The overall objective of this research project was to assess whether fish populations in areas of potato cultivation responded to changes in environmental conditions. An effects-based assessment was conducted in the ‘potato belt’ of northwestern New Brunswick in the Little River catchment. From 1999-2001, the health and performance of slimy sculpin (Cottus cognatus) was monitored in agricultural and forested sections of the river. In the fall of 1999 and 2000, agricultural sites had fewer young-of-the-year (YOY) sculpin than the forested region. Adult sculpin were larger in the agricultural region, but had significantly smaller gonads, and female sculpin had smaller livers, and fewer and smaller eggs than the forested region. By the fall of 2001, only female gonad size showed a difference from the forested region. These results were used to design a follow-up study designed to investigate the relative importance of environmental factors influencing sculpin responses. <br><br> The second study investigated the relative influence of temperature and sediment deposition on slimy sculpin populations across 20 sites on 19 streams in forested and agricultural catchments in northwestern New Brunswick. YOY sculpin were present at all forested sites, but only at 2 of 11 agricultural sites. There were no relationships between body size or density and sediment deposition in either the agricultural or forested regions, but sculpin density decreased and median YOY size increased with increasing temperatures. The variability in density of YOY sculpin at agricultural sites suggested that additional factors beyond temperature might be contributing to responses. <br><br> A secondary overall objective was to evaluate the slimy sculpin as a sentinel and indicator of site-specific conditions. Stable isotopes of muscle tissues showed little variability in isotopic signatures, and significant differences between adjacent sites. Passive integrated transponder (PIT) tags implanted in 112 adult sculpin showed that 75% of sculpin captured over 10 months moved less than 30m. Both isotopes and PIT tags suggested high spatial and temporal residency of slimy sculpin. <br><br> This PhD project showed biological impacts on sculpin populations residing in streams influenced by non-point source agricultural stressors, and provided support for the ability of the slimy sculpin to reflect local environmental conditions.

The overall objective of my thesis research was to develop methodologies for assessing effects of mining effluents on pristine and sensitive northern rivers. I used a multi-trophic level approach in field studies to evaluate current monitoring methods and to determine whether metal mining activities had affected two otherwise pristine rivers that flow into the South Nahanni River, NWT; a World Heritage Site. Upstream reference conditions in the rivers were compared to sites downstream and further downstream of mines. The endpoints evaluated included concentrations of metals in river water, sediments and liver and flesh of slimy sculpin (Cottus cognatus); benthic algal and macroinvertebrate abundance, richness, diversity, and community composition; and various slimy sculpin measures. Elevated concentrations of copper (p=0.002)and iron (p=0.001) in liver tissue of sculpin from the Flat River were associated with high concentrations of mine-derived iron in river water and copper in sediments that were above national guidelines. In addition, sites downstream of the mine on the Flat River had increased algal abundances (p=0.002) and altered benthic macroinvertebrate communities ((p<0.001) whereas the sites downstream of the mine on Prairie Creek had increased benthic macroinvertebrate taxa richness (p=0.050) and improved sculpin condition (males: p=0.008; females: p=0.001). Biological differences in both rivers were consistent with mild enrichment of the rivers downstream of current and historical mining activity. Although the effects of mining activities on riverine biota in these northern rivers are currently limited, results of this research show that there is potential for effects to occur with proposed growth in mining activities.<p> Laboratory exposures were conducted using slimy sculpin, identified as a sentinel fish species in pristine northern rivers, to identify alternative methods for assessing toxicity of contaminants of concern in mining effluents. Ammonia was selected for the exposures based on effluent characteristics of northern mining effluents. Ammonia is known to be an important toxicant in aquatic environments. Although ammonia toxicity has been well studied in many fish species, effects of chronic exposure of slimy sculpin, a critical biomonitoring species for northern aquatic habitats, are not well known. Slimy sculpin were exposed to six concentrations of un-ionized ammonia relevant to concentrations found in northern mining effluents: control (0 ppm), 0.278 ppm, 0.556 ppm, 0.834 ppm, 1.112 ppm, and 1.668 ppm. An LC50 of 1.529 ppm was calculated from mortality data. Histopathological examination of gills indicated significant tissue damage, measured as lamellar fusion and epithelial lifting, at 0.834, 1.112, and 1.668 ppm. Using gill endpoints, NOEC and LOEC were calculated as 0.556 ppm and 0.834 ppm respectively. An EC50 of 0.775 ppm was determined for lamellar fusion and an EC50 of 0.842 ppm for epithelial lifting. Hemorrhage of gills was present in mortalities which occurred at 1.668 ppm of un-ionized ammonia. A significant decrease in liver somatic index (LSI) was seen in both male and female fish at 0.834 and 1.112 ppm, respectively. Gonadosomatic index (GSI) in female fish significantly increased at 1.668 ppm un-ionized ammonia with an associated significant increase in total whole body testosterone concentrations. GSI in male fish also significantly increased at 1.668 ppm but no differences were seen in testosterone concentrations. No significant differences were seen in gonad histopathological assessments or condition factor. Results from this study indicate that ammonia concentrations commonly reported in northern mine effluents hold potential to affect the health of slimy sculpin including acute, chronic, histological and endocrine endpoints. <p> Results from both the field study and laboratory exposures provide direction for future monitoring programs in pristine northern rivers and emphasize the importance of monitoring tools to detect change in these ecosystems. I recommend that monitoring of northern pristine rivers focus on a multi-trophic monitoring approach including indicators in algal and benthic macroinvertebrate communities due to their responsiveness. Laboratory exposures using slimy sculpin should be considered to obtain toxicological information for northern contaminants of concern. Gill histopathology endpoints may be a more sensitive indicator for detecting effects in slimy sculpin exposed to ammonia than traditional chronic endpoints. I also recommend monitoring of metal burdens in periphyton and benthic invertebrates for assessment of exposure to mine effluent and causal association in areas of low fish abundance.

The overall objective of my thesis research was to develop methodologies for assessing effects of mining effluents on pristine and sensitive northern rivers. I used a multi-trophic level approach in field studies to evaluate current monitoring methods and to determine whether metal mining activities had affected two otherwise pristine rivers that flow into the South Nahanni River, NWT; a World Heritage Site. Upstream reference conditions in the rivers were compared to sites downstream and further downstream of mines. The endpoints evaluated included concentrations of metals in river water, sediments and liver and flesh of slimy sculpin (Cottus cognatus); benthic algal and macroinvertebrate abundance, richness, diversity, and community composition; and various slimy sculpin measures. Elevated concentrations of copper (p=0.002)and iron (p=0.001) in liver tissue of sculpin from the Flat River were associated with high concentrations of mine-derived iron in river water and copper in sediments that were above national guidelines. In addition, sites downstream of the mine on the Flat River had increased algal abundances (p=0.002) and altered benthic macroinvertebrate communities ((p<0.001) whereas the sites downstream of the mine on Prairie Creek had increased benthic macroinvertebrate taxa richness (p=0.050) and improved sculpin condition (males: p=0.008; females: p=0.001). Biological differences in both rivers were consistent with mild enrichment of the rivers downstream of current and historical mining activity. Although the effects of mining activities on riverine biota in these northern rivers are currently limited, results of this research show that there is potential for effects to occur with proposed growth in mining activities.<p> Laboratory exposures were conducted using slimy sculpin, identified as a sentinel fish species in pristine northern rivers, to identify alternative methods for assessing toxicity of contaminants of concern in mining effluents. Ammonia was selected for the exposures based on effluent characteristics of northern mining effluents. Ammonia is known to be an important toxicant in aquatic environments. Although ammonia toxicity has been well studied in many fish species, effects of chronic exposure of slimy sculpin, a critical biomonitoring species for northern aquatic habitats, are not well known. Slimy sculpin were exposed to six concentrations of un-ionized ammonia relevant to concentrations found in northern mining effluents: control (0 ppm), 0.278 ppm, 0.556 ppm, 0.834 ppm, 1.112 ppm, and 1.668 ppm. An LC50 of 1.529 ppm was calculated from mortality data. Histopathological examination of gills indicated significant tissue damage, measured as lamellar fusion and epithelial lifting, at 0.834, 1.112, and 1.668 ppm. Using gill endpoints, NOEC and LOEC were calculated as 0.556 ppm and 0.834 ppm respectively. An EC50 of 0.775 ppm was determined for lamellar fusion and an EC50 of 0.842 ppm for epithelial lifting. Hemorrhage of gills was present in mortalities which occurred at 1.668 ppm of un-ionized ammonia. A significant decrease in liver somatic index (LSI) was seen in both male and female fish at 0.834 and 1.112 ppm, respectively. Gonadosomatic index (GSI) in female fish significantly increased at 1.668 ppm un-ionized ammonia with an associated significant increase in total whole body testosterone concentrations. GSI in male fish also significantly increased at 1.668 ppm but no differences were seen in testosterone concentrations. No significant differences were seen in gonad histopathological assessments or condition factor. Results from this study indicate that ammonia concentrations commonly reported in northern mine effluents hold potential to affect the health of slimy sculpin including acute, chronic, histological and endocrine endpoints. <p> Results from both the field study and laboratory exposures provide direction for future monitoring programs in pristine northern rivers and emphasize the importance of monitoring tools to detect change in these ecosystems. I recommend that monitoring of northern pristine rivers focus on a multi-trophic monitoring approach including indicators in algal and benthic macroinvertebrate communities due to their responsiveness. Laboratory exposures using slimy sculpin should be considered to obtain toxicological information for northern contaminants of concern. Gill histopathology endpoints may be a more sensitive indicator for detecting effects in slimy sculpin exposed to ammonia than traditional chronic endpoints. I also recommend monitoring of metal burdens in periphyton and benthic invertebrates for assessment of exposure to mine effluent and causal association in areas of low fish abundance.

To assess potential impacts of effluents from Key Lake and McClean Lake uranium operations on freshwater systems, morphometric (weight, length, condition factor) and biochemical (total body lipids and triglycerides, liver triglycerides, muscle protein, muscle RNA/DNA ratio) measures of growth and bioenergetics were determined in young-of-the-year (YOY) fishes collected in fall and spring. It was predicted that fishes exposed to mining and milling effluents would be in poorer condition relative to fishes from reference sites and that fishes would be depleted in lipids and triglycerides in the spring compared to the previous fall following a northern winter. Various total body lipid and triglyceride measurement methods were initially compared and validated. <p>Lakes receiving effluent at Key Lake (in operation > 20 years) were higher in metals, ions and ammonia compared to exposure sites at McClean Lake (in operation < 10 years). At Key Lake, there were site and season differences in total body lipids and triglycerides in YOY northern pike (<i>Esox lucius</i>) and burbot (Lota lota), with fishes being fattier at exposure sites compared to fishes at the reference site, and fish being fattier in spring relative to fall. A local prey item, spottail shiners (<i>Notropis hudsonius</i>), from an exposure lake were higher in triglycerides compared to shiners from a reference site, suggesting an indirect effect of uranium operation effluent on pike and burbot bioenergetics via food web enrichment. At McClean Lake, there were site and season increases in lipids and triglycerides in burbot from the exposure site, however there were no site differences in any morphometric or biochemical endpoint for northern pike. Slimy sculpin (<i>Cottus cognatus</i>) were the only species with lower triglyceride content in the spring following winter. <p>Overall, biochemical measures of growth (muscle protein, muscle RNA/DNA ratio) did not vary with effluent exposure at either uranium operation. Lipids and triglycerides were useful biochemical endpoints that frequently detected site and season differences in fish condition that were not noted with morphometric measures. Site and season differences in fish lipids and triglycerides at sites receiving mining and milling effluents revealed an impact of the uranium operations on indigenous YOY fish condition.

To assess potential impacts of effluents from Key Lake and McClean Lake uranium operations on freshwater systems, morphometric (weight, length, condition factor) and biochemical (total body lipids and triglycerides, liver triglycerides, muscle protein, muscle RNA/DNA ratio) measures of growth and bioenergetics were determined in young-of-the-year (YOY) fishes collected in fall and spring. It was predicted that fishes exposed to mining and milling effluents would be in poorer condition relative to fishes from reference sites and that fishes would be depleted in lipids and triglycerides in the spring compared to the previous fall following a northern winter. Various total body lipid and triglyceride measurement methods were initially compared and validated. <p>Lakes receiving effluent at Key Lake (in operation > 20 years) were higher in metals, ions and ammonia compared to exposure sites at McClean Lake (in operation < 10 years). At Key Lake, there were site and season differences in total body lipids and triglycerides in YOY northern pike (<i>Esox lucius</i>) and burbot (Lota lota), with fishes being fattier at exposure sites compared to fishes at the reference site, and fish being fattier in spring relative to fall. A local prey item, spottail shiners (<i>Notropis hudsonius</i>), from an exposure lake were higher in triglycerides compared to shiners from a reference site, suggesting an indirect effect of uranium operation effluent on pike and burbot bioenergetics via food web enrichment. At McClean Lake, there were site and season increases in lipids and triglycerides in burbot from the exposure site, however there were no site differences in any morphometric or biochemical endpoint for northern pike. Slimy sculpin (<i>Cottus cognatus</i>) were the only species with lower triglyceride content in the spring following winter. <p>Overall, biochemical measures of growth (muscle protein, muscle RNA/DNA ratio) did not vary with effluent exposure at either uranium operation. Lipids and triglycerides were useful biochemical endpoints that frequently detected site and season differences in fish condition that were not noted with morphometric measures. Site and season differences in fish lipids and triglycerides at sites receiving mining and milling effluents revealed an impact of the uranium operations on indigenous YOY fish condition.