Improving environmental relevance of a standard fish bioassay

The overall objective of the research conducted and described in this thesis was to develop an environmentally relevant bioassay to assess the effects of complex effluents on a sentinel fish species. A short-term fathead minnow (FHM) reproductive bioassay was utilized to assess the effects of industrial effluents on multiple levels of biological organization (sub-organismal to population endpoints). The FHM bioassay was tested in both lab and on-site investigations using an artificial stream system. The incorporation of trophic-transfer into the bioassay was also developed to quantify the importance of contaminated food as a source of exposure. This work was conducted in two key phases. Phase I focused on testing and developing the FHM bioassay, in the lab and on-site with pulp mill effluent (PME), to firstly document response patterns and, secondly, to conduct an investigation of cause study. Phase II focused on developing the trophic-transfer system to document responses to metal mine effluent (MME) in the lab and on-site in an artificial stream system. Development of the trophic-transfer system was also conducted during this phase to compare responses to standard water-only exposures. In Phase I, exposure to PME in both the lab and field studies resulted in disruptions in egg production and spawning events. By focusing on identifying response patterns I was able to determine that the effects observed were indicative of an estrogenic response. I was also able to identify a process stream that was the potential cause of responses observed after exposure to final effluent. Isolation of this process stream will assist the mill in developing approaches for future mitigation. The results from this research will also provide additional data for the environmental effects monitoring (EEM) program for pulp and paper and investigation of cause studies on a national basis. In Phase II, in both the field and laboratory investigations, significant decreases in reproductive output (egg production and spawning events) were observed in the water-only system exposures. Significant decreases in hatching success and increases in deformities were observed in the trophic-transfer system only, suggesting that the combination of both food and water was important in assessing the effects on the F1 generation. Overall, the responses in the trophic-transfer system were not comparable between the lab and field studies. In the lab study, significant decreases in reproductive output occurred, compared to the field study where significant increases in egg production and spawning events occurred. In addition, the effects on the F1 generation in the field study were not as severe as those observed in the lab investigation. It was concluded that the presence of reference water and the environment within the trophic-transfer system were responsible for this reduction in toxicity. Phases I and II of this research have made significant contributions to artificial stream development within Canada for the assessment of industrial effluents and their effects on aquatic biota. The results from these studies have also demonstrated that environmentally relevant testing is essential if we are to accurately assess effects on aquatic biota. Future development and application of this bioassay should be towards developing a standardized approach for not only assessing the effects of industrial effluents in a comparative manner, but also in investigation of cause studies