrophic nutrition. The variability in nanoflagellates assemblage among habitats isregulated by a combination of abiotic factors, biotic interactions, and dispersal processes. Infloodplain fluvial systems, the dispersal potential is mainly related to the hydrologicalconnectivity of habitats and hence, to the spatial configuration. In this sense, the shaping oflocal communities depends not only on the local environmental factors, but also on the spatialprocesses operating at multiple scales as it is stated in the metacommunity frame. Theobjective of this work was to analyze the different factors and scales intervening in thenanoflagellates? assembly of the Middle Paraná floodplain. With this purpose, we compare i)two geomorphological units characterized by different drainage pattern and connectivitystrength (meandering and anastomosed), ii) type of environments with different hydrologicalinfluence, and iii) patches within each environment (pelagic and vegetated). A total of twentyeightlotic and lentic environments were sampled during a low water period. When it waspossible, pelagic, and vegetated sampling points were established. The morphologicalidentification and counting of nanoflagellates assemblage was performed using anepifluorescence microscope. Measurements of spatial, physical, and chemical variables, andmacrophyte coverage and composition were made. Additionally, heterotrophic, andphototrophic picoplankton were counted by flow cytometry since they are considered themain food source of heterotrophic flagellates. We decomposed the variation explained byspatial (dbMEM eigenfunction) and local factors by a variance partition analysis. Weperformed NPMANOVA and SIMPER to compare nanoflagellates structure amonggeomorphological units, environments, and patches, and the assemblage divergence wasanalysed with PERMDISP.