Using Demographic Analyses to Evaluate the Impact of Man-made Disasters on Imperiled Species: Piping Plovers and the Deepwater Horizon Oil Spill

Even in the presence of environmental safeguards, catastrophic accidents related to anthropogenic activities occur that can result in both immediate and chronic impacts on local biota. However, due to the unplanned nature of catastrophes, studies aimed to identify the effects of these accidents on an ecosystem and its inhabitants often have imperfect study designs that are reactive rather than proactive, resulting in methodological and analytical challenges. On 20 April 2010, following an explosion on the Deepwater Horizon, a well blowout occurred on the seafloor approximately 80 km off the Louisiana coast in the Gulf of Mexico. This blowout resulted in the largest marine oil spill in United States history, which impacted critical migratory stopover and overwintering habitat for many seabird and shorebird species, including species of high conservation concern such as the piping plover (Charadrius melodus). Here, we assessed the potential short-term and carry-over demographic impacts of the Deepwater Horizon oil spill on piping plovers in a capture-mark-recapture framework. We examined whether a series of demographic processes, including probabilities of remaining at a specific wintering site, over-winter and annual apparent survival, winter stopover duration, and abundance varied among oiled and unoiled habitats. We found that the perceived amount of oiling on land, in water, and on individual birds, as well as numerous demographic processes, were spatially or temporally variable. However, we found no support that piping plover demography was negatively influenced by the magnitude of oil observed at an impacted area, or that demographic rates substantially varied between reference and oil impacted areas. Nor did we find that piping plovers that were observed to be oiled had lower survival probabilities following the DWH oil spill relative to non-oiled individuals from the same winter population. Although we did not find that the Deepwater Horizon oil spill substantially influenced piping plovers, our methods provide an analytical framework to more appropriately address both the short or long-term impacts of an anthropogenic disturbance on a species.Data from:Gibson, D., D.H. Catlin, K.L. Hunt, J. D. Fraser, S. Karpanty, M.J. Friedrich, M.K. Bimbi, J. B. Cohen, and S.B. Maddock (in review). Using Demographic Analyses to Evaluate the Impact of Man-made Disasters on Imperiled Species: Piping Plovers and the Deepwater Horizon Oil Spill

即便配备了环境防护措施，由人为活动引发的灾难性事故仍时有发生，此类事故可对当地生物群落造成即时与慢性的双重损害。鉴于灾难的突发性，旨在揭示此类事故对生态系统及其栖息生物影响的相关研究，往往因采用事后响应式而非前瞻性设计而存在先天缺陷，进而带来方法学与分析层面的诸多挑战。2010年4月20日，深水地平线（Deepwater Horizon）钻井平台发生爆炸后，墨西哥湾距路易斯安那州海岸约80公里的海底发生井喷事故。此次井喷引发了美国历史上规模最大的海上石油泄漏事件，严重破坏了众多海鸟与滨鸟物种的关键迁徙中途停歇地与越冬栖息地，其中包括受保护关注度较高的物种，如笛鸻（piping plover, Charadrius melodus）。本研究采用标记重捕法（capture-mark-recapture）框架，评估了此次深水地平线石油泄漏事件对笛鸻种群可能造成的短期及遗留种群动态影响。我们分析了一系列种群统计过程的差异，包括特定越冬居留概率、越冬及年度表观存活率、冬季中途停歇时长，以及种群丰度在受油污染与未受油污染栖息地间的变化情况。研究结果显示，陆地、水体及个体鸟类上的可见油污程度，以及诸多种群统计过程，均存在空间或时间异质性。然而，我们并未发现证据表明，受影响区域的油污程度会对笛鸻的种群动态产生负面影响，也未发现参考区域与受油污染区域间的种群统计参数存在显著差异。此外，相较于同一越冬种群中未沾染油污的个体，被观测到沾染油污的笛鸻在泄漏事件后的存活率并未更低。尽管本研究未发现深水地平线石油泄漏事件对笛鸻种群造成显著影响，但其所采用的分析框架，可为更为精准地评估人为干扰对物种的短期或长期影响提供重要参考。数据来源：Gibson, D., D.H. Catlin, K.L. Hunt, J. D. Fraser, S. Karpanty, M.J. Friedrich, M.K. Bimbi, J. B. Cohen, 及S.B. Maddock（审稿中）. 《利用种群统计分析评估人为灾害对濒危物种的影响：以笛鸻与深水地平线石油泄漏事件为例》