Abundant and rare subcommunity 1 Aquatic ecosystems 1 Bacteria 1 Bacterial community 1 Biogeochemistry 1 Co-occurrence networks 1 Co-occurrence pattern 1 Complex networks 1 Compositional changes Environmental variations 1 Estuaries 1 Microbial interactions 1 Microeukaryotic community 1 RNA 1 Rare taxa 1 River microorganism 1 Rivers 1 Tropics 1 abundant and rare subcommunities 1 co-occurrence network 1 estuarine ecosystem 1 microbial interactions 1 river microorganisms 1