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National Assessment of Pulp and Paper Environmental Effects Monitoring Data: Findings from Cycles 1 through 3

Abstract

Under the Fisheries Act, Canadian pulp and paper mills are required to conduct Environmental Effects Monitoring (EEM) to assess effects potentially caused by their effluents. This report presents the results of the national assessment of EEM data collected from the receiving environments of pulp and paper mills across Canada for Cycles 1 through 3 (covering the years 1992-2004), with particular emphasis on the last four years (Cycle 3). The field survey response patterns observed for effluent-exposed fish and benthic invertebrates have, for the most part, shown a high degree of consistency through time over the last two cycles of data collection. The national average response pattern measured for fish in both Cycles 2 and 3 was one typically associated with nutrient enrichment overlaid by metabolic disruption. That is, exposed fish have consistently shown evidence of increased food availability or increased food absorption (fatter, faster growing, with larger livers) together with disruption of allocation of resources to reproduction (smaller gonads). The national average response for benthic invertebrate communities in both Cycles 2 and 3 was indicative of eutrophication, ranging from mild to more pronounced, partly depending on habitat type. More specifically, benthic invertebrate communities exposed to pulp mill effluent have commonly exhibited increases in abundance, together with some combination of increases, decreases or no change in taxon richness, depending on the degree of eutrophication. For both the fish and benthic invertebrate field surveys, other response patterns were also observed at some mills; furthermore, some possible shifts in patterns of effects were observed between Cycles 2 and 3, but these shifts were mostly relatively small. The results obtained in Cycle 4 and beyond, together with more focused studies at some mills, will help to address the biological significance (if any) of these shifts. The sublethal toxicity data showed clear improvements in effluent quality from Cycle 1 to Cycle 2, with, for the most part, no further changes in effluent quality in Cycle 3. Based on critical effect sizes developed for the fish and benthic invertebrate field survey endpoints, initial estimates are that approximately 20% of the monitored mills are expected to conduct only sublethal toxicity testing in Cycle 4, while roughly another 20% are expected to progress to determinations of the extent and magnitude of effects or, for some mills, investigations of the causes of the effects. Previous to the EEM program, a broad view of pulp and paper mill effluent effects on aquatic biota was not available at a national level in Canada (or, at this geographic scale, in other jurisdictions). The extensive database generated by the EEM program, and the subsequent analyses, have provided a fairly robust picture of the effects of these effluents on receiving waters across the country.