Contrasting patterns of free-living bacterioplankton diversity in macrophyte-dominated ver

Contrasting patterns of free-living bacterioplankton diversity in macrophyte-dominated versus phytoplankton blooming regimes in Dianchi Lake, a shallow lake in China*

WANG Yujing (王毓菁) 1,2, LI Huabing (李化炳) 1, XING Peng (邢鹏) 1,**,WU Qinglong (吴庆龙) 1,3,**

【摘 要】Abstract Freshwater shallow lakes typically exhibit two alternative stable states under certain nutrient loadings: macrophyte-dominated and phytoplankton-dominated water regimes. An ecosystem regime shift from macrophytes to phytoplankton blooming typically reduces the number of species of invertebrates and fish es and results in the homogenization of communities in freshwater lakes. We investigated how microbial biodiversity has responded to a shift of the ecosystem regime in Dianchi Lake, which was previously fully covered with submerged macrophytes but currently harbors both ecological states. We observed marked divergence in the diversity and community composition of bacterioplankton between the two regimes.Although species richness, estimated as the number of operational taxonomic units and phylogenetic diversity (PD), was higher in the phytoplankton dominated

ecosystem

after

this

shift,

the

dissimilarity

of

bacterioplankton community across space decreased. This decrease in beta diversity was accompanied by loss of planktonic bacteria unique to