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

Abstract

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 (O ppt 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 ppt S). Bacteria, both attahced 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 ppt. 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.