“…At large scales where aquatic ecosystems are not connected through surface freshwater, streams in separate catchments differ in many factors. Interactions between abiotic (e.g., dissolved organic matter [Judd et al, 2006], inorganic nutrients [Rubin & Leff, 2007], pH [Fierer et al, 2007], temperature [Shiah & Ducklow, 1997], redox potential [Zeng et al, 2008], seasonality [Sutton & Findlay, 2003, Santmire & Leff, 2006, Gautam et al, 2022]) and biotic (e.g., competition [Hibbing et al, 2010], predation [Thelaus et al, 2008], and viral infection [Bouvier & del Giorgio, 2007]) factors determine microbial abundance and distribution. Partially through species sorting, local habitat variations can influence community composition.…”