Junyao Gu

Phytoplankton form the base of aquatic food webs, drive primary production, and serve as bioindicators of ecosystem health. However, the mechanisms regulating their biodiversity and how their biodiversity regulates ecosystem functioning in river ecosystems, particularly large rivers like the Danube River, remain poorly resolved. While environmental filtering and zooplankton grazing are known drivers of phytoplankton dynamics, there is a lack of detailed evidence in the riverine ecosystem. Furthermore, most previous studies have focused on broad phylogenetic levels (e.g., whole community), overlooking fine- scale taxonomic diversity (e.g., operational taxonomic units, OTUs), which recent research suggests plays a crucial role in maintaining microbial community stability over time and space.

Here, my proposed research will employ a multitrophic approach to investigate phytoplankton-zooplankton interactions and their dynamics at fine taxonomic resolution under a changing environment in large river ecosystems. By integrating expertise in community ecology, bioinformatics, Bayesian modelling, and microbial interactions, this project will study how microdiversity-mediated multiple trophic interactions (phytoplankton-zooplankton) drive the biodiversity-ecosystem functioning relationship in the Danube River. These insights are critical for predicting river ecosystem responses to human disturbance and global warming, and for guiding sustainable river management.