Proceedings - Teaching and Learning Centre - Simon Fraser ...

Fraser River Action Plan 3rd Research Workshop
Effects of Pulp Mill Effluent on Benthic Communities
in the Upper Fraser and Lower Thompson River Systems
J.M. Culp, K.J. Cash and R.B. Lowell
National Hydrology Research Institute
Experimentation using field-based artificial streams provides a promising, complimentary approach to
biomonitoring assessments because artificial streams provide control over relevant environmental variables and
true replication of treatments.
We have used large and small artificial stream systems, based in the field, to examine the effect of treated
bleached Kraft pulp mill effluent (BKME) on the benthos of the Fraser and Thompson rivers. Under natural
regimes of temperature, water chemistry and insolation, these artificial streams provide current velocities and
substrata to food chains or food webs that are representative of those in the study river. With these tools, we
have shown that BKME treatments increased algal biomass and invertebrate density in the Fraser River. While
BKME treatments did not change diatom species richness or diatom species diversity, insect familial richness in
the Fraser River was reduced by exposure to 1% and 3% BKME.
In the Thompson River, BKME stimulated mayfly growth above that which could be accounted for by
fertilization of their algal food supply. In contrast, moulting frequency was inhibited at high BKME
concentrations. Results from the Thompson River artificial stream experiments also indicated that increased
algal biomass and abundances of benthic invertebrates downstream of BKME outfalls were induced by nutrient
enrichment from the effluent. Our experimental results helped to explain long-term (20-year) patterns in
invertebrate community structure in the Thompson River and provided the opportunity to examine the effect on
environmental assessments of using different sampling frequencies (one to three per year) for environmental
effects monitoring (EEM) programs.
Conclusions
In summary, the integration of field monitoring data with results from artificial stream experiments provides a
means of understanding the mechanisms of stressor effects over a continuum ranging from single stressor effects
on specific taxa to the effects of multiple stressors on communities and ecosystems.
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