Topic modeling reveals thermally partitioned microbial communities across Great Lakes size fractions
Researchers applied topic modeling to eight years of microbial data from the Laurentian Great Lakes, identifying distinct microbial subcommunities organized by temperature and lake chemistry across four size-fractionated biological groups. Temperature was the dominant environmental factor structuring these communities, with secondary drivers varying by size fraction and dispersal capacity. The findings demonstrate that thermal stratification creates largely non-overlapping microbial assemblages, with specialized cold-water lineages absent in warm waters.
Using Latent Dirichlet Allocation (LDA) topic modeling on a 16S rRNA amplicon time series, researchers analyzed microbial communities across four size-fractionated biological blocks in the Great Lakes: free-living prokaryotes, particle-associated prokaryotes, and small and large chloroplast-containing eukaryotes. The analysis revealed ecologically coherent subcommunities with consistent taxonomic identity at the order and class level. Temperature emerged as the dominant environmental driver across all blocks, with thermal stratification and lake chemistry organizing microbial communities coherently. Differences in Shannon entropy between blocks reflected fundamental differences in dispersal capacity, with free-living prokaryotes and large eukaryotes showing higher mixing than particle-associated prokaryotes and small eukaryotes. Cold-water specialists, including chemolithotrophic deep-branching lineages and silica-dependent diatoms, occupied ecological niches with no warm-water equivalents.
What's missing
The study's limitations regarding temporal coverage (eight years may not capture longer-term climate trends), potential biases in 16S rRNA amplicon sequencing, and whether findings are generalizable to other freshwater lake systems are not discussed in the abstract provided.
What different sources said
- bioRxivCenter
Topic modeling reveals thermally partitioned and taxonomically distinct microbial subcommunities across prokaryotes and phytoplankton in the Laurentian Great Lakes
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