Heterotrophic Bacterial Biomasses, Activities, and Productivities Within The Fraser River Plume

Abstract

Most of the microorganisms within the silt-laden Fraser River water are bacteria, the majority of which are attached to detritus and suspended silt. However, within surface water of the Strait of Georgia bacteria constitute only about 4% of the microbial biomass; most are free-living. Within the plume, which results when the freshwater of the Fraser River mixes with the seawater of the Strait of Georgia (salinity of about 27‰ and containing mainly phytoplankton) stimulations of bacterial glucose heterotrophic activity and productivity occur throughout the year. Bacterial production is a relatively greater proportion of the total microbial, i.e. both algal and bacterial production, in the winter than in the spring or fall. Preliminary evidence indicates that the stimulation of bacterial activity and productivity may be, at least partially, due to entrainment of nitrate and phosphate-rich deep water of the Strait of Georgia into the Fraser plume.Key words: Fraser plume, bacteria, production, heterotrophic activity, Strait of Georgia