Environmental drivers of heterotrophic euglenoid diversity in Czech bogs

We investigated whether the diversity and community composition of morphologically recognizable heterotrophic euglenoids are associated with major environmental gradients in Czech bog habitats. Bogs and other Sphagnum-dominated wetlands are biodiversity hotspots for microbial eukaryotes, yet the ecological structuring of heterotrophic euglenoids in these systems remains poorly understood. We examined 419 samples from 110 sites from mire sites using live light microscopy, and species occurrences were related to habitat characteristics and water chemistry using correlation analyses, canonical correspondence analysis, detrended correspondence analysis, and variation partitioning. The recorded assemblages were strongly structured by pH, ammonium concentration, water column size, habitat area, and the presence of Sphagnum. Osmotrophic Aphagea dominated small, acidic, ammonium-rich habitats, whereas several phagotrophic and petalomonadid taxa were associated with larger or less acidic sites. The study provides a morphology-based ecological synthesis of a poorly studied group of freshwater protists and shows that heterotrophic euglenoids can contribute substantially to protist diversity patterns along wetland environmental gradients.