Seasonal and Regional Variations in Metal Contamination and Condition Indicators in Yellow Perch (Perca flavescens) along Two Polymetallic Gradients. III. Energetic and Physiological Indicators

ABSTRACT

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, Québec, 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.

Key Words:

• yellow perch
• metals
• metabolic capacities
• metabolic scaling
• seasonality
• regional variations

ACKNOWLEDGMENTS

This research was supported by a grant from the Metals in the Environment Research Network to PG and GP as well as by NSERC Discovery funding to PC. Renée Stewart, Joelle Violette, Patrick Busby, and Mehran Bakhtiari provided assistance with field work in Sudbury. We thank two anonymous referees for their very useful review comments.

Notes

^a p ≤ .05;

^b p ≤ .01;

^c p ≤ .001;

^d p ≤ .0001.

^a p ≤ .05;

^b p ≤ .01;

^c p ≤ .001;

^d p ≤ .0001.