Sestonic bacterial nutrient limitation in a northern temperate river and the impact of pulp-mill effluents

Bacterial growth limitation and the effect of pulp-mill effluents (PME) on sestonic bacteria were studied in a northern temperate river (the Fraser River, British Columbia, Canada). Nutrient addition experiments demonstrated that sestonic bacterial growth was potentially limited by P. Experiments were done by adding N, P, or organic carbon to 21 microcosms of river water, The addition of P (singly, and in combination with N and C) increased bacterial production (rate of H-3-thymidine incorporation) and activity (C-14-glucose uptake), while the addition of N or organic carbon did not. The inflow of PME into the Fraser River increased bacterial abundance, activity, and production in 2 ways. First, P in the PME increased native bacterial abundance and processes, and second, PME provided a source of active bacteria to the river.