Metabarcoding Reveals Lacustrine Picocyanobacteria Respond to Environmental Change Through Adaptive Community...

Area of Science:

• Aquatic Ecology
• Microbial Ecology
• Limnology

Background:

• Picocyanobacteria (Pcy) are vital but understudied in freshwater food webs.
• Previous studies on Pcy drivers used total cell counts, yielding inconsistent results.
• High diversity of freshwater Pcy genotypes exists, but environmental associations are unclear.

Purpose of the Study:

• To investigate how picocyanobacterial communities respond to environmental changes in lakes.
• To identify abiotic drivers influencing Pcy abundance, diversity, and community dynamics.
• To compare the utility of microscopy and metabarcoding for Pcy research.

Main Methods:

• Epifluorescence microscopy and 16S rRNA gene metabarcoding were employed.
• Temporal community data were collected over one year in five contrasting lakes.
• Picocyanobacterial abundance, diversity, and community structure were analyzed against environmental variables.

Main Results:

• Total Pcy cell abundance did not consistently correlate with environmental variables across lakes.
• Metabarcoding revealed distinct Pcy communities between lakes, driven by trophic state variables.
• Within lakes, Pcy communities were dynamic, with specific ASVs linked to environmental drivers.

Conclusions:

• Combining microscopy and metabarcoding provides detailed Pcy community characterization and driver identification.
• Lacustrine Pcy communities adapt collectively to environmental changes, maintaining high abundances.
• Future research should consider Pcy strain-specific variability rather than treating them as a single functional group.