Griffith University , School of Environment, Southern Ocean Persistent Organic Pollutants Program (SOPOPP), QLD 4111, Australia.
Environ Sci Technol. 2013 Aug 20;47(16):9404-13. doi: 10.1021/es401441n. Epub 2013 Jul 31.
Southern hemisphere humpback whales undertake the longest migrations and associated periods of fasting of any mammal. Fluctuations in lipid energy stores are known to profoundly affect the toxicokinetics of lipophilic organochlorine compound (OC) burdens. Results from blubber biopsy sampling of adult, male humpback whales at two time points of the annual migration journey revealed dramatic concentration effects for the majority of OC compounds. The observed concentration effect was, however, not linear with measured average blubber lipid loss indicating significant redistribution of OCs and hence the importance of alternate lipid depots for meeting the energetic demands of the migration journey. Applying lipophilic OC burdens as novel tracers of whole-body lipid dynamics, the observed average concentration index suggests an average individual weight loss of 13% over 4 months of the migration journey. This value is based upon lipid derived energy and is in good agreement with previous weight prediction formulas. Notably, however, these estimates may greatly underestimate individual weight loss if significant protein catabolism occurs. Biomagnification factors between migrating southern hemisphere humpback whales and their principal prey item, Antarctic krill, closely resembled those of baleen whales feeding on herbivorous zooplankton in the Arctic. This study emphasizes the importance of considering prolonged periods of food deprivation when assessing chemical risks posed to wildlife. This is of particular importance for Polar biota adapted to extremes in ecosystem productivity.
南半球座头鲸的迁徙距离最长，在此期间也会禁食很长时间。众所周知，脂肪能量储存的波动会深刻影响亲脂性有机氯化合物（OC）负担的毒代动力学。在年度迁徙旅程的两个时间点，对成年雄性座头鲸进行的鲸脂活检采样结果表明，大多数 OC 化合物的浓度都发生了显著变化。然而，观察到的浓度效应与测量的平均鲸脂损失并不呈线性关系，这表明 OC 发生了显著再分配，因此替代脂质储存库对于满足迁徙旅程的能量需求非常重要。将亲脂性 OC 负担作为全身脂质动态的新型示踪剂，观察到的平均浓度指数表明，在 4 个月的迁徙旅程中，个体平均体重损失了 13%。这个数值基于脂肪提供的能量，与之前的体重预测公式非常吻合。然而，如果发生显著的蛋白质分解代谢，这些估计值可能会大大低估个体的体重损失。在南半球迁徙的座头鲸和它们的主要食物南极磷虾之间的生物放大因子，与在北极以草食性浮游动物为食的须鲸非常相似。这项研究强调了在评估对野生动物构成的化学风险时，必须考虑到长时间的食物匮乏期。对于适应生态系统生产力极端变化的极地生物来说，这一点尤其重要。
