Planktonic protistan communities in lakes along a large-scale environmental gradient

Area of Science:

• Aquatic microbiology
• Eukaryotic diversity
• Limnology

Background:

• Eukaryotic microbial diversity in inland waters is poorly understood.
• Comprehensive analysis of eukaryotic diversity in low-productivity lakes is needed.

Purpose of the Study:

• To comprehensively analyze eukaryotic microbial diversity in 74 low-productivity lakes across southern Scandinavia.
• To investigate the relationship between diversity, community composition, and spatial/environmental variables.

Main Methods:

• 18S rDNA amplicon sequencing was used.
• Analyzed 74 low-productivity lakes along a longitudinal transect.
• Classified eukaryotic diversity into 1882 operational taxonomic units (OTUs).

Main Results:

• Detected wide diversity of pelagic microbial eukaryotes, with high OTU richness in phytoplankton groups.
• 53.6% of OTUs were autotrophic; 19.4% of heterotrophic OTUs were parasitic.
• Community dissimilarity increased with geographical distance; diversity gradients were explained by spatial structure and regional species pools.

Conclusions:

• Spatial structure, rather than local environment, significantly influences protistan diversity and community composition in these lakes.
• Longitudinal gradients in diversity are likely driven by regional species pools and landscape productivity differences.