Revealing the Differences in Ulnaria acus and Fragilaria radians Distribution in Lake Baikal via Analysis of Existing Metabarcoding Data

Two diatom species, Ulnaria acus and Fragilaria radians, are morphologically very similar and often coexist, which makes it difficult to compare their abundances. However, they are easily separated by molecular data; thus, in this work, we attempted to estimate the differences in their spatial and temporal distribution from existing metabarcoding datasets. Reanalyzing published sequences with an ASV-based pipeline and ad hoc classification routine allowed us to estimate the relative abundances of the two species, increasing the precision compared to usual OTU-based analyses. Existing data permit qualitative comparisons between two species that cannot be differentiated by other methods, detecting the distinct seasonal peaks and spatial distributions of F. radians and U. acus.

Automated summary

In this study, the abundances of two morphologically similar and coexisting diatom species, Ulnaria acus and Fragilaria radians, were compared using molecular data. By reanalyzing published sequences with an ASV-based pipeline and a specific classification routine, the relative abundances of the two species were estimated, increasing the precision compared to traditional OTU-based analyses. Existing data allowed for qualitative comparisons between these species that cannot be differentiated by other methods, revealing distinct seasonal peaks and spatial distributions of F. radians and U. acus.