Attached and Free-Floating Bacteria in the Fraser River Estuary, British Columbia, Canada

The contribution of free-floating bacteria versus bacteria attached to particulate material to the microbiology of the Fraser River Estuary was assessed. Approximately 60 % of bacterial biomass and heterotrophic activity was associated with suspended particulates in the turbid Fraser River (0 Y&o S). The influence of attached bacteria decreased down the estuary as salinity increased dropping to 15-39 % of total bacterial numbers and 4 % of heterotrophic activity in the Strait of Georgia (26 Ym S). Bacteria, both attached and free-floating, were the predominant part of the microbial population in the river in terms of biomass and productivity. In the Strait of Georgia, however, bacteria constituted only 4 % of the microbial biomass and 25 % of microbial productivity. Heterotrophic activity and productivity were stimulated in the plume (15 % S) to levels higher than those found in either the strait or the river. The percentage glucose respired was always found to be lowest in the river.