Pyle, Greg

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https://opus.uleth.ca/handle/10133/3438

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Browsing Pyle, Greg by Author "Rajotte, James W."

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    Seasonal and regional variations in metal contamination and condition indicators in yellow perch (Perca flavescens) along two polymetallic gradients. II. Growth patterns, longevity, and condition
    (Taylor & Francis, 2008) Pyle, Gregory; Busby, Patrick; Gauthier, Charles; Rajotte, James W.; Couture, Patrice
    Wild yellow perch (Perca flavescens) were sampled from five lakes in each of two metal contamination gradients in Sudbury, Ontario, Canada (n = 1324) and Rouyn- Noranda, Qu´ebec, Canada (n = 1125) in the spring and summer of 2002 and 2003, respectively, in order to examine growth patterns, longevity, and the influences of season and region on fish condition. Fish from Rouyn-Noranda began rapid growth at a young age, whereas fish from Sudbury lakes showed slow growth rates between ages 0–3, after which growth rates improved. Fish from contaminated lakes grew faster and died younger than fish from reference lakes in both contamination gradients. Fish from Sudbury had lower condition than in Rouyn-Noranda, higher condition occurred in summer than spring, and fish from contaminated lakes had lower condition than those from cleaner lakes. Tissue Zn concentrations were correlated with fish condition and showed strong temporal stability. However, it is more likely that Zn covariates, such as Cd or Cu (which were more temporally variable) influenced condition, suggesting that long-term, broad-scale processes are more important than short-term, lake-specific processes for establishing growth patterns, longevity, and fish condition in metal-contaminated systems. Results from this study reveal that fish condition must be interpreted in the light of regional, seasonal, and other factors that can potentially influence fish growth patterns. Ecological risk assessments that fail to take these factors into account may draw erroneous conclusions about risk to indigenous populations.
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    Seasonal and regional variations in metal contamination and condition indicators in yellow perch (Perca flavescens) along two polymetallic gradients. III. Energetic and physiological indicators
    (Taylor & Francis, 2008) Couture, Patrice; Rajotte, James W.; Pyle, Gregory
    The influences of metal contamination, fish size, season, and region on tissue metabolic capacities and protein concentrations were examined in yellow perch from two metal gradients (Sudbury, Ontario, and Rouyn-Noranda, Qu´ebec, Canada) in two seasons (spring and summer). In general, increased tissue Cu and Cd contamination was associated with lower aerobic capacities, suggesting direct metal inhibition of aerobic enzymes. However, our data also revealed that tissue Ni contamination positively affected aerobic capacities, possibly due to oxidative damage to mitochondrial membranes leading to compensatory increases in the activity of mitochondrial enzymes. Tissue aerobic capacities decreased, but anaerobic capacities increased, with size. Tissue protein concentrations and metabolic capacities were also influenced by season. A novel finding of this study is that size-corrected tissue enzyme activities can differ markedly in yellow perch sampled in the same season in similar lakes, but separated by a few hundred kilometers. Overall, the results from this large dataset support that tissue metabolic capacities are under seasonal and regional influences, but are also affected by metal contamination. Our study indicates that tissue metabolic enzyme activities should be considered as a tool for ecological risk assessment studies aiming at detecting metal stress in wild fish. However, fish should be sampled over a short period, and reference sites should be close to contaminated sites
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    Seasonal and regional variations of metal contamination and condition indicators in yellow perch (Perca flavescens) along two polymetallic gradients. I. Factors influencing tissue metal concentrations
    (Taylor & Francis, 2008) Couture, Patrice; Busby, Patrick; Gauthier, Charles; Rajotte, James W.; Pyle, Gregory
    This study examined relationships among water, sediment, diet, and fish tissue metal (Cd, Cu, Ni, Se, and Zn) concentrations in yellow perch from metal gradients in two regions (Sudbury (S), Ontario, and Rouyn-Noranda (RN), Qu´ebec, Canada) in two seasons (spring and summer). The objectives of this study were (1) to examine the influences of aqueous and dietary metal contamination on yellow perch liver and kidney metal accumulation; (2) to compare the seasonal and regional variations in gut content and tissue metal concentrations along the two gradients studied; and (3) to investigate the potential of metals for tissue accumulation under conditions of life-long chronic exposure. Our results suggest a greater aqueous than dietary influence on tissue metal concentrations for all metals examined except Cd, where the opposite was observed. Metals did not accumulate in older fish, except for Cd that accumulated with age in RN, but not S, fish. Regional, but also metal-specific differences in metal handling capacities are proposed. Fish from neither region appeared capable of regulating tissue Cd concentrations, but fish from both regions regulated Zn tightly. Sudbury fish appeared better at regulating tissue Cu, Ni, and perhaps also Se concentrations than RN fish, suggesting acclimation or selection for metal tolerance. There were several significant seasonal effects on tissue metal concentrations. However, close examination of the dataset does not allow proposing the presence of a season-linked mechanism explaining these variations, precluding a modeling approach and implying that repeat sampling within and among years is required for proper ecological risk assessment.