Oil exposure to captive Harlequin Ducks, US Geological Survey, Alaska SeaLife Center, 2000-2002

As part of the ongoing harlequin duck studies, we conducted experiments with captive birds at the Alaska SeaLife Center to evaluate responses to oil ingestion and plumage oiling that could lend insight into mechanisms leading from oil exposure to mortality in Prince William Sound. In our captive bird experiments we found, predictably, that oil ingestion resulted in significant cytochrome P4501A induction relative to controls. The levels of induction were very similar to levels observed in wild birds, leading us to believe that results from our experiments have strong inference for understanding potential mechanisms constraining wild populations of harlequin ducks in Prince William Sound. We found that feeding and maintenance behaviors were not strongly affected by oil ingestion.
However, plumage oiling resulted in important changes to behavior; in particular, feeding activity decreased and maintenance increased with increasing plumage oiling. We suggest that the behavior changes associated with plumage oiling would not be sustainable under natural conditions and, hence, that external exposure to residual oil would most likely have significant demographic consequences, i.e. mortality.

作为丑鸭（harlequin duck）长期研究的一部分，我们于阿拉斯加海洋生物中心（Alaska SeaLife Center）对圈养个体开展实验，以评估其对原油摄入与羽毛沾油的响应，相关结果可助力阐明威廉王子湾（Prince William Sound）区域内原油暴露致死的潜在机制。在本次圈养鸭实验中，正如预期，与对照组相比，原油摄入可显著诱导细胞色素P4501A（cytochrome P4501A）的表达。该诱导水平与野生个体中观测到的水平高度吻合，由此我们认为，本实验结果可为解析威廉王子湾地区丑鸭野生种群受制约的潜在机制提供强有力的推论支撑。我们同时发现，原油摄入对取食行为与身体维护行为未产生显著影响。但羽毛沾油可引发行为的显著改变；具体而言，随着羽毛沾油程度加重，取食活动量下降，而身体维护行为频次上升。我们认为，与羽毛沾油相关的这类行为改变在自然环境中无法长期维持，因此，外源性残留原油暴露极有可能对种群动态产生显著影响，即导致个体死亡。