Foraging and fasting can influence contaminant concentrations in animals: an example with mercury contamination in a free-ranging marine mammal

Large fluctuations in animal body mass in relation to life-history events can influence contaminant concentrations and toxicological risk. We quantified mercury concentrations in adult northern elephant seals (Mirounga angustirostris) before and after lengthy at sea foraging trips (n = 89) or fasting periods on land (n = 27), and showed that mercury concentrations in blood and muscle changed in response to these events. The highest blood mercury concentrations were observed after the breeding fast, whereas the highest muscle mercury concentrations were observed when seals returned to land to moult. Mean female blood mercury concentrations decreased by 30% across each of the two annual foraging trips, demonstrating a foraging-associated dilution of mercury concentrations as seals gained mass. Blood mercury concentrations increased by 103% and 24% across the breeding and moulting fasts, respectively, demonstrating a fasting-associated concentration of mercury as seals lost mass. In contra...动物在生活史事件中出现的大幅体重波动，可影响污染物浓度与毒理学风险。我们对成年北象海豹（Mirounga angustirostris）在长期海上觅食之旅（n = 89）或陆地禁食期（n = 27）前后的汞浓度进行了定量检测，结果表明其血液与肌肉中的汞浓度会随这些事件发生变化。繁殖禁食后，个体血液汞浓度达到峰值；而北象海豹返回陆地换毛时，肌肉汞浓度达到最高值。雌性个体的血液汞浓度在两次年度觅食之旅中均下降了30%，表明随着象海豹体重增加，觅食行为可稀释体内汞浓度。在繁殖禁食与换毛禁食期间，血液汞浓度分别上升103%与24%，表明随着象海豹体重下降，禁食会导致体内汞浓度浓缩。In contra...