WA4 Indirect Effects of Stressors on Organisms and Communities
204 Oregon Ballroom
8:00 AM - 12:00 PM, Wednesday
() PCBs impair multiple physiological processes in fasted Arctic charr leading to reduced fitness.
Maule, A1, Jorgensen, E2, Vijayan, M3, Killie, J2, Aas-Hansen, O2, Aluru, N3, 1 USGS, WFRC Columbia River Research Lab, Cook, WA, USA2 Norwegian College of Fisheries Science, University of Tromso, Tromso, Norway3 Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
ABSTRACT- Polychlorinated biphenyls (PCB) enter the Arctic environment by aerial transport from industrialized nations, and bio-magnify in the aquatic food web. Some anadromous Arctic charr feed in the ocean for 6 to 8 wks, accumulate PCBs, and then fast during the winter in freshwater. In ecologically relevant studies, we investigated the effects of PCBs and nutritional status on organ function and performance critical to charr survival. Charr were contaminated orally with Aroclor 1254 and held with or without food for 5 months. Fasted fish were given 0, 1, 10 or 100 mg PCB kg-1and the fed fish 0 or 100 mg PCB kg-1. Stress response: Fasted control fish had elevated resting plasma cortisol levels compared to fed fish; however, PCBs suppressed the fasting-mediated elevation of plasma cortisol in Arctic charr. Also, the stress-induced cortisol response was completely hampered in fish administered the high PCB dose, clearly pointing to an abnormal functioning of the hypothalmic-pituitary-interrenal axis. Disease resistance: Fish were exposed to the pathogen Aeromonas salmonicida (the causative agent of furunculous). Fasted fish with progressively higher PCB contamination had progressively higher mortality, ranging from 32% to 55%. PCBs had no effect on disease resistance of fed fish. PCBs also reduced the innate immune response in Arctic charr. Lysozyme activity in skin mucous of all treatment fish was significantly lower than that of control fish, and plasma lectin activity was reduced in PCB-treated fish in a dose-related manner. Saltwater adaptation: Charr in the high PCB group had transient or permanent reductions in several hormones important during smoltification. The hormonal alterations corresponded with impaired hyposmoregulatory ability, and reduced growth rate and survival in seawater. Consequently, fewer fish in the high PCB group matured compared to the other treatments. We conclude that PCBs impair physiological functioning and performance, resulting in reduced fitness. Such effects will have serious consequences for charr populations.
Key words: polychlorinated biphenyls, arctic charr, physiology, fitness