Page 978 - The Toxicology of Fishes

958 The Toxicology of Fishes

collection of data, PME effects assessment is no longer focused on how to measure effects but has
progressed to a stage of determining which effects are ecologically important (Munkittrick et al., 2000a).
One of the major factors limiting progress with regard to the interpretation of effects is the miscon-
ception that all impacts are adverse, and therefore are unacceptable. As Munkittrick et al. (2000b) pointed
out, individuals can survive numerous biochemical impacts, and populations can survive numerous
individual impacts. Effects need to be evaluated with appropriate perspective and in the context of
sustainable development. Consideration of the magnitude of a change and the consistency of a change
among indicators (e.g., liver size and condition in fish) and across trophic levels (e.g., benthos and fish
effect indicators) will be critical to assist with assessing the importance of a change. The use of power
analyses to develop confidence in a measured change will also be an important component to the
assessment process. Determining the extent to which the change is relative to natural variability measured
at reference sites is also important.
National-scale monitoring programs have provided invaluable information on the types of response
patterns observed in receiving environments exposed to PMEs and the magnitude of the changes across
mills (Environment Canada, 2003; Lowell et al., 2004). This information provides an industrywide
picture to evaluate what the dominant responses are and where responses are of the greatest magnitude.
These data are also serving to advance our understanding of critical biological effect sizes.
Finally, it will be necessary to evaluate changes in receiving environment quality due to PME exposure
relative to other natural and manmade influences to assess the importance of PME effects. Effective
management of aquatic systems requires a holistic understanding of changes resulting from the accu-
mulation of stressor types, including land use, other industrial discharges, urbanization, and climate
change. Cumulative effects assessment approaches at watershed and regional scales such as those
proposed by Culp et al. (2000), Munkittrick et al. (2000b), and Dubé (2003) may provide advancement
in this area. In Sweden, decisions on environmental quality objectives may be based on ethical concerns
and public perceptions and not strictly on ecological relevance (Environmental Sweden, 1997). It is the
responsibility of the scientific process to objectively quantify and provide information on the types of
changes, the distribution of changes, the frequency and duration of changes, and the relevance of changes
to other levels of organization so that this information can be used to make more informed decisions.

Conclusions
Over the past 30 years, examination of the effects of PMEs on fish has advanced our understanding of
fish toxicology and has increased our awareness of the issues of managing aquatic ecosystems receiving
industrial effluent discharges. Historically, pulp and paper effects on fish were documented, regulations
were implemented, and the industry responded with process changes and effluent management to
significantly improve effluent quality and reduce the effects of effluents on wild fish. As a result of the
culmination of studies, new monitoring techniques and biochemical endpoints have been developed over
the years to better assess effluent effects. Currently, research focuses on identification of mill sources
and causative compounds that may be contributing to residual effects of mill effluent on fish reproduction
at some mill sites. In addition, research is being conducted to develop decision-making frameworks for
improved integration of effects-based science with management issues pertaining to pulp and paper
effects assessment for aquatic ecosystems.

References

Aaltonen, T. M., Jokinen, E. I., and Lappivaara J. (2000a). Effect of primary and secondary-treated bleached
kraft mill effluents on the immune system and physiological parameters of roach. Aquat. Toxicol., 51,
55–67.
Aaltonen, T. M., Jokinen, E. I., and Salo, H. M. (2000b). Modulation of immune parameters of roach, Rutilus
rutilus, exposed to untreated ECF and TCF bleached pulp effluents. Aquat. Toxicol., 47, 277–289.