Ecology Department, Montana State University, Bozeman, MT, 59715, USA.
R.G. Ford Consulting Company, 2735 N.E. Weidler Street, Portland, OR, 97232, USA.
Environ Monit Assess. 2020 Mar 17;191(Suppl 4):813. doi: 10.1007/s10661-019-7919-9.
During a marine oil spill, injured birds often die on the water, some eventually washing ashore, but others becoming waterlogged and sinking or being scavenged before reaching the shoreline. Birds that disappear before they can be deposited on the shoreline are difficult to enumerate, but they commonly represent a large fraction of total oil spill-related mortality. As part of the process of quantifying the overall impact to seabirds resulting from the Deepwater Horizon oil spill, it was necessary to estimate the number of dead birds lost at sea. We conducted a study to estimate the beaching probability of birds that died at sea in the Gulf of Mexico in the areas most heavily used by seabirds and impacted by the spill. Using a mark-recapture analysis to derive the beaching probability from our field study data, we estimated that dead birds afloat at sea had about a 0.1414 probability of beaching in areas searched during the Deepwater Horizon oil spill. Sensitivity analyses of our model and requisite assumptions suggested that if our assumptions were violated, the "true" beaching probability could be anywhere between 0.11 and 0.16. These estimates are much lower than beaching probabilities estimated for seabirds killed during the Exxon Valdez oil spill in the waters of Alaska, for example, likely reflect higher rates of decomposition and scavenging in the warmer waters of the Gulf of Mexico. Our estimate suggests that bird carcasses that washed onshore during the Deepwater Horizon oil spill represented only 14% of those killed at sea during the spill.
在海洋石油泄漏事件中，受伤的鸟类经常在水面上死亡，有些最终会被冲上岸边，但有些则会因浸泡在水中而沉没，或者在到达海岸线之前被觅食者吃掉。那些在被冲上岸之前就消失的鸟类很难被统计到，但它们通常代表了总石油泄漏相关死亡率的很大一部分。作为量化深水地平线石油泄漏对海鸟造成的整体影响的过程的一部分，有必要估计在海上丢失的死鸟数量。我们进行了一项研究，以估计在墨西哥湾因石油泄漏而在受海鸟大量使用和影响的地区死亡的海鸟在海上的搁浅概率。我们使用标记-重捕分析从我们的实地研究数据中得出搁浅概率，估计在海上漂浮的死鸟在深海地平线石油泄漏期间搜索的区域中有大约 0.1414 的搁浅概率。对我们模型的敏感性分析和必要假设表明，如果我们的假设被违反，“真实”的搁浅概率可能在 0.11 到 0.16 之间。这些估计值远低于在阿拉斯加水域发生的埃克森瓦尔迪兹石油泄漏事件中估计的海鸟搁浅概率，这可能反映了墨西哥湾温暖水域中更高的分解和觅食率。我们的估计表明，在深海地平线石油泄漏期间被冲上岸边的鸟类尸体仅代表在泄漏期间在海上死亡的鸟类的 14%。
